Author

The Feral Way

Browsing
Solar Power Systems

Solar Power for Campervans : UK Guide

No Comments
Solar Power For Campervans

I’ve installed solar systems on four campervans. The first generated maybe 30% of what the marketing claimed. The second used a controller that wasted 25% of the available power. The third finally works properly, but it took me £340 in wasted components and two complete reinstallations to get there.

Between those three solar installations, I’ve wasted £115 on a panel that was basically a decorative roof ornament, £70 on controllers that threw away power, and countless hours troubleshooting why my “500Wh per day” panel was giving me 150Wh on a good day.

After 30 years as a maintenance manager, you’d think I’d understand electrical systems. And I do – for mains voltage in buildings. But solar on a moving vehicle in the UK climate? That’s different. The marketing is mostly lies, the performance is weather-dependent, and nobody tells you that your £300 solar setup will generate basically nothing for four months of the year.

This guide is everything I wish someone had told me before I bought my first solar panel. Not the California desert performance figures. Not the “perfect world” calculations. The actual reality of solar power in the UK, what genuinely works, and how to avoid the expensive mistakes I made.

This guide covers everything about Solar Power For Campervans that I wish someone had told me before I bought my first solar panel.

Why Solar Isn’t Magic (But It’s Still Worth It)

Let me start with uncomfortable truth: solar panels in the UK will not give you unlimited free power.

What solar marketing says: “200W panel generates 1000Wh per day!”

What actually happens in the UK:

  • Perfect summer day: 500-600Wh (60% of claim)
  • Cloudy summer day: 250-350Wh (30% of claim)
  • Winter day: 80-150Wh (10% of claim)
  • Overcast winter day: 30-60Wh (5% of claim)

But: Solar is still brilliant. Here’s why I have it despite the limitations:

Summer (May-September):

  • My 200W setup generates 50-70Ah daily
  • My usage is 60-70Ah daily
  • Result: Indefinite off-grid capability
  • No need to drive for charging
  • Campsite fees saved: £25/night x 15 nights = £375 per summer

Spring/Autumn (March-April, October-November):

  • Generation: 30-50Ah daily
  • Usage: 60-70Ah daily
  • Result: Extends autonomy from 2 days to 3-4 days
  • Less frequent driving needed

Winter (December-February):

  • Generation: 10-25Ah daily
  • Usage: 70-80Ah daily (heating)
  • Result: Helps but doesn’t solve power needs
  • Still need to drive every 2-3 days

Is solar worth it?

For summer camping: Absolutely. Pays for itself in saved campsite fees.

For year-round: Helps significantly but doesn’t eliminate charging needs in winter.

For weekend warriors: Maybe. Depends on how often you camp April-September.

My Solar Journey (The Expensive Education)

Van #2 (2020): The Disappointing Panel

System:

  • 100W flexible panel: £90
  • Cheap PWM controller: £25
  • Total: £115

Marketing claim: 500Wh per day (4.2Ah @ 12V)

Reality:

  • Best summer day: 180Wh (1.5Ah @ 12V)
  • Average summer day: 120Wh (10Ah)
  • Winter day: 40Wh (3.3Ah)

Why so poor?

  1. Flexible panel was cheap (15% efficiency instead of 18%)
  2. PWM controller wasted power (more on this later)
  3. Panel laid flat (not angled toward sun)
  4. I didn’t understand solar at all

Cost: £115 for system that barely helped. Lesson learned expensively.

Van #3 (2022): The Better Panel, Wrong Controller

System:

  • 200W rigid panel (2x100W): £180
  • “Better” PWM controller: £45
  • Total: £225

Marketing claim: 1000Wh per day

Reality:

  • Best summer day: 450Wh (37Ah)
  • Average summer day: 320Wh (27Ah)
  • Winter day: 100Wh (8Ah)

Much better! But still only 40-50% of marketing claims.

Why?

  1. Better panels (18% efficiency, rigid)
  2. But PWM controller still wasting power
  3. Didn’t understand MPPT vs PWM
  4. Still learned the hard way

After 1 year: Realized PWM was limiting me. Upgraded to MPPT controller (£85). Immediate improvement:

  • Best summer day: 600Wh (50Ah) – 33% increase
  • Average summer day: 450Wh (37Ah) – 40% increase
  • Winter day: 140Wh (12Ah) – 40% increase

Lesson: Controller matters as much as panel quality.

Van #4 (2023-present): Finally Got It Right

System:

  • 200W rigid panels (2x100W Renogy): £180
  • Victron MPPT 75/15 controller: £85
  • Proper installation with cable management
  • Total: £265

Performance (18 months of data):

Summer (June-August):

  • Perfect day: 650Wh (54Ah)
  • Good day: 500Wh (42Ah)
  • Cloudy day: 350Wh (29Ah)
  • Average: 460Wh (38Ah)

Spring/Autumn (March-May, Sept-Nov):

  • Perfect day: 480Wh (40Ah)
  • Good day: 380Wh (32Ah)
  • Cloudy day: 220Wh (18Ah)
  • Average: 340Wh (28Ah)

Winter (December-February):

  • Perfect day: 240Wh (20Ah)
  • Good day: 180Wh (15Ah)
  • Cloudy day: 80Wh (7Ah)
  • Average: 160Wh (13Ah)

This is realistic UK performance. Still only 40-50% of marketing claims, but with proper MPPT controller, it’s actually useful.

Total wasted on learning: £115 (inadequate first system) + £70 (PWM controllers that wasted power) = £185

But knowledge gained: Priceless.

Understanding Solar Basics (The Boring But Essential Bit)

Skip this if you just want to be told what to buy. But understanding helps make better decisions.

How Solar Panels Actually Work

Solar panels convert sunlight to electricity using photovoltaic cells:

  1. Photons (sunlight) hit silicon cells
  2. Electrons get excited and move
  3. This creates DC current
  4. Controller regulates this to charge battery

Important: Panels generate voltage and current. Both matter.

Typical 100W panel specs:

  • Voltage at maximum power (Vmp): 18-20V
  • Current at maximum power (Imp): 5-5.5A
  • Power: 100W (at peak conditions)

But your battery needs:

  • Voltage: 14.4V for charging
  • Current: As much as possible

The controller’s job: Convert 18-20V from panel to 14.4V for battery, while maximizing current.

Peak Sun Hours (Why Marketing Numbers Are Lies)

Panels are rated at “1000W per square meter” of sunlight. This is called “Standard Test Conditions” (STC).

STC conditions:

  • Bright sun, directly overhead
  • 25°C panel temperature
  • No clouds, no atmosphere interference
  • Perfect alignment

Reality in the UK:

  • Sun is never directly overhead (we’re at 51-58°N latitude)
  • Clouds constantly
  • Cool temperatures (good) but low sun angle (bad)
  • Panels flat on roof (not angled)

Peak sun hours in UK:

Summer:

  • South England: 4-5 hours per day
  • Scotland: 3-4 hours per day

Spring/Autumn:

  • South England: 2.5-3.5 hours per day
  • Scotland: 2-3 hours per day

Winter:

  • South England: 1-1.5 hours per day
  • Scotland: 0.5-1 hour per day

Example calculation:

200W panel x 4 peak hours = 800Wh theoretical maximum

But:

  • Panel efficiency losses: -15% = 680Wh
  • Controller losses (PWM): -25% = 510Wh
  • Controller losses (MPPT): -7% = 633Wh
  • Temperature losses: -5% = 600Wh
  • Wiring losses: -3% = 582Wh
  • Flat mounting (not tilted): -15% = 495Wh

Real-world output: 495Wh on perfect UK summer day

This matches my experience exactly.

Temperature Effects

Counterintuitive: Solar panels work BETTER in cold weather.

Panel efficiency by temperature:

  • 25°C (STC): 100% rated output
  • 15°C (UK summer): 105% rated output
  • 5°C (UK winter): 110% rated output
  • 45°C (hot roof in sun): 85% rated output

Why this matters:

Summer: Panel heats to 50-60°C on roof. Loses 15-20% efficiency to heat.

Winter: Panel stays 5-15°C. Gains 5-10% efficiency from cold.

But: Winter has fewer sun hours and lower sun angle, so still generates less overall.

My observation: Coldest clearest winter days (January, Scotland, -2°C) generate amazing power per sun hour. But only 1.5 hours of useful sun, so total still low.

Solar Panel Types: What Actually Matters

I’ve used flexible and rigid panels. Here’s what you need to know.

Monocrystalline vs Polycrystalline

Monocrystalline:

  • Made from single silicon crystal
  • Efficiency: 18-22%
  • Look: Black, uniform color
  • Cost: £90-£150 per 100W
  • What I use

Polycrystalline:

  • Made from multiple silicon crystals
  • Efficiency: 15-17%
  • Look: Blue, mottled appearance
  • Cost: £70-£120 per 100W
  • Older technology

Efficiency matters in vans: You have limited roof space. Higher efficiency = more power per square meter.

My recommendation: Buy monocrystalline. 18%+ efficiency minimum. The extra £20-30 per panel is worth it.

Rigid vs Flexible Panels

Rigid panels:

Pros:

  • Higher efficiency (18-21%)
  • Longer lifespan (20-25 years)
  • Better heat dissipation (air gap under panel)
  • Cheaper per watt
  • More durable
  • Easier to replace if damaged

Cons:

  • Heavier (6-7kg per 100W)
  • Need mounting brackets
  • Higher profile (more visible, wind resistance)
  • Harder to fit curved roofs

Flexible panels:

Pros:

  • Lightweight (2kg per 100W)
  • Stick directly to roof (low profile)
  • Fit curved roofs
  • Stealthier (less obvious)
  • Easier installation

Cons:

  • Lower efficiency (15-17%)
  • Shorter lifespan (5-8 years)
  • Can’t dissipate heat well (stick to hot roof)
  • More expensive per watt
  • Can’t be removed easily
  • Delamination issues common

My experience:

Van #2: Flexible 100W panel (£90)

  • Stuck to roof with 3M tape
  • After 2 years: Output dropped to 60% (delamination suspected)
  • Hot in summer (panel temperature 65°C+)
  • Disappointing performance

Van #3 & #4: Rigid panels (2x100W, £180 total)

  • Mounted on brackets with 10mm air gap
  • After 3 years: Still performing at 95%+ of original
  • Cooler (air circulates underneath)
  • Much better performance

Verdict: Buy rigid panels unless you absolutely need flexible for curved roof. Rigid are better in every way except installation complexity.

Best rigid panels for vans:

Budget (£80-£110 per 100W):

  • Renogy 100W: £95
  • ECO-WORTHY 100W: £85
  • Good performance, decent warranty

Mid-range (£110-£140 per 100W):

  • Victron 100W: £125
  • Better efficiency, longer warranty

Premium (£150-£200 per 100W):

  • SunPower: £180
  • 22% efficiency (highest available)
  • Only worth it if roof space is extremely limited

I use Renogy 100W rigid panels (2x, total £190 in 2022). They’re still going strong, perform well, good value.

Panel Sizing: How Much Do You Need?

Step 1: Calculate daily usage

From my battery guide, my usage:

  • Summer: 65Ah daily
  • Winter: 75Ah daily

Step 2: Decide on solar contribution

Conservative (50% from solar in summer):

  • Need: 32-38Ah from solar
  • Panel: 100W minimum

Balanced (80% from solar in summer):

  • Need: 52-60Ah from solar
  • Panel: 200W minimum

Aggressive (100% from solar year-round):

  • Impossible in UK without massive array
  • Even 400W won’t cover winter usage

My choice: 200W panels. Gives me 100% coverage summer, 40-50% coverage winter.

Space constraints:

100W panel: Typically 1000mm x 670mm (0.67 sq m) 200W panel: Two 100W panels = 1.34 sq m

Check your roof space before buying.

My Transit Custom roof: 2.5m x 1.7m = 4.25 sq m available. 200W of panels uses 31%. Plenty of room.

My recommendation by usage:

Light use (weekend warrior, 30-40Ah daily):

  • 100W panel: £95
  • Adequate for summer, minimal winter help

Regular use (60-70Ah daily):

  • 200W panels: £180-190
  • Good coverage summer, helps significantly in winter
  • This is what I have

Heavy use (80-100Ah daily):

  • 300W panels: £270-300
  • Better winter performance, full summer coverage
  • Requires good roof space

Full-time (100Ah+ daily):

  • 400W+ panels: £360-450
  • Even this won’t cover UK winter completely
  • But maximizes solar contribution

Solar Controllers: PWM vs MPPT (This Cost Me £70)

The controller is as important as the panel. I learned this expensively.

PWM (Pulse Width Modulation)

How it works:

  • Directly connects panel to battery
  • “Pulses” connection on/off rapidly
  • Battery voltage pulls panel voltage down
  • Current limited by battery voltage

Example:

  • Panel produces: 18V at 5.5A = 99W
  • Battery needs: 14.4V
  • PWM connects panel directly
  • Panel pulled down to 14.4V at 5.5A = 79W
  • Lost: 20W (20% of available power)

Pros:

  • Cheap (£20-£45)
  • Simple
  • Reliable (no complex electronics)

Cons:

  • Wastes 20-30% of panel power
  • Inefficient
  • Not worth the saving

My experience (Van #2 & #3):

Van #2: Cheap PWM (£25)

  • 100W panel giving maybe 70W maximum

Van #3: “Better” PWM (£45)

  • 200W panels giving maybe 140-150W maximum

Both wasted huge amounts of power.

Verdict: Don’t buy PWM controllers. The £30-40 saving costs you 25% of your solar power forever. False economy.

MPPT (Maximum Power Point Tracking)

How it works:

  • Monitors panel voltage and current
  • Finds “maximum power point” (optimal voltage for maximum watts)
  • Converts higher voltage to lower voltage with higher current
  • Maintains battery at correct charging voltage
  • Adjusts constantly for changing conditions

Example:

  • Panel produces: 18V at 5.5A = 99W
  • Battery needs: 14.4V
  • MPPT converts 18V to 14.4V
  • Current increases: 99W ÷ 14.4V = 6.9A
  • Controller efficiency: 93-97%
  • Delivered: 92-96W (93-97% of available power)

Pros:

  • 25-40% more power than PWM (especially in winter)
  • Smart (adjusts to conditions)
  • Proper battery charging (multi-stage)
  • Can combine multiple panels
  • Temperature compensation
  • Battery type profiles (AGM, Lithium, etc.)

Cons:

  • More expensive (£60-£150)
  • More complex (more to go wrong)

My experience (Van #4):

Upgraded from PWM to Victron MPPT 75/15 (£85).

Immediate results:

  • Same 200W panels
  • Output increased 30-40% instantly
  • Summer: 37Ah → 50Ah per day
  • Winter: 8Ah → 12Ah per day

18 months later: Still performing brilliantly. Best £85 I spent.

Popular MPPT controllers:

Budget (£60-£90):

  • Renogy Rover 20A: £65
  • EPSolar 20A: £75
  • Basic features, adequate performance

Mid-range (£85-£130):

  • Victron MPPT 75/15: £85 (what I use)
  • Victron MPPT 100/20: £115
  • Renogy Rover Elite 40A: £120
  • Bluetooth monitoring, better features

Premium (£150-£200):

  • Victron MPPT 100/30: £165
  • For 300W+ systems
  • Professional grade

Controller sizing:

Match controller to your panel wattage and system voltage:

For 12V system:

  • 100W panel: 10A controller minimum (I’d buy 15A)
  • 200W panel: 15A controller minimum (I’d buy 20A)
  • 300W panel: 25A controller minimum (I’d buy 30A)
  • 400W panel: 30A+ controller

Voltage rating:

  • 75V controllers: Handle up to 75V input (adequate for 1-3 panels)
  • 100V controllers: Handle up to 100V input (better for multiple panels)

I use Victron MPPT 75/15:

  • Handles my 200W panels (36V maximum in series)
  • 15A output (actually draws 12-13A maximum)
  • Bluetooth app (monitor performance)
  • Perfect for my system

Verdict: Buy MPPT. Victron 75/15 (£85) for 100-200W systems. Worth every penny over PWM.

Installation: How to Actually Mount Panels

This is where it gets practical. Tools out, let’s mount some panels.

Roof Preparation

Step 1: Clean roof thoroughly

  • Wash with soapy water
  • Degrease with isopropyl alcohol
  • Remove any rust or loose paint
  • Let dry completely (24 hours)

Step 2: Plan layout

  • Consider: Roof vents, windows, solar panels, roof bars
  • Leave access to vent for maintenance
  • Consider cable routing
  • Mark positions with tape

Step 3: Check roof structure

  • Where are the ribs/supports?
  • Mount brackets into solid structure
  • Don’t just screw into thin roof skin

Mounting Methods

Method 1: Brackets (What I Use)

Components needed:

  • 4x mounting brackets per panel (£25-35 per set)
  • Sikaflex 512 sealant (£12-18 per tube)
  • Self-tapping screws (M6 or M8)
  • Penny washers (spread load)

Process:

  1. Position brackets:
    • Four corners of panel
    • On roof ribs/supports
    • Mark holes with pencil
  2. Drill pilot holes:
    • 3mm pilot hole
    • Check you haven’t gone through roof lining (I did this once, in van #2, had to patch ceiling)
  3. Apply Sikaflex:
    • Generous amount on bracket base
    • Around screw holes
    • Don’t be shy – this is waterproofing
  4. Fix brackets:
    • Self-tapping screws with penny washers
    • Tight but not overtightened (can crack roof)
    • Sikaflex squeezes out (good – wipe excess)
  5. Let cure:
    • 24 hours minimum before mounting panel
    • 48 hours before driving
  6. Mount panel:
    • Panel sits on brackets with 10mm spacers (air gap)
    • Bolt through panel frame to brackets
    • Use spring washers (vibration resistance)

Pros:

  • Easy to remove/replace panels
  • Air gap keeps panels cool
  • Professional appearance
  • Adjustable (can tilt panels if desired)

Cons:

  • Higher profile (8-10cm above roof)
  • Wind resistance
  • More visible

Cost per panel: £30-45 (brackets + sealant + screws)

Method 2: Adhesive (Flexible Panels Only)

Process:

  1. Clean roof thoroughly (degreased, dry)
  2. Apply Sikaflex or 3M VHB tape to panel back
  3. Position carefully (can’t reposition easily)
  4. Press firmly
  5. Weight panel for 24 hours
  6. Wait 48 hours before use

Pros:

  • Low profile
  • Simple installation
  • Less drilling

Cons:

  • Can’t remove panel without damage
  • Panel heats up (no air gap)
  • Hard to service
  • Permanent

I’ve never used this method (always used rigid panels).

Cable Routing

From panels to controller location (typically near battery).

Route options:

Option 1: Through roof vent

  • Easiest if you have roof vent near panels
  • Run cable through vent hole (add grommet)
  • My method

Option 2: Through new hole

  • Drill hole in roof (20mm)
  • Fit cable gland (waterproof)
  • Apply Sikaflex around gland
  • Professional but more drilling

Option 3: Through existing grommet

  • Many vans have wiring grommets in roof
  • Add solar cable through existing hole
  • Check there’s space

Cable sizing for solar:

Depends on panel wattage and cable length.

For 200W system (17A maximum):

  • 2m run: 4mm² cable
  • 5m run: 6mm² cable
  • 10m run: 10mm² cable

I use 6mm² cable (red and black, solar-rated) for my 8m run from roof to controller. Cost: £28 for 10m.

Critical: Use solar-rated cable. It’s UV resistant (won’t degrade in sun). Normal automotive cable will crack after 2-3 years in sun.

Connecting Panels

Series vs Parallel:

Series (what I use for 2x100W panels):

  • Positive of panel 1 to negative of panel 2
  • Remaining positive and negative to controller
  • Voltage adds: 18V + 18V = 36V
  • Current stays same: 5.5A
  • Power: 36V x 5.5A = 198W
  • Advantages: Lower current = thinner cable, less voltage drop
  • Disadvantages: Shading one panel reduces both

Parallel:

  • All positives together
  • All negatives together
  • To controller
  • Voltage stays same: 18V
  • Current adds: 5.5A + 5.5A = 11A
  • Power: 18V x 11A = 198W
  • Advantages: Shading one panel doesn’t affect other
  • Disadvantages: Higher current = thicker cable needed

My setup: Two 100W panels in series (36V, 5.5A). Works perfectly with Victron 75/15 controller.

Fusing Solar (Essential)

Where fuses go:

  • Between panels and controller (positive wire)
  • As close to panels as practical

My fusing:

  • 20A fuse in waterproof holder on roof
  • Protects cable from panel to controller

Why: If cable shorts (chafed insulation, damage), fuse blows before cable melts.

Controller Installation

Location:

  • Near battery (within 2m)
  • Well-ventilated (gets warm under load)
  • Dry
  • Accessible (for monitoring/settings)

I mounted controller on wall near battery, 1.5m away.

Connections:

Input (from panels):

  • Positive from panels (fused)
  • Negative from panels

Output (to battery):

  • Positive to battery (fused at battery end)
  • Negative to battery

Order of connection (critical):

  1. Connect battery first (positive then negative)
  2. Then connect panels (positive then negative)

Why this order? Controller needs battery voltage to initialize. If you connect panels first, controller can be damaged.

My installation (Van #4):

Time taken: 6 hours (including planning, drilling, sealing, wiring)

Components:

  • 2x Renogy 100W rigid panels: £190
  • Mounting brackets (8 total): £35
  • Victron MPPT 75/15: £85
  • 6mm² solar cable (10m): £28
  • Fuse holder + fuse: £8
  • Sikaflex 512 (2 tubes): £24
  • Screws and fixings: £12
  • MC4 connectors: £15

Total: £397

Results: Flawless installation. No leaks. Perfect performance. 18 months later, still excellent.

Real UK Performance Data (From 18 Months of Monitoring)

Let me show you actual numbers from my system across all seasons.

System: 200W panels + Victron MPPT 75/15 + 105Ah lithium battery

Location: Mix of England (Bristol area) and Scotland (Highlands), with trips to Wales

Summer Performance (June-August)

Best day (July, cloudless):

  • Morning (6am-12pm): 32Ah
  • Afternoon (12pm-6pm): 22Ah
  • Evening (6pm-9pm): 4Ah
  • Total: 58Ah (696Wh)

Battery started at 68%, ended at 100%. Generated more than I used.

Average good day (sunny with some clouds):

  • Total: 42Ah (504Wh)

Covers my 60-65Ah daily usage completely.

Cloudy day:

  • Total: 28Ah (336Wh)

Doesn’t fully cover usage but extends autonomy significantly.

Worst summer day (heavy clouds, drizzle):

  • Total: 14Ah (168Wh)

Better than nothing but not much help.

Summer average over 45 days: 38Ah per day (456Wh)

This matches the 460Wh average I mentioned earlier.

Spring/Autumn Performance (March-May, Sept-Nov)

Best day (April, clear):

  • Total: 38Ah (456Wh)

Average day:

  • Total: 28Ah (336Wh)

Covers about 40-45% of daily usage. Significantly extends autonomy.

Cloudy day:

  • Total: 16Ah (192Wh)

Spring/autumn average over 60 days: 26Ah per day (312Wh)

Winter Performance (Dec-Feb)

Best day (January, Scotland, -2°C, crisp clear):

  • Total: 18Ah (216Wh)

Panels ice cold (good for efficiency) but only 1.5 hours useful sun.

Average winter day:

  • Total: 12Ah (144Wh)

This is maybe 15-20% of daily usage with heating. Helps but doesn’t solve power needs.

Overcast winter day (most days):

  • Total: 6Ah (72Wh)

Basically nothing.

Winter average over 30 days: 11Ah per day (132Wh)

Reality: Winter solar in UK is disappointing. Even 200W barely makes a dent in 75-80Ah daily usage. You’ll still need to drive every 2-3 days.

Factors Affecting Output

What makes big difference:

1. Cloud cover (biggest factor):

  • Thin clouds: -30% output
  • Heavy clouds: -60% output
  • Rain: -75% output

2. Sun angle:

  • Summer noon (50° elevation): 100% potential
  • Winter noon (15° elevation): 40% potential

3. Temperature:

  • Cold panels: +5-10% output
  • Hot panels (60°C): -15% output

4. Dirt/grime:

  • Clean: 100% output
  • Light dust: -5% output
  • Bird droppings: -20% output (local shading)
  • Heavy dirt: -30% output

I clean panels every 2-3 months. Makes noticeable difference.

Real-World Autonomy Impact

Before solar (200Ah AGM, Van #3):

  • Summer: 3 days autonomy
  • Winter: 2 days autonomy

After solar (105Ah lithium + 200W solar, Van #4):

  • Summer: Indefinite (solar covers usage)
  • Winter: 3 days autonomy (solar extends from 2 to 3 days)

Solar added 50% to winter autonomy, made summer essentially unlimited.

Value calculation:

Summer camping: 15 nights average per summer

Without solar: Need campsite every 3 days = 5 nights @ £25 = £125

With solar: Need campsite never (for power) = £0

Annual saving: £125

System cost: £397

Payback: 3.2 years

I’m in year 2. By year 4, it’s paid for itself. Years 5-25 are pure saving.

Installation Mistakes (And How to Avoid Them)

Mistake 1: Cheap Flexible Panel

What I did: Bought £90 flexible panel thinking it was great deal

Reality:

  • 15% efficiency (vs 18% for rigid)
  • Delaminated after 2 years (output dropped to 60%)
  • Stuck to roof (couldn’t remove without damage)
  • Hot (no air circulation)

Cost: £90 wasted + effort to remove

Lesson: Buy rigid panels. Better efficiency, longer life, easier to replace.

Mistake 2: PWM Controller

What I did: Thought £25-45 PWM was adequate

Reality:

  • Wasted 25% of available power
  • 200W panels generating 140-150W

Cost: £70 on two PWM controllers + lost generation

Lesson: Spend £85 on MPPT. 30-40% more power forever.

Mistake 3: Poor Sealing

What I did: Skimped on Sikaflex around brackets

Result: Small leak after 3 months. Water dripping onto ceiling.

Cost: £35 to remove, reseal, repaint ceiling

Lesson: Generous Sikaflex. Waterproofing is critical.

Mistake 4: Drilling Through Roof Lining

What I did: Didn’t check depth. Drilled pilot hole too deep.

Result: Hole in ceiling lining. Had to patch and repaint.

Cost: £25 in materials + embarrassment

Lesson: Know your roof structure. Short pilot holes. Check inside before going deeper.

Mistake 5: Cable Too Thin

What I did: Used 2.5mm² cable for 200W system (10m run)

Result: Voltage drop. Lost 0.8V over 10m. Lost 5-8% power.

Cost: £28 for new 6mm² cable

Lesson: Use proper cable sizing. 6mm² for my 10m run.

Mistake 6: No Fusing

What I did: Didn’t fuse between panels and controller

Why bad: If cable shorts, no protection. Fire risk.

Cost: Lucky – no fire. Added fuse (£8)

Lesson: Always fuse positive wire from panels.

Mistake 7: Wrong Connection Order

What I did: Connected panels to controller before battery

Result: Controller error light. Freaked out. (Controller was actually fine, just confused without battery reference)

Cost: 30 minutes of panic

Lesson: Always connect battery first, then panels.

Monitoring Your Solar System

Knowing what your solar is actually doing matters.

Basic monitoring (free on most MPPT controllers):

  • LED lights showing state (bulk, absorption, float, off)
  • Tells you it’s working but not details

Better monitoring (£0-£20):

  • Voltmeter showing battery voltage
  • Approximate idea of charging
  • Cheap (£8-12 for digital voltmeter)

Professional monitoring (Bluetooth MPPT controllers):

  • Real-time data (voltage, current, power, energy)
  • Historical data (daily/weekly/monthly generation)
  • Settings adjustable via app
  • This is what I have

My setup:

Victron MPPT 75/15 with Bluetooth (£85 total, Bluetooth built-in).

VictronConnect app on phone shows:

  • Current generation: 48W
  • Panel voltage: 35V
  • Battery voltage: 14.4V
  • Today’s generation: 38Ah
  • Yesterday: 42Ah
  • Last week: 285Ah

Brilliant. Know exactly what solar is doing.

What I check:

  • Morning: Check yesterday’s generation
  • Mid-day: Check current generation (making sure it’s working)
  • Evening: Check total for day

Takes 30 seconds. Helps identify issues (dirty panels, shading, controller problems).

Worth paying extra for Bluetooth MPPT? Absolutely. The data is invaluable.

Maintenance (Surprisingly Important)

Solar panels need maintenance. Not much, but ignoring it costs power.

Every 2-3 months:

1. Clean panels:

  • Hose with water
  • Soft brush for stubborn dirt
  • Don’t use harsh chemicals
  • Don’t use abrasive materials

Bird droppings are worst – they shade cells significantly. Clean immediately.

Cleaning impact:

  • Dirty panels: 78% output
  • Clean panels: 100% output

That’s 22% power loss from dirt. Worth the 10 minutes to clean.

2. Check connections:

  • Terminals tight
  • No corrosion
  • Cables not chafed
  • Sealant still intact around roof penetrations

3. Check output:

  • Compare to previous months
  • Significant drop (20%+) might indicate panel damage or controller issue

Annually:

1. Reseal roof penetrations:

  • Check Sikaflex around brackets
  • Add more if needed
  • Better to over-seal than under-seal

2. Check panel mounting:

  • Bolts tight (vibration can loosen)
  • Brackets secure
  • No cracks in roof around mounts

3. Check cable:

  • UV damage (cable going brittle)
  • Insulation intact
  • Replace if showing wear

My maintenance routine:

Quick clean every 2 months: 15 minutes

Annual inspection: 1 hour

Problems I’ve found through maintenance:

  • Bird droppings (common – clean weekly in some locations)
  • Loose MC4 connector (panel to cable connection – tightened, problem solved)
  • Sikaflex crack around one bracket (resealed, no leak developed)

None of these would have been obvious without checking. All would have caused issues eventually.

Combining Solar with Other Charging

Solar is brilliant but it’s not the only charging source. My complete charging setup:

1. Solar (200W + MPPT): £265

  • Summer: 100% of needs
  • Winter: 15-20% of needs

2. Alternator charging (DC-DC 18A): £157

  • Provides: 18Ah per hour driving
  • Use: Primarily in winter

3. Mains hook-up (CTEK charger): £72

  • Use: Occasionally on campsites

Total charging infrastructure: £494

How they work together:

Summer typical day:

  • Solar generates: 42Ah
  • Usage: 65Ah
  • Shortfall: 23Ah
  • Drive 1.5 hours every 4-5 days to top up

Actually, solar usually covers everything April-September. Rarely need alternator.

Winter typical day:

  • Solar generates: 12Ah
  • Usage: 75Ah
  • Shortfall: 63Ah
  • Drive 3.5 hours (63Ah ÷ 18A) or 2 hours on day 1, 2 hours on day 3

Winter needs alternator charging regularly.

System redundancy:

If solar fails: Alternator covers everything (just drive more)

If alternator fails: Solar covers summer, need campsites in winter

If both fail: Mains hook-up on campsites

Having multiple charging sources means no single point of failure.

Complete Solar System Costs

Budget System (100W + PWM) – £145-£180

For: Weekend warriors, light usage, tight budget

Components:

  • 100W rigid panel: £95
  • PWM controller: £35
  • Mounting brackets: £30
  • Cable (6mm², 5m): £15
  • Fuse holder + fuse: £8
  • Fixings and sealant: £20

Total: £203

Performance:

  • Summer: 20-25Ah per day
  • Winter: 6-10Ah per day

Verdict: Helps in summer. Barely useful in winter. PWM wastes power but keeps cost down.

Standard System (200W + MPPT) – £330-£400

For: Regular users, year-round camping, best value

Components:

  • 2x 100W rigid panels: £190
  • Victron MPPT 75/15: £85
  • Mounting brackets (8): £35
  • Cable (6mm², 10m): £28
  • Fuse holder + fuse: £10
  • MC4 connectors: £15
  • Fixings and sealant: £35

Total: £398

This is what I have.

Performance:

  • Summer: 38-50Ah per day (covers usage)
  • Winter: 12-18Ah per day (extends autonomy)

Verdict: Sweet spot. Adequate power for real use. Pays for itself in 3-4 years.

Large System (400W + MPPT) – £620-£720

For: Heavy users, full-time living, maximum solar

Components:

  • 4x 100W rigid panels: £380
  • Victron MPPT 100/30: £165
  • Mounting brackets (16): £70
  • Cable (10mm², 10m): £60
  • Fuse holder + fuse: £12
  • MC4 connectors: £18
  • Fixings and sealant: £60

Total: £765

Performance:

  • Summer: 80-100Ah per day (excess power)
  • Winter: 25-35Ah per day (helps significantly)

Verdict: Best solar possible for UK van. Still won’t cover winter usage completely, but maximizes solar contribution.

Three Realistic Scenarios

Scenario 1: Sarah – Weekend Camper (30 nights/year)

Usage: 40Ah daily (lights, phone charging, occasional laptop)

Solar: 100W panel + PWM controller = £145

Performance:

  • Summer weekends: Solar generates 20Ah, she uses 40Ah = needs to drive or use campsite every 2-3 days
  • Acceptable for occasional use

Verdict: Basic solar helps but not essential. Could skip solar and just use alternator charging.

Scenario 2: Me – Regular User (80-100 nights/year)

Usage: 65Ah daily (lights, fridge, laptop, water pump)

Solar: 200W panels + MPPT = £398

Performance:

  • Summer: Solar generates 38-50Ah, covers 60-80% of usage = nearly indefinite autonomy
  • Winter: Solar generates 12Ah, covers 15-20% = extends autonomy from 2 days to 3 days

Verdict: Essential. Transforms summer camping. Helps significantly in winter. Paid for itself in 3 years.

Scenario 3: Tom & Lisa – Full-Time (300+ nights/year)

Usage: 85Ah daily (lights, fridge, laptop, phone, water pump, occasional inverter)

Solar: 400W panels + MPPT = £765

Performance:

  • Summer: Solar generates 80-100Ah, covers 95-115% = indefinite autonomy, slight excess
  • Winter: Solar generates 25-35Ah, covers 30-40% = extends autonomy from 2.5 days to 4 days

Verdict: Necessary. Maximum practical solar for UK. Still need alternator charging in winter but solar contribution is significant.

Common Questions (From Experience)

Q: Can I install solar myself?

Yes. I did. If you can use a drill and crimper, you can install solar. Takes 4-6 hours.

Q: Will solar keep my battery charged if I don’t use the van for weeks?

Summer: Yes, easily. My van sits for 2-3 weeks sometimes. Battery stays 100%.

Winter: Depends. If you have parasitic draws (alarms, trackers), maybe not. My battery drops 5% per week in winter with solar.

Q: Do I need planning permission for panels on my van?

No. It’s a vehicle modification, not a building.

Q: Can I run 240V appliances from solar?

Only with an inverter, and inefficiently.

Example: 600W inverter from solar

  • Panel generates: 200W
  • Battery: 105Ah @ 12V = 1260Wh stored
  • Inverter draws: 50A @ 12V for 600W output
  • Runtime: 1260Wh ÷ 600W = 2.1 hours maximum

Solar generates slower than inverter consumes. You’ll drain battery.

Better: Use 12V appliances. Much more efficient.

Q: What happens in winter when panels are covered in snow?

They don’t generate. Snow must be cleared. I brush snow off panels (it’s usually not that stuck).

Q: Can I tilt panels to catch more sun?

Yes, but complicated. Requires hinged mounting. I keep mine flat (simpler, lower profile). Loss is maybe 15-20% efficiency but worth it for simplicity.

Q: Will partial shading ruin output?

Yes. Shading even 10% of one panel can reduce output 40-60% (cells are in series).

Panel placement: Avoid areas that get shaded by roof vent, satellite dish, roof bars.

Q: How long will panels last?

Rigid panels: 20-25 years (gradual degradation to 80% of original)

Flexible panels: 5-8 years (often fail sooner from delamination)

I’m 3 years into rigid panels. Still 95%+ of original output.

My Final Recommendations

After three solar installations, £185 in wasted components, and 18 months of detailed monitoring:

For most people (regular campers, 50-100 nights/year):

Buy 200W rigid panels (2x100W) + Victron MPPT 75/15.

Components:

  • 2x Renogy 100W rigid panels: £190
  • Victron MPPT 75/15 (Bluetooth): £85
  • Mounting brackets: £35
  • 6mm² cable: £28
  • Fuse holder: £10
  • MC4 connectors: £15
  • Fixings/sealant: £35

Total: £398

This gives you:

  • Summer: Near-indefinite autonomy
  • Winter: Extends autonomy 50%
  • Payback: 3-4 years
  • Lifespan: 20+ years

This is exactly what I have. Zero regrets.

For light users (weekends only, 20-40 nights/year):

Consider skipping solar entirely. Use alternator charging + occasional campsite.

Or buy 100W panel + basic MPPT (£180 total) for summer help.

For heavy users (full-time, 200+ nights/year):

Buy 300-400W panels + Victron MPPT 100/30.

Maximum practical solar for UK van. Won’t cover winter completely but maximizes contribution.

Total: £620-£765

Final Thoughts

Solar in the UK isn’t perfect. You won’t get the performance marketing promises. Winter output is disappointing. You’ll still need other charging methods.

But summer solar is brilliant. May-September, my 200W system covers 100% of my power needs. I can wild camp indefinitely. No campsites. No driving for charging. Just free solar power.

That’s worth £398 to me. Paid for itself in saved campsite fees in 3 years. Years 4-25 are pure saving.

If I built van #5 tomorrow, I’d buy exactly the same system. 200W rigid panels. Victron MPPT. Proper mounting. That’s the sweet spot for UK vanlife.

Now stop reading, buy some solar panels, and enjoy free power for the next 20 years. Just don’t expect miracles in December.

Continue Reading
By
Alternator & Split Charging

Split Charging And Alternator Wiring Guide

No Comments
Split Charging & Alternator Wiring Guide

After three decades working with building electrical systems, you’d think I’d breeze through 12V van wiring. Wrong. Vehicle electrical systems have their own peculiarities, and I’ve learned them all the expensive and occasionally dangerous way.

Welcome to the Split Charging And Alternator Wiring Guide. This guide is everything I wish someone had told me before I connected my first leisure battery to my alternator.

This guide is everything I wish someone had told me before I connected my first leisure battery to my alternator. Not the sanitized version. Not the perfect installations. The actual reality of split charging, what genuinely works, what’s dangerous rubbish, and how to avoid setting fire to your van.

Why Split Charging Actually Matters

Your van has two electrical systems that need to stay separate but also work together:

Starter battery system:

  • Powers starter motor (200-400A draw)
  • Powers vehicle electronics (lights, ECU, dashboard)
  • Must always have enough charge to start engine
  • Typically 60-100Ah capacity
  • If this dies, you’re stranded

Leisure battery system:

  • Powers your conversion (lights, fridge, pump, heater)
  • Can be discharged heavily without issues
  • Typically 100-200Ah capacity
  • If this dies, you’re uncomfortable but not stranded

The problem: Both batteries need charging from the alternator, but:

  • Leisure battery shouldn’t drain starter battery
  • Starter battery shouldn’t drain leisure battery
  • Both need charging when engine runs
  • Neither should interfere with vehicle electronics
  • System must be safe and legal

Get this wrong and you’re either stranded with a flat starter battery or melting cables or damaging your alternator (happened once, £280 to replace).

Understanding Your Alternator (Critical Background)

Before you wire anything, understand what you’re working with.

What Your Alternator Actually Does

Your alternator converts mechanical energy (from the engine) into electrical energy to:

  1. Charge the starter battery
  2. Power vehicle electrical systems
  3. (Potentially) charge your leisure battery

Typical van alternator specs:

  • VW Transporter T5/T6: 140-180A
  • Ford Transit Custom: 150-180A
  • Mercedes Sprinter: 180-220A
  • Older vans (pre-2010): 90-120A

But: That’s maximum output. Typical driving output: 60-80A total.

That’s split between:

  • Vehicle systems: 15-30A (lights, ECU, dashboard, fans, etc.)
  • Starter battery maintenance: 5-15A (once started, just maintaining)
  • Available for leisure: 30-60A

Important: Modern vans with lots of electronics (heated seats, parking sensors, cameras, climate control) use more power. Less available for leisure charging.

Alternator Output Voltage

This is critical and often misunderstood.

Typical alternator output: 13.8-14.4V (varies with RPM, temperature, load)

What batteries actually need:

AGM batteries:

  • Bulk charge: 14.4-14.7V
  • Absorption: 14.4V
  • Float: 13.8V

Lithium batteries:

  • Bulk charge: 14.4-14.6V
  • Absorption: 14.6V
  • No float needed

The problem: Many alternators regulate to 14.2V maximum. This is fine for starter batteries but inadequate for proper AGM charging and borderline for lithium.

My Transit Custom alternator: 14.3V at idle, 14.2V at cruise. Just barely adequate.

Solution: DC-DC charger boosts voltage to correct level regardless of alternator output.

Can Your Alternator Handle Leisure Charging?

Rule of thumb: If your alternator is 120A or more, you can safely draw 30A for leisure charging.

Check your alternator rating:

  • Look on the alternator body (stamped rating)
  • Check vehicle manual
  • Google “your van model + alternator amperage”

My vans:

  • 2008 T5: 140A alternator (fine for 30A leisure)
  • 2015 Transit Custom: 150A alternator (fine for 30A leisure)
  • 2017 Transit Custom: 150A alternator (fine for 30A leisure)

Warning signs your alternator is struggling:

  • Dimming lights when leisure battery charging starts
  • Battery warning light flickers
  • Alternator getting very hot (can smell it)
  • Alternator making noise (whining or grinding)
  • Vehicle electronics glitching

I killed an alternator in van #2: Used a 30A DC-DC charger on a van with a weak 90A alternator (2006 Vivaro). Alternator lasted 8 months then failed. Cost: £280 replacement.

Lesson: Check alternator capacity before sizing your charging system.

Smart Alternators (2015+ Vans)

Modern vans (2015 onwards typically) have “smart alternators” designed for fuel efficiency.

How they work:

  • Only charge battery when needed (not constantly)
  • Reduce output when cruising (better MPG)
  • Increase output when braking (regenerative)
  • Regulate voltage based on battery condition

The problem for split charging:

  • Output voltage varies (13.5-14.8V)
  • May not charge leisure battery consistently
  • Simple split charge relays don’t work well
  • Can confuse basic DC-DC chargers

My experience: 2017 Transit Custom has smart alternator. Basic split charge relay was useless (only activated occasionally). Upgraded to DC-DC charger with smart alternator detection (Victron Orion) – works perfectly.

Solution: Use a DC-DC charger with smart alternator compatibility (most modern DC-DC chargers handle this).

Split Charging Methods: The Honest Comparison

I’ve used three main methods across four vans. Here’s what actually happens.

Method 1: Split Charge Relay (Voltage Sensing)

What it is: An automatic relay that connects batteries when it detects alternator voltage (13.5V+) and disconnects when voltage drops (engine off).

Cost: £25-£60

How it works:

  1. Engine starts → voltage rises to 13.8V+
  2. Relay detects voltage, closes contacts
  3. Starter and leisure batteries connected
  4. Both charge from alternator
  5. Engine stops → voltage drops to 12.5V
  6. Relay opens, batteries isolated

Suitable for:

  • Older vans (pre-2015, non-smart alternators)
  • AGM batteries only (not lithium)
  • Budget builds (£500-£1000 total electrical)
  • Light usage (30-50 nights/year)

Popular models:

  • Ring RSCDC30 (30A, £28)
  • Durite 0-727-33 (140A, £35)
  • Voltage Sensitive Relay (VSR) generic (£25-£40)

Pros:

  • Cheap (£25-60)
  • Simple to install
  • No programming needed
  • Works with any battery type (if voltage is correct)
  • Reliable (no electronics to fail)

Cons:

  • No control over charging voltage (uses whatever alternator provides)
  • Can overcharge or undercharge depending on alternator
  • Doesn’t work well with smart alternators
  • Both batteries connected = both can drain if relay fails
  • Slow charging (limited by alternator voltage)
  • Can’t charge lithium properly (wrong voltage profile)

Cable sizing for split charge relay:

For 30A relay with 3m cable run:

  • Minimum: 6mm²
  • Recommended: 10mm²
  • Safe: 16mm²

Installation complexity: Simple. Four connections:

  1. Positive from starter battery to relay
  2. Positive from relay to leisure battery
  3. Negative to chassis (earth)
  4. Sense wire to ignition (optional on some models)

Verdict: Adequate for budget builds with AGM batteries and older vans. Not suitable for modern vans or lithium batteries. I wouldn’t use one again now DC-DC chargers are affordable.

Method 2: Battery Isolator (Diode-Based)

What it is: Uses diodes to allow current flow in one direction (alternator to batteries) but prevent reverse flow (batteries draining each other).

Cost: £45-£95

How it works:

  • Diodes allow charging current from alternator to both batteries
  • Prevent batteries from discharging into each other
  • No relay, no voltage sensing, always connected

Pros:

  • Simple (no moving parts)
  • Automatic (no sensing required)
  • Cheap-ish (£45-95)

Cons:

  • Voltage drop across diodes (0.6-0.8V lost)
  • Both batteries charge at same voltage (not ideal if different types)
  • Gets hot under load (needs cooling)
  • Inefficient (wastes power as heat)
  • Outdated technology

My experience: Never used one. Tested a mate’s setup (Sterling Battery-to-Battery isolator, £75).

What I observed:

  • Warm to touch when charging
  • Voltage at leisure battery: 13.6V (alternator was 14.3V – 0.7V drop)
  • This is inadequate for AGM (needs 14.4V minimum)
  • Basically useless for proper charging

Verdict: Don’t buy these. Worse than split charge relays in every way. Outdated technology that wastes voltage.

Method 3: DC-DC Battery Charger (The Right Way)

What it is: Intelligent power supply that takes alternator voltage (12-14.4V) and converts it to optimal charging voltage (14.2-14.6V) for your specific battery type.

Cost: £100-£220

How it works:

  1. Monitors both starter and leisure batteries
  2. Only activates when starter battery is charged (13.5V+)
  3. Draws power from alternator
  4. Converts (boosts/bucks) to correct voltage for leisure battery
  5. Charges in proper 3-stage profile:
    • Bulk: Maximum current until 80% full
    • Absorption: Reduced current, maintains voltage
    • Float: Maintains full charge (AGM only, not lithium)
  6. Protects both batteries from damage

Suitable for:

  • Modern vans (2010+, especially 2015+ with smart alternators)
  • Any battery type (selectable profiles: AGM, Gel, Lithium)
  • Regular use (50+ nights/year)
  • Proper battery charging
  • Anyone who wants reliability

Popular models:

Budget (£100-£140):

  • Renogy 20A DC-DC (£105)
  • CTEK D250SE (£125)
  • Sterling BB1230 (£135)

Mid-range (£150-£180):

  • Victron Orion 12/12-18 (£157) – what I use
  • Renogy 40A DC-DC (£165)
  • CTEK D250SA + Smartpass (£180)

Premium (£190-£220):

  • Victron Orion 12/12-30 (£210)
  • Sterling BB1260 (£215)

Amperage guide:

  • 18A charger: Fine for 100-150Ah batteries
  • 30A charger: Better for 150-200Ah batteries
  • 40A charger: Overkill unless you have 200Ah+ and short driving times

Pros:

  • Proper charging voltage (extends battery life)
  • Works with smart alternators
  • Selectable battery profiles (AGM, Gel, Lithium)
  • Fast charging (full current even at idle)
  • Protects both batteries
  • Three-stage charging (bulk, absorption, float)
  • Can combine with solar (most models)
  • Smart (monitors battery condition)

Cons:

  • More expensive (£100-220)
  • Slightly more complex installation (more wires)
  • Needs programming for battery type
  • Can fail (electronics vs simple relay)

My experience (Van #3 & #4):

Van #3: Generic 30A DC-DC charger (£145, can’t remember brand).

Worked well for 2 years with 200Ah AGM. Charged properly.

Van #4: Victron Orion 12/12-18 (£157).

18 months of use, zero issues:

  • Charges 105Ah lithium from 20% to 95% in 2.5 hours driving
  • Works perfectly with smart alternator
  • Bluetooth monitoring (shows voltage, current, temperature)
  • Set to lithium profile (14.6V absorption)
  • Never gets above warm (hand temperature)
  • Absolutely bulletproof

Best feature: Bluetooth app shows exactly what’s happening (charging current, voltage, power, temperature, state). Can see charging working in real-time.

Cable sizing for DC-DC chargers:

For 18A charger (my setup):

  • Input side (starter to DC-DC): 4mm² minimum, I use 6mm²
  • Output side (DC-DC to leisure): 4mm² minimum, I use 6mm²
  • Cable runs: 2m from starter, 1.5m to leisure

For 30A charger:

  • Input: 6mm² minimum, recommend 10mm²
  • Output: 6mm² minimum, recommend 10mm²

Installation complexity: Moderate. More connections than split charge relay:

  1. Positive from starter battery (fused)
  2. Negative from starter battery
  3. Positive to leisure battery (fused)
  4. Negative to leisure battery
  5. Ignition sense wire (optional on some models)
  6. Temperature sensor (optional)

Takes 2-3 hours to install properly.

Verdict: This is what everyone should use now. £157 (Victron Orion 18A) is the sweet spot. Works with any battery type. Works with modern alternators. Charges properly. Lasts forever. I’d buy the same one again tomorrow without hesitation.

Complete Wiring Guide: The Safe Way

Right. Time for the detailed bit. This is where I explain exactly how to wire it so you don’t melt cables or drain batteries.

Tools You’ll Need

Essential:

  • Multimeter (£15-45)
  • Wire strippers (£15-25)
  • Ratchet crimpers (£25-40)
  • Cable cutters (£12-18)
  • Socket set (£25-60)
  • Spanners (£15-30)

Useful:

  • Heat gun (£20-40)
  • Soldering iron (optional, £25-40)
  • Label maker (£25)
  • Electrical tape (£5)

Safety:

  • Insulated gloves (£8)
  • Safety glasses (£6)
  • Fire extinguisher (£25)

Total: £171-£337 (if buying everything new)

Components You’ll Need

For a typical DC-DC charger installation (18A):

Main components:

  • DC-DC charger (£100-180)
  • Cable: 6mm² red (5m, £15)
  • Cable: 6mm² black (5m, £15)
  • Fuse holders: 2x MIDI or ANL (£8-£18)
  • Fuses: 30A (2x, £5-£10)
  • Battery terminals: 4x M8 ring (£8)
  • Heat shrink: assorted (£6)
  • Cable ties: pack of 100 (£5)
  • Cable protector: 3m split loom (£8)

Optional but recommended:

  • In-line switch for DC-DC (£12)
  • Voltmeter near leisure battery (£8)
  • Temperature sensor for DC-DC (£15)

Total materials (excluding charger): £85-£130

Grand total: £185-£310 (including 18A DC-DC charger)

Step-by-Step Installation (DC-DC Charger)

I’m going to walk through installing a Victron Orion 12/12-18 because that’s what I know intimately. Other DC-DC chargers are similar.

Location: DC-DC charger should be:

  • Close to leisure battery (within 2m)
  • Well-ventilated (gets warm under load)
  • Accessible (you might need to adjust settings)
  • Dry (not where water can drip on it)
  • Away from extreme heat (not right next to heater)

I mounted mine on the wall behind the driver’s seat, 1.5m from leisure battery. Perfect location.

Step 1: Disconnect batteries (CRITICAL)

Safety first. Always.

  1. Turn off all systems
  2. Remove keys from ignition
  3. Disconnect NEGATIVE terminal from starter battery
  4. Disconnect NEGATIVE terminal from leisure battery (if already installed)
  5. Wait 5 minutes (capacitors discharge)

Step 2: Plan cable routes

From starter battery to DC-DC charger location:

  • Through bulkhead (rubber grommet required)
  • Along chassis rail
  • Away from hot components (exhaust, turbo)
  • Away from moving parts (steering, suspension)
  • Secured every 30cm

My route: Along passenger side chassis rail, through existing bulkhead grommet (£8 grommet from Screwfix), into cargo area behind driver’s seat. Total run: 2.5m.

Step 3: Install cable from starter battery to DC-DC

Positive cable (red, 6mm²):

  1. At starter battery end:
    • Cut cable to length plus 20cm (you’ll trim later)
    • Strip 15mm insulation
    • Crimp M8 ring terminal
    • Heat shrink over crimp
  2. Route cable:
    • Through bulkhead grommet
    • Along chassis rail
    • Secure with cable ties every 30cm
    • Use split loom protector where it might chafe
  3. FUSE at starter battery end:
    • CRITICAL: Fuse must be within 30cm of battery positive
    • I use MIDI fuse holder with 30A fuse
    • If fuse is further away, you risk cable fire in a short circuit
  4. At DC-DC end:
    • Strip 10mm
    • Crimp appropriate terminal for DC-DC input
    • Leave slightly long (easier to trim than add)

Negative cable (black, 6mm²):

  1. At starter battery end:
    • Crimp M8 ring terminal
    • Connect to chassis near battery (clean metal, good earth point)
    • NOT directly to battery negative (vehicle electronics use this)
  2. Route cable:
    • Same route as positive (zip-tied together)
  3. At DC-DC end:
    • Strip 10mm
    • Connect to DC-DC input negative

Step 4: Install cable from DC-DC to leisure battery

Much shorter run (1-2m typically).

Positive cable (red, 6mm²):

  1. At DC-DC end:
    • Strip 10mm
    • Connect to DC-DC output positive
  2. Route cable:
    • To leisure battery location
    • Keep away from sharp edges
  3. FUSE at leisure battery end:
    • MIDI fuse holder with 25A fuse
    • Within 30cm of battery
  4. At leisure battery end:
    • Crimp M8 ring terminal
    • Ready to connect (but don’t yet)

Negative cable (black, 6mm²):

  1. At DC-DC end:
    • Strip 10mm
    • Connect to DC-DC output negative
  2. At leisure battery end:
    • Crimp M8 ring terminal
    • Ready to connect

Step 5: Mount the DC-DC charger

I used two small L-brackets (£3) and M5 bolts.

Mounted to wall panel with:

  • Rubber washers (vibration dampening)
  • Lock washers (won’t loosen)
  • Adequate clearance around unit (10cm minimum)

Step 6: Optional connections

Ignition sense wire:

Some DC-DC chargers have this. Tells charger when engine is running.

Mine doesn’t need it (Victron Orion senses voltage rise from alternator starting). But if yours does:

  • Small wire (1mm² is fine)
  • Connect to ignition-live circuit (fused at 5A)
  • I used the cigarette lighter circuit (check with multimeter)

Temperature sensor:

Optional but useful. Monitors battery temperature, adjusts charging.

I didn’t install one (can’t be bothered, honestly). Battery stays in comfortable temperature range.

Step 7: Double-check everything

Before connecting batteries:

  • [ ] All terminals crimped properly (pull test – should not come off)
  • [ ] Heat shrink over all terminals
  • [ ] Fuses at both battery ends (within 30cm)
  • [ ] Cables secured (no loose hanging)
  • [ ] No chafing points
  • [ ] Correct polarity everywhere (red = positive, black = negative)
  • [ ] DC-DC charger mounted securely
  • [ ] All connections tight
  • [ ] Split loom over exposed cable
  • [ ] Cable routes sensible (away from heat/movement)

Step 8: Connect batteries (in order)

  1. Connect leisure battery NEGATIVE
  2. Connect leisure battery POSITIVE (watch for spark – normal)
  3. Connect starter battery NEGATIVE
  4. Connect starter battery POSITIVE

Why this order? If you accidentally touch spanner to chassis while working, you won’t short circuit (negative already connected).

Step 9: Test before driving

  1. Check voltages with multimeter:
    • Starter battery: Should be 12.5-12.8V
    • Leisure battery: Should be 12.5-13.2V (depending on state)
  2. Turn on ignition (don’t start engine):
    • Check DC-DC charger powers on (LED should light)
    • Some models won’t activate until engine starts
  3. Start engine:
    • DC-DC should activate (LED changes, or hear click)
    • Check voltage at leisure battery: Should rise to 14.4-14.6V within 30 seconds
    • Check current: Multimeter on output cable should show charging current
  4. Check for heat:
    • After 5 minutes, cables should be cool to warm (not hot)
    • DC-DC charger should be warm (hand temperature, not too hot to touch)
    • Fuse holders should be cool
  5. Check connections:
    • No loose wires
    • No arcing or sparking
    • No smell of burning

Step 10: First proper test drive

  1. Drive for 30 minutes
  2. Stop, check everything:
    • Cables (should be warm, not hot)
    • Terminals (tight, no looseness)
    • DC-DC charger (warm, not hot)
    • Voltage (leisure should be charging)
  3. If all good: drive another hour
  4. Recheck everything
  5. If still good: you’re done

My installation (Van #4):

Total time: 4 hours (including planning and testing)

Cables used:

  • Starter to DC-DC: 2.5m of 6mm²
  • DC-DC to leisure: 1.5m of 6mm²
  • Total: 4m cable (bought 5m, had spare)

No issues. Works perfectly. 18 months later, still perfect.

Split Charge Relay Installation (For Comparison)

Simpler but less good. If you’re using a VSR instead of DC-DC:

Main connections:

  1. Positive from starter battery → Fuse (30A) → Relay input
  2. Positive from relay output → Fuse (25A) → Leisure battery
  3. Negative from relay → Chassis earth
  4. (Optional) Sense wire to ignition

Basically the same as DC-DC but with only one device instead of input/output sides.

Easier to install but worse performance.

Cable Sizing: The Critical Math

This is where I cocked up twice. Let me explain properly so you don’t.

Why Cable Size Matters

Cable size affects three things:

  1. Voltage drop (thinner = more drop = less charging)
  2. Heat generation (thinner = more heat = fire risk)
  3. Power loss (thinner = more resistance = wasted power)

The melted cable incident (Van #3):

I used 6mm² cable for a 30A DC-DC charger. Manufacturer said “6mm² rated for 50A.” Should be fine, right?

Wrong.

That 50A rating assumes:

  • Short run (1m)
  • Cool environment (20°C)
  • Single cable (not bundled)
  • Perfect ventilation

My reality:

  • 3m run (longer)
  • Engine bay temperatures (40-60°C)
  • Cable bundled with others (shared heat)
  • Against metal occasionally (conducted heat away… into metal)

Actual safe current: More like 30-35A continuous in those conditions.

At 35A continuously for 2 hours, cable got hot enough to melt insulation in one section.

Proper Cable Sizing Method

Use a cable sizing calculator or table. Don’t guess.

Factors to consider:

  1. Current (A)
  2. Cable length (m)
  3. Acceptable voltage drop (typically 3% max for 12V = 0.36V)
  4. Temperature environment
  5. Installation method (bundled or singles)

Simple table (12V system, 3% voltage drop, 3m run):

CurrentCable Size (minimum)Recommended
10A1.5mm²2.5mm²
20A2.5mm²4mm²
30A4mm²6mm²
40A6mm²10mm²
60A10mm²16mm²
80A16mm²25mm²
100A16mm²25mm²

For longer runs, go thicker.

Online calculators I use:

  • 12VoltPlanet cable calculator (UK-specific)
  • Victron cable calculator (very detailed)

Real-World Cable Choices

For 18A DC-DC charger (what I have):

Input side (starter to DC-DC):

  • Minimum: 4mm²
  • Recommended: 6mm² (what I use)
  • Overkill: 10mm²

My run: 2.5m, I use 6mm². Cool under load.

Output side (DC-DC to leisure):

  • Minimum: 4mm²
  • Recommended: 6mm² (what I use)
  • Overkill: 10mm²

My run: 1.5m, I use 6mm². Cool under load.

For 30A DC-DC charger:

Input side:

  • Minimum: 6mm²
  • Recommended: 10mm²
  • Safe: 16mm²

Output side:

  • Minimum: 6mm²
  • Recommended: 10mm²
  • Safe: 16mm²

For 40A+ systems:

Use 16mm² or 25mm². Don’t mess around. Heavy gauge is safer.

Cable cost (UK, 12V automotive cable):

  • 6mm² red/black: £3-£4 per metre
  • 10mm² red/black: £5-£7 per metre
  • 16mm² red/black: £8-£11 per metre
  • 25mm² red/black: £13-£18 per metre

My advice: Budget an extra £20-£30 and go one size thicker than minimum. Peace of mind is worth it.

Fusing: The Essential Safety Component

Fuses save your van from burning down. Take this seriously.

Why Fusing Matters

If a cable shorts to chassis (chafed insulation, crushed cable, accident damage), current can be hundreds of amps. Cable heats up instantly. Fire starts within seconds.

A properly sized fuse blows before the cable reaches dangerous temperature.

Where fuses go:

  1. Positive terminal of starter battery (within 30cm)
  2. Positive terminal of leisure battery (within 30cm)

Why within 30cm? If the short happens between battery and fuse, the fuse can’t protect that section. Keep it short.

Fuse Sizing

Fuse size should be:

  • Smaller than cable rating (protects cable)
  • Larger than maximum load (doesn’t blow unnecessarily)

Example: 18A DC-DC charger on 6mm² cable

  • Cable rated: 50A (in perfect conditions)
  • Derating for reality: 35-40A safe continuous
  • Maximum load: 20A (DC-DC plus 10% margin)
  • Fuse size: 30A (protects cable, handles load)

My fusing:

  • Starter battery end: 30A MIDI fuse
  • Leisure battery end: 25A MIDI fuse

Fuse types:

Blade fuses (automotive):

  • Max size: 30A
  • Not suitable for main charging circuits
  • Use for small accessories only

MIDI fuses:

  • 30A-100A range
  • Good for charging circuits
  • What I use (£8-12 for holder + fuse)

ANL fuses:

  • 40A-300A range
  • Better for high current
  • More expensive (£12-20 for holder + fuse)

MEGA fuses:

  • 80A-500A range
  • Professional grade
  • Expensive (£20-35 for holder + fuse)

My recommendation:

  • Charging circuits: MIDI fuses (30-50A range)
  • Main battery feeds: ANL fuses (80-150A range)

My Fusing Setup (Van #4)

Starter battery positive terminal:

  • 30A MIDI fuse in holder (£10)
  • 15cm cable to fuse
  • Then run to DC-DC

Leisure battery positive terminal:

  • 100A ANL fuse (main) for all systems (£18)
  • Then to bus bar
  • From bus bar: 25A MIDI fuse to DC-DC (£10)

Total fusing cost: £38

Common Wiring Mistakes (And How I Made Them)

Mistake 1: Undersized Cable (Van #2 & #3)

What I did: Used 6mm² for 30A continuous load

Why it’s wrong: Cable got hot. Melted insulation.

Cost: £35 new cable + £45 terminals/heat shrink + terror

Fix: Used 10mm² cable. Perfect.

Lesson: Use cable sizing calculators. Add 20% safety margin.

Mistake 2: Poor Crimping (Van #1)

What I did: Used cheap crimpers (£8 from Pound Shop)

Result: Crimps were loose. One terminal pulled off while tightening.

Cost: £15 for proper ratchet crimpers

Lesson: Buy proper ratchet crimpers (£25-40). They make perfect crimps every time.

Mistake 3: No Fuse at Leisure Battery (Van #1)

What I did: Only fused at starter battery end

Why it’s wrong: If cable shorted near leisure end, fuse couldn’t protect

Cost: Lucky – didn’t have a short. But could have been disastrous.

Fix: Added fuse at leisure battery end

Lesson: BOTH ends must be fused

Mistake 4: Fuse Too Far From Battery (Van #2)

What I did: Fuse was 80cm from starter battery (ran cable through bulkhead first, then added fuse)

Why it’s wrong: 80cm of unfused cable is fire risk

Cost: Had to redo it. Pain in the arse.

Fix: Fuse right at battery (15cm cable)

Lesson: Fuse within 30cm maximum

Mistake 5: No Cable Protection (Van #1)

What I did: Bare cable along chassis (no split loom)

Result: After 6 months, cable chafed against sharp metal edge. Nearly shorted.

Cost: £8 for split loom to protect it

Lesson: Always use split loom protection where cable could chafe

Mistake 6: Ignoring Voltage Drop (Van #2)

What I did: Long thin cables (3.5m of 6mm² for 30A load)

Result: Voltage at leisure battery: 13.8V (alternator: 14.3V)

0.5V lost to cable resistance. Slower charging.

Cost: Efficiency loss

Fix: Shorter runs (routed better), thicker cables (10mm²)

Lesson: Minimize cable length. Size cable properly.

Mistake 7: Wrong Polarity (Briefly, Van #1)

What I did: Connected positive to negative terminal by mistake (briefly, caught it immediately)

Result: Big spark. Minor panic.

Cost: Just embarrassment (and slightly singed terminal)

Lesson: Double-check polarity before final connections. Red = positive. Black = negative.

Testing Your Installation

Before you drive anywhere, test properly.

Test 1: Voltage check (engine off)

Multimeter on DC voltage (20V range):

  • Starter battery: 12.5-12.8V (normal resting voltage)
  • Leisure battery: 12.5-13.3V (depending on charge state)

If either is below 12.0V, charge before testing.

Test 2: Polarity check

Confirm:

  • Positive terminals showing positive voltage
  • No voltage between positive and earth
  • No continuity between positive and negative (would indicate short)

Test 3: Engine start test

  1. Start engine
  2. Check DC-DC activates (LED or click)
  3. Measure voltage at leisure battery: Should rise to 14.4-14.6V within 1 minute
  4. Measure current (if possible): Should show charging current (10-30A depending on charger)

Test 4: Cable heat check

After 10 minutes running:

  • Touch all cables: Should be cool to slightly warm
  • Touch DC-DC: Should be warm (hand temperature)
  • Touch fuse holders: Should be cool
  • Touch terminals: Should be cool

If anything is hot (can’t touch for more than 2 seconds), STOP. Problem.

Test 5: Driving test

  1. Drive for 30 minutes
  2. Stop, recheck everything
  3. Drive for 2 hours
  4. Recheck everything

If all good after 2 hours driving, you’re sorted.

What I test every few months:

  • Terminals tight (vibration can loosen them)
  • Cables not chafed
  • No corrosion
  • Voltage still correct

Takes 10 minutes every 3 months. Worth it.

Troubleshooting Common Issues

Problem 1: Leisure Battery Not Charging

Symptoms:

  • Engine running but leisure voltage stays at 12.5V
  • No charging current
  • DC-DC LED off

Possible causes:

A) Starter voltage too low:

  • Check starter voltage with engine running
  • Should be 13.8V+
  • If lower, alternator problem or DC-DC won’t activate

B) Fuse blown:

  • Check both fuses (starter end and leisure end)
  • If blown, find out why before replacing

C) Wiring issue:

  • Check continuity from starter to DC-DC
  • Check continuity from DC-DC to leisure
  • Check all terminals tight

D) DC-DC charger failed:

  • Rare but possible
  • Check power LED (should light)
  • Check input voltage (should be 12-14V)
  • May need replacement

E) Wrong settings:

  • Check DC-DC programmed for correct battery type
  • Lithium needs lithium profile
  • AGM needs AGM profile

My troubleshooting process:

  1. Check voltages at starter battery
  2. Check voltages at DC-DC input
  3. Check voltages at DC-DC output
  4. Check voltages at leisure battery

This tells you where the problem is.

Problem 2: Starter Battery Being Drained

Symptoms:

  • Starter battery flat after 1-2 days parked
  • DC-DC or relay not isolating properly

Possible causes:

A) Relay stuck closed:

  • Check relay with multimeter (should open when voltage drops)
  • May be faulty (replace)

B) Reverse wiring:

  • Yeah, I did this
  • Check wiring diagram matches relay
  • Swap if wrong

C) DC-DC not isolating:

  • Most DC-DC chargers should isolate automatically
  • Check settings
  • May be faulty

D) Other loads on starter battery:

  • Check nothing else draining starter battery
  • Some van accessories stay powered

Problem 3: Cables Getting Hot

Symptoms:

  • Cable warm or hot to touch after 30 minutes driving
  • Smell of hot plastic
  • Melting insulation

Possible causes:

A) Cable undersized (most likely):

  • Check cable thickness vs current
  • Replace with thicker cable immediately
  • Don’t drive until fixed (fire risk)

B) Poor connection:

  • Loose terminal creates resistance creates heat
  • Check all terminals tight
  • Re-crimp if necessary

C) Damaged cable:

  • Check for crushed or damaged sections
  • Replace if damaged

This is dangerous. Stop immediately if cables get hot.

Problem 4: Slow Charging

Symptoms:

  • Takes 6+ hours driving to charge battery
  • Charging current very low (under 10A)

Possible causes:

A) Voltage drop from thin cables:

  • Measure voltage at DC-DC input vs starter battery
  • If more than 0.3V difference, cables too thin

B) Weak alternator:

  • Check alternator voltage (should be 13.8V+ at idle)
  • If lower, alternator weak or failing

C) DC-DC limited:

  • Check DC-DC rated current (18A, 30A, etc)
  • May need higher rated unit

D) Battery temperature:

  • Some chargers reduce current in cold weather
  • Check temperature sensor if fitted

Monitoring Your System

Worth having some way to see what’s happening.

Basic monitoring (£8-15):

  • Voltmeter near leisure battery
  • Shows voltage (approximate state of charge)
  • Cheap, simple, adequate

Better monitoring (£35-60):

  • Voltmeter + ammeter
  • Shows voltage and current
  • Can see charging happening

Professional monitoring (£150-200):

  • Battery monitor (Victron BMV-712, £185)
  • Shows voltage, current, Ah consumed, state of charge, time remaining
  • Bluetooth to phone app
  • This is what I have – worth every penny

My monitoring setup:

Victron BMV-712 (£185) connected to leisure battery with shunt (included).

Bluetooth app on phone shows:

  • Voltage: 13.2V
  • Current: -15A (discharging) or +18A (charging)
  • Power: -180W (discharging)
  • Consumed: 35Ah out of 105Ah
  • State of charge: 67%
  • Time remaining: 4.7 hours at current draw

Brilliant. Know exactly what’s happening always.

When driving, can see DC-DC charging (app shows +18A). When stopped, see consumption (app shows -5A to -15A depending on what’s running).

Worth the £185? Absolutely.

Real-World Performance: My Current System

Let me show you what actually happens with proper installation.

Van #4 setup:

  • Victron Orion 12/12-18 DC-DC charger
  • Fogstar Drift 105Ah lithium battery
  • 200W solar + Victron MPPT (separate system)
  • Wiring: 6mm² throughout, properly fused, professional crimping

Typical 3-day trip:

Day 1:

  • Start: Battery 85% (89Ah available)
  • Drive 2 hours to location
  • DC-DC charges: +36Ah (18A x 2 hours)
  • Arrive: Battery 100% (105Ah)
  • Evening use: Lights, fridge, laptop, water pump
  • Consumption: -22Ah
  • End of day: Battery 79% (83Ah)

Day 2:

  • Start: Battery 79% (83Ah)
  • No driving (parked up)
  • Solar: +45Ah (good sunny day)
  • Evening use: -20Ah
  • End of day: Battery 103% (105Ah – solar topped it up)

Day 3:

  • Start: Battery 100% (105Ah)
  • Use all day: -25Ah
  • Drive home: 1.5 hours
  • DC-DC charges: +27Ah
  • Arrive home: Battery 102% (full)

No issues. Never ran low. System perfect.

Winter 3-day trip (worst case):

Day 1:

  • Start: Battery 90% (95Ah)
  • Drive 2 hours
  • DC-DC charges: +36Ah
  • Arrive: Battery 100% (105Ah)
  • Evening use (heating): -35Ah
  • End of day: Battery 67% (70Ah)

Day 2:

  • Start: Battery 67% (70Ah)
  • No driving
  • Solar: +12Ah (cloudy winter day)
  • Evening use (heating): -33Ah
  • End of day: Battery 47% (49Ah)

Day 3:

  • Start: Battery 47% (49Ah)
  • Use morning: -15Ah
  • Battery now: 32% (34Ah)
  • Drive home: 1.5 hours
  • DC-DC charges: +27Ah
  • Arrive home: Battery 58% (61Ah)

Got slightly low but still 32Ah remaining (never at risk). System worked perfectly even in worst case.

Cost Breakdown: Complete Systems

Budget System (Split Charge Relay) – £145-£190

Components:

  • Split charge relay (30A): £35
  • Cable 6mm² (6m): £20
  • Fuses and holders (2x): £18
  • Terminals and heat shrink: £15
  • Split loom protection (3m): £8
  • Cable ties and misc: £8

Tools needed (if don’t have): £150-300

Total: £254-£490 (including tools)

Performance:

  • Charges at alternator voltage (13.8-14.3V)
  • Slow charging (4-6 hours for 100Ah from 50%)
  • Works with AGM only
  • Not suitable for smart alternators
  • Simple but limited

Standard System (18A DC-DC) – £280-£330

Components:

  • DC-DC charger 18A (Victron): £157
  • Cable 6mm² (6m): £20
  • Fuses and holders (2x): £28
  • Terminals and heat shrink: £20
  • Split loom protection (4m): £10
  • Cable ties and misc: £10

Tools needed (if don’t have): £150-300

Total: £395-£630 (including tools)

Performance:

  • Proper charging voltage (14.4-14.6V)
  • Fast charging (2.5-3 hours for 100Ah from 20%)
  • Works with any battery type
  • Works with smart alternators
  • Reliable and efficient

This is what I recommend.

Premium System (30A DC-DC + Monitoring) – £515-£575

Components:

  • DC-DC charger 30A (Victron): £210
  • Cable 10mm² (6m): £40
  • Fuses and holders (2x, larger): £35
  • Battery monitor (BMV-712): £185
  • Terminals and heat shrink: £25
  • Split loom protection (4m): £10
  • Cable ties and misc: £10

Tools needed (if don’t have): £150-300

Total: £665-£875 (including tools)

Performance:

  • Fast charging (1.5-2 hours for 200Ah from 20%)
  • Complete monitoring
  • Professional grade
  • Future-proof

For serious use or large batteries.

My Final Recommendations

After four vans, £565 in mistakes, one melted cable, and one killed alternator, here’s what I’d do:

For most people:

Buy Victron Orion 12/12-18 DC-DC charger (£157). Wire it with 6mm² cable properly fused. Done.

This is what works. Charges properly. Works with modern vans. Works with any battery type. Lasts forever.

Total cost: £280-330 (assuming you buy basic tools).

For those on tight budget:

Split charge relay is adequate IF:

  • Your van is pre-2015 (non-smart alternator)
  • You’re using AGM batteries
  • You drive 3+ hours between stops
  • Budget is really tight

Use decent relay (Durite, £35), proper cable sizes (10mm²), fuse both ends.

Total cost: £145-190.

For those with big batteries or full-time:

Victron Orion 12/12-30 (£210) + Battery monitor (£185).

Fast charging. Complete visibility.

Total cost: £515-575.

What I have and would buy again:

Victron Orion 12/12-18 (£157) 6mm² cable throughout (£20) Proper MIDI fuses both ends (£28) Victron BMV-712 monitor (£185)

Total: £390

Zero issues in 18 months. Would replicate exactly.

Final Thoughts

Split charging sounds simple. Connect alternator to leisure battery. Easy.

It’s not.

Get cable size wrong: Melted cables, potential fire. Get fusing wrong: No protection, potential fire. Wire relay backwards: Flat starter battery, stranded. Overload alternator: Dead alternator, £200-400 replacement.

I’ve made a few mistakes. Cost me a few quid and some genuinely scary moments.

But the knowledge gained means I can wire a system perfectly now. And you can too if you:

  1. Size cables properly (use calculators, add safety margin)
  2. Fuse both ends (within 30cm of batteries)
  3. Use DC-DC charger (not split charge relay, unless tight budget)
  4. Check everything twice before connecting
  5. Test properly before driving
  6. Monitor cables for heat on first few drives

The system I have now – £390 total – has been absolutely bulletproof for 18 months. Charges battery perfectly. No hot cables. No issues whatsoever.

If I built van #5 tomorrow, I’d buy exactly the same components and wire it exactly the same way. That’s how I know I finally got it right.

Now stop reading, buy a Victron Orion 12/12-18, wire it properly, and enjoy reliable charging that actually works.

Continue Reading
By
Batteries & Inverters

Best Campervan Batteries And Inverter Setup

No Comments
Best Campervan Batteries & Inverter Setup

I’ve built electrical systems in four campervans. The first one had a battery that died after four months because I cheaped out and used the wrong charger. The second had a 2000W inverter that I used maybe three times in two years. The third had solar panels that never performed anywhere near the claimed output. The fourth? Finally got it right. Mostly.

Between those four builds, I’ve wasted £680 on batteries that failed prematurely, £240 on an inverter I didn’t need, and countless hours troubleshooting electrical issues that were my own fault. But I’ve also learned what actually works in the real world versus what the marketing claims.

After 30 years as a maintenance manager working with building electrical systems, you’d think I’d know better. And for mains voltage (230V) systems, I do. But 12V DC systems in vans have their own peculiarities, and I’ve learned them all the expensive way.

This guide is everything I wish I’d known before I bought my first leisure battery. Not the theory from textbooks. Not the perfect-world calculations. The actual reality of powering a campervan in the UK, what genuinely works, and how to avoid the expensive mistakes I made.

In this post, I will discuss the Best Campervan Batteries And Inverter Setup, sharing insights from my experiences and the essential components for a reliable electrical system.

Why Your Electrical System Matters More Than You Think

A bad electrical system doesn’t just mean no lights. It means:

  • No fridge (food spoils, waste money)
  • No heating controller (diesel heaters need 12V)
  • No phone charging (can’t work remotely)
  • No water pump (no water pressure)
  • Sitting in darkness eating cold food like a cave dweller

Your electrical system is the most critical system after insulation. Get it wrong and your entire conversion is compromised.

What I’ve learned across four builds:

Van #1: Cheap 110Ah AGM battery (£95), basic split charge relay (£35), no solar. Battery died after 4 months because I was discharging it too deeply. Cost to replace: £150 for a better AGM. Total waste: £95 + time.

Van #2: Better 110Ah AGM (£180), DC-DC charger (£165), 100W solar (£180). Much better but still ran out of power in winter. AGM was too small for my actual usage.

Van #3: 200Ah AGM (£420), DC-DC charger, 200W solar (£280). Heavy (63kg), expensive, but worked reasonably well. Lasted 3.5 years before capacity dropped below 50%.

Van #4 (current): 105Ah lithium LiFePO4 (£449), Victron DC-DC charger (£157), 200W solar (£180), Victron MPPT controller (£85). Finally perfect. Indefinite power in summer, 2-3 days without charging in winter. Worth every penny.

Total money wasted learning: £680 on failed/inadequate batteries + £240 on wrong components = £920

But the knowledge gained: Priceless. Now I know exactly what works.

Understanding Your Actual Power Needs

Before you buy anything, you need to know how much power you actually use. Not what you think you’ll use. What you ACTUALLY use.

Everyone designs for massive power requirements they never need. I did this on van #2. Planned for laptop work all day, TV at night, electric kettle, hairdryer, the works. Reality? Used the laptop 2 hours max, never used the TV, used the gas kettle instead.

My Actual Daily Power Consumption (Van #4, Regular Use)

Let me show you real numbers from my current setup over a typical 3-day trip:

Lighting (LED):

  • Interior lights: 15W total (3 lights x 5W)
  • Average use: 4 hours per day
  • Daily consumption: 15W x 4h = 60Wh = 5Ah @ 12V

12V Fridge (Alpicool C20, 20L compressor):

  • Running: 45W
  • Cycling: 50% duty cycle (on/off)
  • Daily consumption: 45W x 12h = 540Wh = 45Ah @ 12V

Water Pump (Shurflo):

  • Running: 40W
  • Average use: 15 minutes per day
  • Daily consumption: 40W x 0.25h = 10Wh = 0.8Ah @ 12V

Phone Charging (2 phones):

  • Each phone: 15Wh
  • Daily: 30Wh = 2.5Ah @ 12V

Laptop Charging:

  • Laptop: 65W for 2 hours
  • Daily: 130Wh = 11Ah @ 12V

Diesel Heater (Vevor 5kW):

  • Running low: 15W
  • Running high: 35W (startup: 100W for 2 minutes)
  • Average winter use: 8 hours on low
  • Daily consumption: 15W x 8h = 120Wh = 10Ah @ 12V

Misc (USB devices, speakers, etc.):

  • Estimate: 20Wh = 1.7Ah @ 12V

Total Daily Summer Consumption: ~65Ah Total Daily Winter Consumption (with heating): ~75Ah

Reality check: I overestimated when planning. I thought I’d use 90-100Ah daily. Actual usage is 30% less.

How To Calculate YOUR Power Needs

Step 1: List every 12V device

DeviceWattsHours/dayWh/dayAh/day
LED lights (total)15W4605.0
Compressor fridge45W12 (cycling)54045.0
Water pump40W0.25100.8
Phone charging15W2302.5
……………

Step 2: Add 20% contingency

You’ll always use more than planned. Things you forgot. Inefficiencies.

Step 3: Decide on days of autonomy

  • Weekend warrior: 2 days (you’ll drive between trips)
  • Regular user: 3 days (comfortable buffer)
  • Off-grid living: 5-7 days (serious battery bank needed)

Step 4: Calculate required battery capacity

My example:

  • Daily use: 75Ah (winter, worst case)
  • Days autonomy: 3 days
  • Total: 75Ah x 3 = 225Ah

BUT battery type matters here:

  • AGM/Gel: Can only use 50% safely = Need 450Ah of AGM
  • Lithium: Can use 100% safely = Need 225Ah of lithium (or 105Ah with solar)

This is why lithium is actually cheaper per usable Ah.

Battery Types: The Honest Comparison

I’ve used all three main types. Here’s what actually happens in real life.

AGM (Absorbed Glass Mat) Batteries

What they are: Lead-acid batteries with acid absorbed in glass mat. Sealed, no maintenance.

Costs:

  • 110Ah: £150-£250 (Varta, Banner, Exide)
  • 200Ah: £350-£500

Real-world specs:

  • Usable capacity: 50% (discharge beyond this = damage)
  • Weight: 30-32kg per 110Ah
  • Lifespan: 300-500 cycles (2-4 years typical use)
  • Charging: Need 14.4-14.7V (most alternators do 14.2V – barely adequate)
  • Self-discharge: 3-5% per month

My experience:

Van #1: Budget 110Ah AGM (£95, no-name brand from eBay)

  • Died after 4 months
  • Why: Cheap, poor quality, I was discharging to 30% regularly (too deep)
  • Lesson: Don’t buy cheap AGM

Van #2: Better 110Ah AGM (£180, Varta)

  • Lasted 18 months
  • Why it failed: 110Ah with only 55Ah usable wasn’t enough for my usage (60-70Ah daily)
  • I was cycling it 80-100% depth daily
  • That’s about 150 cycles – battery was done

Van #3: 200Ah AGM (£420, Banner)

  • Lasted 3.5 years (about 400 cycles)
  • Performed as expected
  • But: Heavy (63kg), took up loads of space, slow to charge

Pros:

  • Cheap upfront
  • Available everywhere
  • Work with simple charging systems
  • Well understood technology

Cons:

  • Heavy (63kg for 200Ah)
  • Only 50% usable capacity
  • Slow to charge (need 8-12 hours for full charge)
  • Die quickly if discharged too deeply
  • Limited cycle life (300-500 cycles)
  • Need good ventilation (they off-gas hydrogen when charging)

Verdict: Adequate for budget builds or very light use. Not ideal for regular use or off-grid camping. I wouldn’t buy AGM again.

Best AGM if you must:

  • Varta LFD90 (90Ah): £185
  • Banner Energy Bull (110Ah): £215
  • Exide Equipment Gel (80Ah): £195

Gel Batteries

What they are: Lead-acid with acid in gel form. Sealed, maintenance-free.

Costs:

  • 80Ah: £180-£280
  • 110Ah: £250-£380

Real-world specs:

  • Usable capacity: 60% (slightly better than AGM)
  • Weight: Similar to AGM (28-30kg per 110Ah)
  • Lifespan: 400-600 cycles
  • Charging: Need precise 14.1-14.4V (fussy about voltage)
  • Self-discharge: 1-3% per month (better than AGM)

My experience:

Never used Gel in a van. I tested one in a mate’s van (Sonnenschein 80Ah, £240).

What I observed:

  • Slightly better than AGM for deep discharge
  • Very fussy about charging voltage (his DC-DC needed adjustment)
  • Expensive for not much benefit over AGM
  • Still heavy

Pros:

  • Better deep discharge tolerance than AGM
  • Lower self-discharge
  • Longer lifespan than AGM
  • Better for extreme temperatures

Cons:

  • Expensive
  • Still heavy
  • Fussy about charging voltage
  • Still only 60% usable capacity
  • Hard to find in large sizes

Verdict: Marginal improvement over AGM for significant extra cost. Not worth it. If you’re spending this much, buy lithium.

Lithium LiFePO4 (Lithium Iron Phosphate)

What they are: Modern lithium battery chemistry. Completely different from lead-acid.

Costs:

  • 100Ah: £380-£550 (Fogstar, Roamer, ECO-WORTHY)
  • 100Ah: £550-£750 (Victron, Renogy, Battle Born – premium brands)
  • 200Ah: £700-£1,200

Real-world specs:

  • Usable capacity: 100% (can use full capacity safely)
  • Weight: 11-13kg per 100Ah (about 1/3 of AGM)
  • Lifespan: 2,000-5,000 cycles (8-12 years typical use)
  • Charging: Need proper lithium charging profile (14.4-14.6V)
  • Self-discharge: <3% per year (virtually none)

My experience:

Van #4: Fogstar Drift 105Ah (£449)

I resisted lithium for ages. “Too expensive,” I thought. £449 versus £180 for AGM? That’s 2.5x the cost.

But when you actually calculate cost per usable Ah over lifespan:

AGM (110Ah):

  • Cost: £180
  • Usable: 55Ah
  • Lifespan: 400 cycles
  • Cost per cycle: £0.45
  • Cost per usable Ah per cycle: £0.0082

Lithium (105Ah):

  • Cost: £449
  • Usable: 105Ah
  • Lifespan: 3,000 cycles (conservative)
  • Cost per cycle: £0.15
  • Cost per usable Ah per cycle: £0.0014

Lithium is actually 6x cheaper per usable Ah over its lifetime.

Real-world performance after 18 months:

  • Can discharge to 0% without damage (I keep it above 20% anyway)
  • Charges from 20% to 100% in 2.5 hours (versus 8 hours for AGM)
  • Weighs 12kg versus 32kg for equivalent AGM
  • Zero capacity loss (voltage still shows 13.3V after 18 months)
  • Handles 100A loads without voltage sag (tried running 1200W inverter)
  • Works perfectly in Scottish winter (-5°C) and Spanish summer (35°C)

Pros:

  • 100% usable capacity
  • Lightweight (1/3 of AGM)
  • Fast charging (3-5 hours vs 8-12 hours)
  • Long lifespan (2,000-5,000 cycles)
  • Maintenance-free
  • No voltage sag under load
  • No off-gassing (no ventilation needed)
  • Better for batteries in cold or hot weather

Cons:

  • Expensive upfront
  • Need proper lithium charger (DC-DC or MPPT with lithium profile)
  • More complex BMS (Battery Management System)
  • Can’t charge below 0°C (BMS prevents this)
  • Fire risk if damaged (though LiFePO4 is safest lithium chemistry)

Common lithium myths I believed (all false):

Myth 1: “Lithium catches fire easily” Reality: LiFePO4 is incredibly stable. You’d have to really abuse it (short circuit, massive overcharge, puncture). AGM can off-gas hydrogen which is explosive. Both are safe if used correctly.

Myth 2: “Lithium dies in cold weather” Reality: Can’t charge below 0°C but works fine. I’ve used mine at -5°C. Just drive during the day (warms up from charging) or wait until above 0°C.

Myth 3: “Lithium needs expensive charging systems” Reality: You need a charger with lithium profile. A good DC-DC is £120-180. You needed a charger anyway.

Myth 4: “Lithium is dangerous to work with” Reality: Same precautions as any battery. Don’t short circuit. Fuse properly. Use correct cable sizes. I’m a maintenance manager – I know electrical safety. Lithium isn’t scary if you’re not an idiot.

Best lithium batteries I’d recommend:

Budget (£380-£450):

  • Fogstar Drift 105Ah: £449 (what I use)
  • Roamer 100Ah: £410
  • ECO-WORTHY 100Ah: £385

These are Chinese-made with UK support. Work brilliantly. Fogstar has excellent UK customer service.

Premium (£550-£750):

  • Victron 100Ah: £695
  • Renogy 100Ah: £625
  • Battle Born 100Ah: £750

Better warranty, premium components, slight performance edge. Worth it if you’re full-timing or want absolute best.

Verdict: Buy lithium. Seriously. The upfront cost hurts but it’s genuinely cheaper long-term and performs massively better. If I was building van #5 tomorrow, I’d buy Fogstar Drift 105Ah again without hesitation.

Charging Your Battery: What Actually Works

Battery is half the story. Charging is the other half. Get this wrong and even the best battery fails.

Method 1: Split Charge Relay (The Budget Option)

What it is: Simple relay that connects your leisure battery to your alternator when engine is running.

Cost: £30-£60

How it works:

  1. Engine starts
  2. Relay detects voltage rise (13.5V+)
  3. Connects leisure battery to alternator
  4. Both batteries charge
  5. Engine stops
  6. Relay disconnects (prevents leisure draining starter)

Pros:

  • Cheap
  • Simple
  • Easy to install
  • Works with any battery (AGM, Gel, Lithium with right voltage)

Cons:

  • Inefficient charging (only charges when engine running at decent RPM)
  • Can overcharge (alternator voltage varies)
  • Can undercharge (many alternators only hit 14.2V – too low for proper AGM charging)
  • Doesn’t isolate properly under all conditions
  • Can drain starter battery if relay fails
  • Slow charging (limited by alternator voltage)

My experience:

Van #1: Used a basic split charge relay (£35, Ring Automotive).

Worked. Technically. But:

  • AGM never got fully charged (alternator was 14.2V, needed 14.7V)
  • This contributed to battery dying after 4 months
  • Slow charging (took 6+ hours driving to charge 110Ah from 50%)

Verdict: Only use this if:

  • You’re on a very tight budget (under £500 total for electrics)
  • You’re using AGM (not lithium – wrong charging profile)
  • You drive a lot between stops (4+ hours)
  • Your alternator is in good condition

Better option: Save another £100 and buy a DC-DC charger.

Method 2: DC-DC Battery Charger (The Right Way)

What it is: Intelligent charger that converts alternator voltage (12-14V) to optimal charging voltage for your battery (14.2-14.6V).

Cost: £100-£220

How it works:

  1. Monitors both starter and leisure batteries
  2. Only activates when starter is charged (13.5V+)
  3. Draws power from alternator
  4. Converts to optimal voltage for leisure battery type
  5. Charges in proper 3-stage profile (bulk, absorption, float)
  6. Protects both batteries

Pros:

  • Proper charging profile (extends battery life)
  • Works with AGM, Gel, and Lithium (selectable profiles)
  • Fast charging (full current even at idle)
  • Protects starter battery (won’t drain it)
  • Protects leisure battery (won’t overcharge)
  • Smart (adjusts to battery condition)

Cons:

  • More expensive (£100-220)
  • Slightly more complex to install
  • Needs good alternator (old weak alternators struggle)

Popular models:

Budget (£100-£140):

  • Renogy 20A DC-DC: £105
  • CTEK D250SE: £125
  • Sterling BB1230: £135

Mid-range (£150-£180):

  • Victron Orion 12/12-18: £157 (what I use)
  • Renogy 40A DC-DC: £165
  • CTEK D250SA + Smartpass: £180

Premium (£190-£220):

  • Victron Orion 12/12-30: £210
  • Sterling BB1260: £215

Amperage matters:

  • 18A charger = 18Ah per hour (5.8 hours for 105Ah battery from 0%)
  • 30A charger = 30Ah per hour (3.5 hours for 105Ah battery from 0%)

But you need sufficient alternator capacity. My Transit has a 150A alternator. Using 30A for leisure charging is fine. Smaller vans might struggle.

My experience:

Van #2 & #3: Used a basic DC-DC (can’t remember brand, £120). Worked well. Better than split charge relay. AGM charged properly.

Van #4: Victron Orion 12/12-18 (£157). Perfect. Charges my lithium battery properly. Can monitor via Bluetooth app (shows charging voltage, current, state). Excellent bit of kit.

Installation tips:

Location: Close to leisure battery (within 1m). Shorter cable = less voltage drop.

Cable sizing:

  • 18A charger needs 4mm² cable minimum
  • 30A charger needs 6mm² cable minimum
  • Use thicker if cable run is longer

Fusing: Must have fuse at both ends:

  • Main fuse near starter battery (30A for 18A charger)
  • Secondary fuse near leisure battery (25A)

Grounding: Negative cable direct to chassis near batteries. Not through van body.

Verdict: This is what you should buy. Victron Orion 12/12-18 (£157) for most people. Victron Orion 12/12-30 (£210) if you have a big battery and good alternator.

Method 3: Solar Panels (The Game-Changer)

What they are: Photovoltaic panels on your roof converting sunlight to electricity.

Cost: £180-£600 (panel + controller + mounting)

Typical setup:

  • 100W panel: £90-£150
  • 200W panel: £180-£280
  • MPPT controller: £60-£150
  • Mounting brackets: £25-£45
  • Cable and connectors: £20-£40

What solar actually gives you (UK reality):

I have 200W solar (2 x 100W panels). Here’s real performance:

Summer (May-August):

  • Perfect day: 80-90Ah
  • Cloudy day: 40-50Ah
  • Overcast: 20-30Ah
  • Average: 60Ah/day

Spring/Autumn (March-April, September-October):

  • Perfect day: 50-60Ah
  • Cloudy day: 25-35Ah
  • Overcast: 10-20Ah
  • Average: 35Ah/day

Winter (November-February):

  • Perfect day: 20-30Ah
  • Cloudy day: 10-15Ah
  • Overcast: 5-10Ah
  • Average: 15Ah/day

Important: Marketing claims (100W = 500Wh/day) are based on California desert with perfect conditions. UK reality is 30-40% of that.

Solar controller types:

PWM (Pulse Width Modulation):

  • Cost: £15-£40
  • Efficiency: 70-80%
  • Simple technology
  • Don’t buy these. Waste of money.

MPPT (Maximum Power Point Tracking):

  • Cost: £60-£150
  • Efficiency: 93-97%
  • Smart technology
  • Extracts maximum power from panel
  • Worth the extra cost

My solar journey:

Van #2: 100W panel (£90) + cheap PWM controller (£25)

  • Performed poorly (maybe 30Ah on good summer day)
  • Didn’t understand why at the time
  • Controller was the bottleneck

Van #3: 200W panel (£180) + Better PWM controller (£45)

  • Better but still disappointing
  • Maybe 45Ah on good summer day
  • Still using PWM (idiot)

Van #4: 200W panel (£180) + Victron MPPT 75/15 (£85)

  • Night and day difference
  • 60Ah on good summer day
  • Even gets 15-20Ah on winter days

The MPPT controller made 30-40% difference in output. £85 well spent.

Best MPPT controllers:

Budget (£60-£90):

  • Renogy Rover 20A: £65
  • EPSolar 20A: £75

Mid-range (£85-£130):

  • Victron MPPT 75/15: £85 (what I use)
  • Renogy Rover Elite 40A: £120

Premium (£150-£200):

  • Victron MPPT 100/30: £165
  • Morningstar TriStar: £195

Solar panel recommendations:

Flexible panels (£90-£180):

  • Easier to fit (curve with roof)
  • Lighter
  • More expensive
  • Lower efficiency (15-17%)
  • Shorter lifespan (5-8 years)

Rigid panels (£90-£200):

  • Need proper mounting
  • Heavier
  • Cheaper
  • Better efficiency (18-21%)
  • Longer lifespan (20-25 years)

I use rigid panels (Renogy 100W x2, £180 total). Mounted with brackets and Sikaflex. Still going strong after 3 years.

Verdict: Solar is brilliant in summer, mediocre in winter. If you camp April-October primarily, solar gives you indefinite power. If you camp year-round, solar helps but you’ll still need to drive to charge in winter.

Budget £250-£350 for 200W solar with MPPT controller.

Method 4: Mains Hook-Up Charging (Campsite Power)

What it is: Plug into 230V campsite supply and charge batteries via mains charger.

Cost: £60-£150 for charger

When you need this:

  • You use campsites regularly
  • You want occasional full charge
  • You’re parked up long-term

Charger types:

Basic (£60-£90):

  • CTEK MXS 5.0: £72 (what I have)
  • Noco Genius 10: £85

Smart (£110-£150):

  • Victron Blue Smart 12/15: £125
  • CTEK MXS 10: £140

My setup:

CTEK MXS 5.0 (£72). Lives in the van. Use it maybe 10 times a year when on campsites with electric hook-up (EHU).

Charges my 105Ah lithium from 20% to 100% in about 5 hours. Works fine.

Verdict: Nice to have, not essential. Buy if you use campsites regularly. Skip if you’re wild camping only.

Inverters: What You Actually Need (Versus What Marketing Says)

An inverter converts 12V DC (battery) to 230V AC (normal plug sockets).

The marketing: “You need a 2000W pure sine wave inverter for £300!”

The reality: Most people need a 600W inverter or no inverter at all.

Do You Even Need An Inverter?

What inverters are actually useful for:

  • Charging laptops (65-90W)
  • Running mains phone/camera chargers (10-20W)
  • Occasional power tool use (200-600W)
  • Hairdryer (requires 1000W+ inverter)

What you DON’T need an inverter for:

  • Charging phones (use 12V USB sockets – £8)
  • Running lights (use 12V LED lights)
  • Running fridge (use 12V compressor fridge)
  • Boiling kettle (use gas kettle – electric kettles need 2000W+)
  • Making toast (use gas stove or campfire)

My inverter journey:

Van #1: No inverter. Used 12V USB sockets. Worked fine.

Van #2: Bought a 2000W pure sine wave inverter (£285). Used it maybe 8 times in 2 years:

  • Laptop charging: 3 times (could’ve used 12V car charger)
  • Power drill: 2 times (could’ve borrowed mains on campsite)
  • Electric razor: 3 times (should’ve bought a battery one)

Total waste: £285. Sold it for £140. Lost: £145.

Van #3: Bought a 600W inverter (£85). Much more sensible. Used it regularly for laptop charging.

Van #4: Kept the 600W inverter. Use it 3-4 times per week for laptop charging. Perfect size.

Inverter Types: Pure Sine vs Modified Sine

Modified Sine Wave:

  • Cost: £30-£80
  • Output: Stepped approximation of sine wave
  • Works for: Basic electronics, resistive loads (lights, kettles)
  • Doesn’t work for: Sensitive electronics, some laptop chargers, motors
  • Makes buzzing sound
  • Less efficient

Pure Sine Wave:

  • Cost: £60-£250
  • Output: Smooth sine wave (like mains power)
  • Works for: Everything
  • Silent
  • More efficient
  • This is what you should buy

Don’t buy modified sine wave inverters. The £30 saving isn’t worth the compatibility issues and noise.

Inverter Sizing: What You Actually Need

Small (300-600W): £60-£120

  • Laptop charging (65-90W)
  • Phone/camera chargers (10-30W)
  • Small power tools (200-400W)
  • This is what most people need

Medium (1000-1500W): £140-£220

  • Hairdryer (1000-1200W)
  • Coffee machine (800-1200W)
  • Microwave (800-1000W)
  • Only if you actually use these

Large (2000-3000W): £250-£450

  • Electric kettle (2000-3000W)
  • Toaster (900-1500W)
  • Powerful power tools (1500W+)
  • Rarely needed in van

My recommendation:

600W pure sine wave inverter (£80-£120). This covers laptop, phone charging, and light power tool use.

Good options:

  • LVYUAN 600W: £75
  • Giandel 600W: £95
  • Renogy 700W: £110

I use a Giandel 600W (£95). Works perfectly. Charges my laptop (65W), partner’s laptop (45W), phones, camera batteries. That’s all we need.

Efficiency reality check:

Inverters aren’t 100% efficient. Typical efficiency: 85-92%.

Example: Charging a 65W laptop

  • Laptop draws 65W from inverter
  • Inverter draws 65W ÷ 0.9 efficiency = 72W from battery
  • At 12V: 72W ÷ 12V = 6A from battery
  • For 2 hours: 12Ah from battery

Compare to:

  • Using 12V laptop charger: 65W ÷ 12V = 5.4A = 10.8Ah for 2 hours
  • Slightly better but need specialist 12V charger (£25-£45)

Verdict: Buy a 600W pure sine wave inverter (£80-120) if you need laptop charging or occasional 230V power. Skip it entirely if you can use 12V alternatives for everything.

Inverter Installation Tips

Location:

  • Close to battery (within 2m)
  • Well-ventilated (they get hot under load)
  • Accessible (you’ll turn it on/off)
  • NOT in a sealed cupboard (fire risk)

Cable sizing (critical):

Undersized cables = voltage drop, power loss, fire risk.

For 600W inverter:

  • Maximum current: 600W ÷ 12V = 50A
  • Cable needed: 10mm² minimum (I use 16mm²)
  • Length: Keep under 2m if possible

For 1500W inverter:

  • Maximum current: 1500W ÷ 12V = 125A
  • Cable needed: 25mm² minimum
  • Length: Keep under 1.5m

Fusing (absolutely essential):

Main fuse between battery and inverter:

  • 600W inverter: 60A fuse
  • 1500W inverter: 150A fuse

Use ANL fuses or MEGA fuses. Not automotive blade fuses (too small).

My setup:

Giandel 600W inverter connected with 16mm² cable (1.2m length). 60A ANL fuse at battery end. Inline switch to turn inverter on/off (saves standby drain).

Complete System Design: Three Levels

Let me show you three complete electrical systems at different budget levels.

Budget System (£580-£780)

For: Weekend warriors, tight budget, minimal power needs

Battery:

  • 110Ah AGM (Varta LFD90): £185

Charging:

  • Split charge relay: £35
  • 100W solar panel: £120
  • PWM controller: £35
  • Shore power charger (CTEK MXS 5.0): £72

Distribution:

  • 6-way fuse box: £35
  • Cable (various): £40
  • Fuses and connectors: £25

Outputs:

  • 4x LED lights: £40
  • 2x 12V sockets: £12
  • 2x twin USB sockets: £20

No inverter (use 12V for everything)

Total: £619

Performance:

  • 55Ah usable capacity (50% of 110Ah)
  • 1-2 days autonomy (light use only)
  • Slow charging (8+ hours from alternator)
  • Summer solar: 20-30Ah/day
  • Winter solar: 5-10Ah/day

Verdict: Bare minimum. Works for occasional weekend use with minimal electronics. Not adequate for regular use or working remotely.

Standard System (£1,180-£1,450) – RECOMMENDED

For: Regular users, comfortable power, year-round camping

Battery:

  • 105Ah Lithium (Fogstar Drift): £449

Charging:

  • Victron Orion 12/12-18 DC-DC: £157
  • 200W solar panel (2x100W): £180
  • Victron MPPT 75/15: £85
  • Shore power charger (CTEK MXS 5.0): £72

Distribution:

  • 12-way fuse box: £60
  • Cable (various sizes): £85
  • Fuses, terminals, connectors: £45

Outputs:

  • 4x LED lights: £45
  • 2x 12V sockets: £12
  • 2x twin USB sockets: £20
  • 600W pure sine inverter: £95

Optional:

  • Battery monitor (Victron BMV-712): £185

Total: £1,305 (or £1,490 with battery monitor)

Performance:

  • 105Ah usable capacity (100% of 105Ah)
  • 2-3 days autonomy (normal use)
  • Fast charging (3-4 hours from alternator)
  • Summer solar: 50-70Ah/day (indefinite autonomy)
  • Winter solar: 15-25Ah/day (extends autonomy significantly)

This is what I have. Works brilliantly. Perfect for 80-100 nights/year use. Can go off-grid for a week in summer. 3-4 days in winter.

Verdict: Sweet spot. Adequate power for real use. Fast charging. Solar makes huge difference. This is what I’d recommend for most people.

Premium System (£2,100-£2,600)

For: Full-time or near-full-time living, maximum power, redundancy

Battery:

  • 200Ah Lithium (2x100Ah in parallel): £900 OR
  • Victron 200Ah Lithium: £1,280

Charging:

  • Victron Orion 12/12-30 DC-DC: £210
  • 400W solar (4x100W or 2x200W): £380
  • Victron MPPT 100/30: £165
  • Victron Blue Smart mains charger 12/25: £185

Distribution:

  • Premium fuse box with monitoring: £120
  • Cable (various, larger sizes): £140
  • Fuses, terminals, connectors: £70

Outputs:

  • 6x LED lights: £65
  • 3x 12V sockets: £18
  • 3x twin USB sockets: £30
  • 1500W pure sine inverter: £220
  • Battery monitor (Victron BMV-712): £185

Total: £2,688 (with 2x100Ah Fogstar) Total: £3,068 (with Victron 200Ah)

Performance:

  • 200Ah usable capacity
  • 4-6 days autonomy (normal use)
  • Very fast charging (2-3 hours from alternator)
  • Summer solar: 100-140Ah/day (more than you’ll use)
  • Winter solar: 30-50Ah/day (near-indefinite autonomy)

Verdict: This is full-time living spec. Massive battery, loads of solar, fast charging, 1500W inverter for hairdryer/coffee machine. Overkill for weekend use but perfect for 200+ nights/year.

My Actual System (Van #4) Detailed

Since this is what actually works in real life, let me break down every component and cost.

Battery:

  • Fogstar Drift 105Ah LiFePO4: £449
  • Rated 3000+ cycles
  • 18 months old, zero capacity loss

Charging:

  • Victron Orion 12/12-18 DC-DC: £157
  • Charges from alternator while driving
  • Victron MPPT 75/15 controller: £85
  • 2x Renogy 100W rigid solar panels: £180
  • CTEK MXS 5.0 shore power charger: £72

Distribution:

  • 12-way bus bar fuse box: £62
  • Main isolator switch: £18
  • 100A ANL fuse (main): £12
  • Various fuses and holders: £28

Wiring:

  • 16mm² battery to fuse box (2m): £18
  • 10mm² fuse box to inverter (1.5m): £12
  • 6mm² solar to MPPT (8m): £22
  • 4mm² DC-DC to battery (2m): £8
  • 2.5mm² lighting circuits (15m): £14
  • 2.5mm² 12V sockets (10m): £9
  • Various connectors and terminals: £35

Outputs:

  • 4x LED strip lights (5W each): £45
  • 2x 12V cigarette sockets: £12
  • 2x twin USB sockets (2.4A each): £20
  • Giandel 600W pure sine inverter: £95

Monitoring:

  • Victron BMV-712 battery monitor: £185
  • Monitors voltage, current, Ah consumed, time remaining
  • Bluetooth to phone app

Total system cost: £1,538

Performance over 18 months:

Summer (June-August):

  • Daily use: 60-70Ah
  • Solar generation: 50-80Ah/day
  • Result: Never needed to drive to charge
  • Battery stays 80-100% constantly

Winter (December-February):

  • Daily use: 70-80Ah (heating + lights longer)
  • Solar generation: 10-25Ah/day
  • Result: Drive every 2-3 days (1-2 hours) to recharge
  • Battery cycles 80% → 30% → 80%

Spring/Autumn:

  • Daily use: 60-70Ah
  • Solar generation: 30-50Ah/day
  • Result: Drive every 3-4 days to top up
  • Very comfortable

Actual cycle count after 18 months: ~180 cycles (monitoring shows this)

Estimated lifespan: 3000 cycles = 16+ years at current usage

Problems: None. Zero issues. System has worked flawlessly.

What I’d change: Nothing. This setup is perfect for my use (80-100 nights/year, mix of camping and working remotely).

Common Electrical Mistakes (That I Made)

Mistake 1: Undersized Battery (Van #1)

What I did: 110Ah AGM, using 60-70Ah daily

Math: 60Ah used ÷ 55Ah usable = 109% of capacity daily

Result: Deep cycling to 30% remaining every day. Battery died after 4 months (120 cycles).

Cost: £95 wasted + £150 replacement

Lesson: Size battery for actual usage plus 30% buffer. Don’t deep cycle AGM daily.

Mistake 2: Oversized Inverter (Van #2)

What I did: Bought 2000W inverter thinking I needed it

Reality: Maximum load ever used was 90W (laptop)

Cost: £285 for inverter, sold for £140 = £145 loss

Lesson: Calculate actual maximum load. Most people need 300-600W, not 2000W.

Mistake 3: Cheap PWM Controller (Van #2 & #3)

What I did: Used PWM controllers (£25-45) instead of MPPT

Result: Got 60-70% of possible solar output

Lost generation: 15-25Ah per day in summer

Cost over 2 years: Equivalent to £100-150 in campsite fees or fuel for charging

Lesson: MPPT controller (£85) pays for itself in 1-2 years. Don’t cheap out.

Mistake 4: Cable Too Small (Van #1)

What I did: Used 6mm² cable from battery to fuse box (3m length)

Load: 40A occasionally

Voltage drop: 40A x 3m x 0.0044 (resistance) = 0.53V drop

Result: Voltage at fuse box was 12.2V instead of 12.7V. Inefficient.

Cost: Not huge but wasted power

Lesson: Use proper cable sizing calculators. Don’t guess.

Mistake 5: No Battery Monitoring (Van #1-3)

What I did: Relied on voltage readings to estimate battery state

Problem: Voltage is a terrible indicator of lithium battery state

Result: Never knew actual state of charge. Overestimated or underestimated constantly.

Fix: Bought Victron BMV-712 (£185) for van #4

Lesson: Battery monitor is worth it. Know exactly what’s happening with your power.

Mistake 6: Fuse Box Too Small (Van #1)

What I did: 6-way fuse box

Reality: Needed 10 circuits (lights x4, 12V sockets x2, fridge, water pump, diesel heater, inverter)

Result: Had to add inline fuse holders (messy, not ideal)

Cost: £15 for inline fuses, plus time to redo

Lesson: Buy 12-way fuse box (£60) even if you only need 8 circuits initially. You’ll add more.

Mistake 7: Battery Location Wrong (Van #2)

What I did: Put 63kg AGM battery in back corner (1.5m from fuse box)

Result: Needed 2.5m cable run. Voltage drop. Also weight distribution was off (tail heavy).

Cost: Extra cable (£28), handling issues

Lesson: Battery should be central and low for weight distribution, close to fuse box for efficiency.

Critical Safety Stuff (Don’t Skip This)

I’m a maintenance manager. I’ve seen electrical fires. Don’t be an idiot with your van electrics.

Essential safety components:

1. Main fuse/breaker (100-150A):

  • Between battery positive and everything else
  • ANL fuse or MEGA fuse
  • Close to battery (within 30cm)
  • This prevents cable fires if there’s a short
  • Cost: £12-25

2. Circuit fuses:

  • Every circuit must be fused
  • Size fuse to cable rating, not device rating
  • Use automotive blade fuses (10A, 15A, 20A, 30A)
  • Cost: £2-5 per circuit

3. Isolator switch:

  • Main switch to disconnect battery
  • Use when working on system
  • Use when van stored long-term
  • Cost: £18-35

4. Proper cable sizing:

  • Use cable sizing calculators
  • Account for length and current
  • Bigger is always safer
  • Cost: Variable but worth it

Cable size guide (12V, 3m max length):

  • 0-10A: 1.5mm²
  • 10-20A: 2.5mm²
  • 20-40A: 4mm²
  • 40-60A: 6mm²
  • 60-100A: 10mm²
  • 100-150A: 16mm²
  • 150-200A: 25mm²

5. Quality terminals:

  • Crimp properly (ratchet crimpers)
  • Heat shrink over connections
  • No twisted wire connections
  • Cost: £30-50 for assortment

6. Ventilation:

  • AGM/Gel batteries off-gas hydrogen when charging
  • Lithium doesn’t but still needs ventilation for heat
  • Battery compartment must vent to outside
  • Cost: £15-25 for vent

7. Fire extinguisher:

  • Keep one near battery area
  • ABC or CO2 type
  • Check annually
  • Cost: £25-40

Electrical safety checklist before first use:

  • [ ] Main fuse installed and correct rating
  • [ ] All circuits fused correctly
  • [ ] All cables correct size for current
  • [ ] All terminals crimped properly
  • [ ] No exposed connections
  • [ ] Battery secured (can’t move in crash)
  • [ ] Isolator switch installed and accessible
  • [ ] Ventilation adequate
  • [ ] Fire extinguisher accessible
  • [ ] Tested all circuits with multimeter
  • [ ] No shorts or voltage drops
  • [ ] System works under load

Don’t:

  • Wire directly to battery without fusing (fire risk)
  • Use automotive wire for high current (too thin)
  • Twist wires together (connections fail)
  • Over-fuse circuits (cables overheat)
  • Put battery in sealed box (gas buildup)
  • Work on live circuits (get shocked)
  • Assume anything is safe without testing

Tools Needed for Electrical Work

Essential:

  • Multimeter (£15-45)
  • Wire strippers (£15-25)
  • Ratchet crimpers (£25-40)
  • Cable cutters (£12-18)
  • Screwdrivers (£15-25)
  • Hole saw set for cable entry (£25-35)

Useful:

  • Heat gun (£20-40)
  • Cable tie gun (£12)
  • Label maker (£25)
  • Electrical tape (£5)

Total: £145-250

My Final Recommendations

After four van builds and £920 wasted on wrong choices, here’s what I’d buy today:

For most people (£1,200-£1,500):

Battery: Fogstar Drift 105Ah (£449) DC-DC Charger: Victron Orion 12/12-18 (£157) Solar: 200W panels (£180) + Victron MPPT 75/15 (£85) Mains Charger: CTEK MXS 5.0 (£72) Inverter: 600W pure sine (Giandel, £95) Distribution: 12-way fuse box (£60), cable (£85), fuses/terminals (£45) Outputs: Lights, sockets, USB (£80) Battery Monitor: Victron BMV-712 (£185)

Total: £1,493

This gives you:

  • 105Ah usable (2-3 days autonomy)
  • Fast charging from alternator
  • Solar for summer independence
  • Mains charging for campsites
  • Inverter for laptop/phone charging
  • Monitoring to know exactly what’s happening

Perfect for 50-150 nights/year use. Comfortable power for working remotely. Indefinite off-grid in summer, 2-3 days in winter.

This is exactly what I have. Zero regrets.

Final Thoughts

Your electrical system is the heart of your conversion. Everything else depends on it working properly.

I’ve wasted £920 learning what works. Don’t repeat my mistakes:

  • Don’t buy cheap AGM that’ll die in months
  • Don’t buy oversized inverters you’ll never use
  • Don’t use PWM controllers when MPPT is available
  • Don’t undersize cables or skip fusing
  • Don’t guess at battery sizing – calculate properly

Lithium costs more upfront but it’s genuinely cheaper long-term and performs massively better. DC-DC charging is worth every penny over split charge relays. MPPT solar controllers extract 30-40% more power than PWM. Battery monitors tell you what’s actually happening.

The system I have now – £1,493 total – has been flawless for 18 months. Powers everything I need. Charges fast. Lasts for days. Works in Scottish winter and Spanish summer.

If I built van #5 tomorrow, I’d buy exactly the same components. That’s how I know I finally got it right.

Now stop reading, calculate your actual power needs, and build a system that’ll actually work. Your future self will thank you when you’re sitting in a cozy lit van with a charged laptop while everyone else is running out of power.

Continue Reading
By
Van Conversion

Essential Tools And Materials For Campervan Conversions

No Comments
Tools & Materials for DIY Conversions

I’ve built four campervans with tools ranging from a few quid to several hundred. I’m lucky enough to have most tools I’d ever need, but for those of you that are new to van conversions, hopefully this guide on Essential Tools And Materials For Campervan Conversions will give you a good starting point.

After 30 years as a maintenance manager, you’d think I’d know how to do it all. And for building maintenance, I do. But van conversions are different. The tools you need, the materials that work, and the techniques that matter are specific to working in a cramped metal box with curves, ribs, and awkward angles.

This guide is everything I’ve learned about tools and materials across four builds. Not what the marketing says you need. Not what professional converters use (they have different priorities). What you actually need for a DIY conversion that’ll work properly and last.

The Honest Cost Reality

Let me start with the uncomfortable truth: tools cost money. Good tools cost more money. And you need more tools than you think.

But here’s the thing: those tools have also built two garden sheds, countless furniture pieces, home repairs, and helped three mates with their conversions. Cost per project is actually reasonable.

If you’re building one van and starting from scratch:

  • Minimum viable toolkit: £280-£400
  • Comfortable toolkit: £600-£850
  • Professional-grade toolkit: £1,200-£1,800

You can reduce this by borrowing, buying second-hand, or choosing budget brands strategically. I’ll tell you where to save and where not to.

Power Tools: What You Actually Need

I’m going to be brutally honest about each tool. Some you need. Some are nice to have. Some are complete wastes of money for van building.

Cordless Drill/Driver (ABSOLUTELY ESSENTIAL)

What it does: Drilling holes, driving screws, mixing paint/adhesive

Why you need it: You’ll use this constantly. Hundreds of screws. Dozens of holes. Every single day of the build.

Budget option (£45-£80):

  • Ryobi ONE+ 18V
  • Bosch Universal 18V
  • Worx 20V

These will do the job. Just. The batteries don’t last long. The chuck can be wobbly. But for one van build, they’re adequate.

My recommendation (£100-£180):

  • Makita DHP485 18V (£125 for tool + 2 batteries + charger)
  • DeWalt DCD796 18V (£140 for kit)
  • Milwaukee M18 (£155 for kit)

Why spend more? Battery life (you’re not stopping every 20 minutes). Power (actually drills through metal easily). Reliability (doesn’t strip screws or slip). Warranty (they’ll actually honor it).

Premium option (£200-£350):

  • Festool
  • Hilti
  • Milwaukee M18 Fuel

Unless you’re a professional or doing multiple conversions, don’t bother. Diminishing returns.

What I use: Makita DHP485. Had it 8 years. Built four vans, two sheds, countless projects. One battery replacement (£45). Zero regrets. Would buy again tomorrow.

Verdict: Buy Makita, DeWalt, or Milwaukee. 18V system. Get the kit with two batteries and charger. Budget £120-£180.

Impact Driver (HIGHLY RECOMMENDED)

What it does: Drives screws (much better than a drill/driver)

Why you need it: Seriously, once you use an impact driver for screws, you’ll wonder how you lived without it. No cam-out. No stripped heads. Just drives screws perfectly every time.

Do you NEED it? Technically no. Practically yes.

Budget option (£50-£90):

  • Ryobi ONE+ 18V Impact Driver
  • Same battery system as your drill (this matters)

My recommendation (£95-£150):

  • Makita DTD154 (£95 bare tool, or £145 with battery/charger)
  • DeWalt DCF887 (£110 bare)
  • Milwaukee M18 (£120 bare)

Buy “bare tool” if you already have batteries from your drill. Buy the kit if this is your first 18V tool.

What I use: Makita DTD154. Hundreds of screws driven perfectly. Still going strong after 6 years.

Verdict: Buy if budget allows (£95-£150). You’ll thank me when you’re driving your 500th screw and it’s still easy.

Jigsaw (ESSENTIAL)

What it does: Cuts curves, cuts holes (windows, vents, sinks), cuts worktops to size

Why you need it: You’ll cut dozens of curved pieces. Hundreds of cuts total. Can’t do this with any other tool safely.

Budget option (£30-£60):

  • Ryobi 18V cordless (£55)
  • Bosch PST 700 E corded (£45)
  • Erbauer corded (£35 from Screwfix)

These cut. That’s about all I can say. They vibrate a lot. The blade wobbles. Cuts aren’t perfectly square. But they work.

My recommendation (£80-£140):

  • Bosch PST 18 LI cordless (£110)
  • Makita DJV182 cordless (£125)
  • DeWalt DCS334 cordless (£95)

Better blade guidance. Less vibration. Cuts stay square. Variable speed (crucial for different materials). Orbital action (faster cuts in wood).

Premium option (£150-£300):

  • Festool PSC 420
  • Bosch GST 18V-LI

Only worth it if you’re doing lots of fine woodwork. Overkill for van building.

Blade advice: Buy good blades separately. The blades that come with jigsaws are rubbish. I use:

  • Bosch T244D (fast cuts in wood, £8 for pack of 5)
  • Bosch T118B (metal cutting, £12 for pack of 5)
  • Bosch T101B (clean cuts in ply, £7 for pack of 5)

You’ll go through 15-20 blades in a build. Budget £40-£60 for blades.

Verdict: Buy a £80-£140 jigsaw with good blade guidance. Buy decent blades separately. Don’t cheap out here.

Circular Saw (USEFUL BUT NOT ESSENTIAL)

What it does: Cuts straight lines in sheet materials (ply, worktops)

Why you might need it: Faster than a jigsaw for long straight cuts. More accurate for sheet material.

Why you might not: You can do everything with a jigsaw (just slower).

Van #2: Bought a Makita DSS611 cordless circular saw (£120). Massively faster for cutting ply sheets. Much more accurate.

Budget option (£50-£85):

  • Ryobi 18V cordless (£75)
  • Evolution corded (£55)
  • Erbauer corded (£50)

My recommendation (£100-£160):

  • Makita DSS611 18V (£120)
  • DeWalt DCS391 18V (£135)
  • Milwaukee M18 (£145)

What I use: Makita DSS611. Cuts ply and worktops beautifully. Battery lasts ages. No regrets.

Verdict: Nice to have if budget allows. Not essential if you have a good jigsaw and patience. Buy if you’re cutting lots of sheet material.

Orbital Sander (ESSENTIAL)

What it does: Smooths wood, removes paint, prepares surfaces

Why you need it: You can’t build furniture without sanding. You could sand by hand but your arm will fall off.

Budget option (£25-£45):

  • Ryobi 18V cordless (£40)
  • Black & Decker corded (£28)
  • Erbauer corded (£25)

These work. They’re loud and vibrate a lot. But they sand.

My recommendation (£50-£95):

  • Makita DBO180 18V cordless (£75)
  • Bosch PSM 200 AES corded (£65)
  • DeWalt DCW210 18V cordless (£85)

Less vibration = less fatigue. Better dust collection = healthier lungs. Faster sanding.

What I use: Makita DBO180. Sanded all the furniture in all four vans. Still going. Brilliant tool.

Sandpaper: Buy variety packs (40, 80, 120, 240 grit). You’ll use 30-50 sheets in a build. Budget £25-£35.

Verdict: Essential. Budget £50-£95. Get cordless if you’re on the 18V battery platform already.

Angle Grinder (ONLY IF YOU HAVE METAL WORK)

What it does: Cuts metal, grinds welds, removes rust

Why you might need it: If you have welded shelving or rust to remove.

Why you might not: If your van is clean and you’re not cutting metal, skip it.

I needed it in van #1 (ex-fleet van with welded metal shelving). Didn’t need it in vans #2-4.

Budget option (£25-£45):

  • Erbauer 115mm corded (£28)
  • Evolution 115mm cordless (£40)

My recommendation (£50-£95):

  • Makita DGA504 18V cordless (£90)
  • DeWalt DCG405 18V cordless (£85)

What I use: Makita DGA504. Used it extensively in van #1, barely in others. Still works perfectly.

Safety: This is the most dangerous tool in the list. Face shield, gloves, long sleeves mandatory. No exceptions.

Verdict: Only buy if you know you need it. Rent it for a day (£15-£25) if you just need to remove some brackets.

Multi-Tool / Oscillating Tool (USEFUL FOR AWKWARD CUTS)

What it does: Cuts in tight spaces, plunge cuts, detail work

Why it’s useful: Getting into corners. Cutting around ribs. Trimming installed pieces.

Do you need it? Probably not for your first van. Useful but not essential.

Budget option (£30-£60):

  • Ryobi 18V cordless (£55)
  • Erbauer corded (£35)

My recommendation (£70-£130):

  • Makita DTM51 18V cordless (£95)
  • Bosch PMF 250 CES (£85)

What I use: Makita DTM51. Brilliant for awkward cuts. Worth having if you’re doing multiple builds.

Verdict: Skip it for your first build unless you spot a specific need. Add it later if you build another van.

What You DON’T Need (Despite What YouTube Says)

Router: Unless you’re making fancy edge profiles, you don’t need this.

Table saw: Way too big for van building. Circular saw or jigsaw does everything you need.

Planer: You’re buying planed timber. You don’t need to plane it again.

Biscuit joiner: Nice for furniture making. Overkill for van builds. Screws and glue work fine.

Nailer: Tried using a pin nailer in van #3. Pins didn’t hold in ply properly near edges. Went back to screws.

Welder: Unless you’re building a custom metal frame, you don’t need to weld anything.

Hand Tools: The Unsexy Essentials

Power tools get the glory. Hand tools do the actual work.

Measuring and Marking (CRITICAL – DON’T SKIP THESE)

Tape measure (£5-£15): Get a good 5m tape (Stanley FatMax, £12). Not the £2.99 ones that break after a week.

Actually buy two. You’ll lose one. I guarantee it.

Laser measure (£25-£85): Not essential but brilliant for measuring long distances and heights. I use a Bosch GLM 30 (£45). Paid for itself in time saved.

Spirit level (£8-£25): Get a decent 60cm level. Vans aren’t level. Furniture must be. I use a Stanley FatMax (£15).

Combination square (£8-£25): For marking 90-degree angles and checking squareness. Essential for furniture. Bahco 400mm (£18) is excellent.

Marking pencils (£3): Buy proper carpenter’s pencils. Buy 10. You’ll lose them all.

Chalk line (£6): For marking long straight lines. Stanley (£6). Simple and useful.

Cutting and Shaping

Handsaw (£12-£28): Even with power saws, you need a handsaw. Stanley FatMax (£15) is fine.

Hacksaw (£8-£18): For cutting metal (battery terminals, brackets, conduit). Bahco 319 (£12).

Files (£15-£30): Set of metal files for cleaning up cuts and deburring. Draper 200mm set (£18).

Craft knife (£3-£8): Stanley FatMax (£5). Buy 100 spare blades (£8). You’ll go through loads.

Rasp or Surform (£8-£18): For shaping wood quickly. Stanley Surform (£12).

Fixing and Fastening

Screwdrivers (£15-£45): Despite having an impact driver, you need hand screwdrivers. Tight spaces. Delicate work.

Wera or Bahco sets (£25-£35 for good set). Get:

  • Phillips: PH1, PH2, PH3
  • Flathead: 3mm, 5mm, 8mm
  • Pozidrive: PZ1, PZ2, PZ3

Socket set (£25-£80): 3/8″ drive socket set (Halfords Advanced, £45). You’ll use this for bolts, nuts, removing van panels.

Adjustable spanner set (£15-£35): Bahco 9031 set (£28). Two adjustable spanners (150mm and 250mm).

Pliers set (£20-£45):

  • Combination pliers (Knipex, £18)
  • Long nose pliers (£10)
  • Side cutters (£12)

Hex key set (£8-£18): Metric and imperial. Wera or Bondhus (£15). Furniture and van panels use hex bolts.

Clamps (ESSENTIAL – BUY MORE THAN YOU THINK):

G-clamps (£4-£8 each): Buy at least 6. I use 8. Quick-grip clamps (£8-£15 each): Buy at least 4. I use 6.

You can never have enough clamps. Gluing, holding pieces while you screw, keeping things square while the glue dries.

Budget £60-£90 for clamps.

Electrical Work Tools

Wire strippers/crimpers (£15-£45): Essential for 12V work. Automatic wire strippers (£18) are brilliant. Ratchet crimpers (£25) make proper crimps.

Multimeter (£15-£45): You MUST have this for electrical work. Testing voltage, continuity, finding faults.

Budget option: Erbauer (£15). Works. Better option: Fluke 115 (£145). Overkill but brilliant. My recommendation: UNI-T UT33D (£22). Accurate, reliable, cheap enough not to cry if you break it.

Wire cutters (£8-£18): Specifically for cable. Side cutters (£12).

Cable strippers (£12-£25): Automatic (£18). So much faster than a knife.

Plumbing Tools

Adjustable wrench (£8-£18): For tightening fittings. Bahco 8″ (£12).

Pipe cutter (£8-£18): For cutting plastic pipe cleanly. Rothenberger (£12).

Hole saw set (£25-£55): For drilling large holes (sink, vents, cables). Erbauer set (£28).

Step drill bit (£12-£28): For drilling clean holes in metal. Erbauer (£18).

Other Essential Hand Tools

Hammers:

  • Claw hammer (Stanley, £12)
  • Rubber mallet (£8) – for persuading things without damaging them

Pry bar (£8-£18): For removing panels and lifting things. Stanley Wonder Bar (£12).

Utility knife (£5-£12): Heavy-duty (Stanley, £8). Better than craft knife for insulation and thick materials.

Chisel set (£20-£45): For cleaning out corners and adjusting mortises. Bahco 424P set (£28).

Staple gun (£12-£35): For attaching vapor barrier and fabric. Arrow T50 (£22).

Safety Equipment (NOT OPTIONAL)

I’ve been a maintenance manager for 30 years. I’ve seen what happens when people skip safety gear. Don’t be an idiot.

Essential safety gear:

Safety glasses (£3-£12): Buy comfortable ones (£8) or you won’t wear them. Must be impact-rated (EN166).

I use Bolle Safety (£9). Comfortable enough to wear all day.

Dust masks (£8-£25): FFP2 or FFP3 for cutting MDF and sanding. Box of 20 (£15).

Proper mask with replaceable filters (3M 6200, £22 + £15 for filters) if you’re doing lots of work.

Work gloves (£4-£12 per pair): Buy multiple pairs. They get destroyed.

  • Light work: Maxiflex (£5/pair)
  • Heavy work: Mechanix (£18/pair)
  • Cut protection: Aldi special (£4/pair, surprisingly good)

Ear protection (£8-£25): Sanding, grinding, cutting. All loud. You need ear protection.

3M Peltor (£15) – comfortable for all-day wear.

Knee pads (£12-£35): You’ll spend hours on your knees. My knees aren’t great. I use Snickers Craftsmen knee pads (£25). Worth every penny.

Work boots (£40-£85): Steel toe cap. Slip-resistant. I use DeWalt Apprentice (£55). Comfortable and protective.

First aid kit (£15-£35): Plasters, bandages, antiseptic. You will cut yourself. Multiple times.

Fire extinguisher (£20-£35): Keep one near your work area. Especially when working with electrics or gas.

Total safety gear budget: £140-£220

Don’t skip this. Your health is worth more than the saving.

Materials: What You’ll Actually Use

Tools are one thing. Materials are where you’ll spend serious money.

Timber and Sheet Materials

Plywood:

12mm ply (structural): For furniture frames, bed base, subfloors. £25-£35 per 2400mm x 1200mm sheet.

Hardwood ply (birch) is better but expensive (£45-£65/sheet). Softwood ply is fine for most uses.

Budget 6-8 sheets for medium van = £150-£280.

6mm ply (cladding): For wall lining, cupboard panels, doors. £15-£25 per sheet.

Budget 4-6 sheets = £60-£150.

18mm ply (heavy duty): For worktops, bed base if you want extra strength. £30-£45 per sheet.

Budget 1-2 sheets = £30-£90.

What I learned: Van #1: Bought cheapest ply (£18/sheet). It delaminated after 6 months. Had to replace some panels. False economy.

Van #2+: Bought decent hardwood ply (£32/sheet). Still perfect after years. Worth the extra £14/sheet.

Timber (PAR – Planed All Round):

2×2 (47mm x 47mm): For bed frames, structural elements. £4-£6 per 2.4m length. Budget 15-20 lengths = £60-£120.

2×4 (47mm x 100mm): For heavier structural elements if needed. £7-£10 per 2.4m length. Budget 5-8 lengths = £35-£80.

Battens (25mm x 50mm): For wall lining, fixing points. £3-£5 per 2.4m length. Budget 12-15 lengths = £36-£75.

Buy treated timber if possible (extra £1-£2/length). Worth it for moisture resistance.

Worktop:

Kitchen worktop offcut: Solid beech or oak, 28mm thick. Most builders’ merchants have offcut bins. £25-£50 for enough for a van kitchen.

I’ve used beech worktop (£38 for 900mm x 600mm from B&Q) in all four vans. Looks great, durable, easy to work with.

Insulation Materials

Covered in detail in the insulation guide, but budget:

Celotex/Kingspan PIR boards:

  • 50mm (roof): £165-£210 (8 sheets)
  • 25mm (walls/floor): £95-£145 (6-9 sheets)

Expanding foam:

  • Soudal Gap Filler: £6-£8 per can
  • Budget 5-7 cans = £30-£56

Vapor barrier:

  • Reflectix or bubble foil: £40-£60 for roll

Total insulation: £330-£470

Fixings and Fasteners

You’ll use thousands of screws. Literally thousands.

Wood screws: Buy variety packs. You’ll use:

  • 3.5mm x 30mm (general use) – 500 pack (£8)
  • 4mm x 40mm (furniture) – 200 pack (£6)
  • 4mm x 50mm (structural) – 200 pack (£7)
  • 5mm x 60mm (heavy duty) – 100 pack (£6)

Budget £40-£60 for screws.

Self-tapping screws: For fixing into van metal. 4.2mm x 13mm – 200 pack (£8).

Coach bolts: For removable furniture sections. M6 or M8, various lengths. Budget £15-£25.

L-brackets and corner braces: For reinforcing furniture. Various sizes, £1-£3 each. Budget £25-£40 for 15-20 brackets.

Hinges: For cupboard doors. £2-£5 per pair. Budget £20-£35 for 8-10 pairs.

Magnetic catches: For keeping cupboard doors closed. £1-£2 each. Budget £10-£15 for 8-10 catches.

Total fixings: £115-£180

Adhesives and Sealants

PVA wood glue: For furniture joints. Evo-Stik or Gorilla (£8-£12 for large bottle). Budget 2 bottles = £16-£24.

Construction adhesive: For fixing battens and heavy elements. Evo-Stik Serious Stuff or Gorilla Grab (£4-£6 per tube). Budget 4-6 tubes = £16-£36.

Sikaflex 512: For sealing windows and roof vents. £12-£18 per tube (expensive but essential). Budget 2-3 tubes = £24-£54.

Expanding foam: Already mentioned but you’ll use loads.

Silicone sealant: For sinks, worktops, waterproofing. £3-£5 per tube. Budget 3-4 tubes = £9-£20.

Total adhesives: £65-£130

Finishing Materials

Paint:

Primer: For bare wood and metal. £12-£18 per litre. Budget 1L = £12-£18.

Interior paint: Water-based for walls and ceiling. £15-£25 per 2.5L. Budget 2.5L = £15-£25 (white ceiling, grey walls can share).

Varnish/oil: For worktops and exposed wood. Danish oil (£12 per litre) or hard wax oil (£18 per litre). Budget 0.5L = £6-£9.

Total paint: £33-£52

Flooring:

Vinyl click-lock: Waterproof, durable. £25-£35 per pack (covers 2-2.5 square meters). Budget 5-6 packs = £125-£210.

Edge beading: Plastic trim for edges. £8-£15 per length. Budget £15-£25 total.

Total flooring: £140-£235

Electrical Materials

This is extensive. Covered in detail in electrical guide but budget:

Cable:

  • Various sizes (1.5mm² to 10mm²)
  • Budget £80-£120

Fuse box and fuses: £40-£80

Lights, sockets, switches: £60-£100

Connectors and terminals: £30-£50

Total electrical materials: £210-£350 (not including battery, solar, etc.)

Plumbing Materials

Sink: £35-£80 Tap: £20-£45 Pump: £55-£85 Hose and fittings: £20-£35 Water containers: £35-£60 Waste container: £15-£25

Total plumbing: £180-£330

What To Buy New vs. Used vs. Borrow

After four builds, here’s my strategy:

Always Buy New

Safety equipment: Never compromise. New safety glasses, new gloves, new masks.

Electrical components: Don’t mess with used batteries or electrics. Too risky.

Cutting blades: Cheap and you need sharp ones.

Fasteners and fixings: Not worth buying used. Too fiddly.

Buy Used If Good Condition

Power tools: eBay, Gumtree, Facebook Marketplace are goldmines.

I bought my Makita circular saw used (£75, saved £45). Works perfectly. Check it runs, check battery condition, check blade adjustment.

Hand tools: Spanners, sockets, hammers don’t wear out. Buy used.

Clamps: Quality clamps last forever. Buy used Record or Bessey clamps for half price.

Consider Borrowing

Specialist tools you’ll use once:

  • Hole saw set (if a mate has one)
  • Angle grinder (if you only need it one day)
  • Laser level (nice to have but not essential)

Where I went wrong:

Van #1: Bought an oscillating multi-tool (£45) for one job. Used it once. Waste of money. Should have borrowed or skipped it.

Van #2: Borrowed a friend’s router for edge details. Used it, returned it. Perfect. Didn’t need to own one.

Consider Renting

For single-use or specialist tools:

Hire shops (HSS, Brandon, Jewson) rent tools daily/weekly.

Good candidates for renting:

  • Angle grinder: £15-£25/day
  • Large compressor: £25-£40/day
  • Pressure washer: £20-£30/day
  • Scaffold tower: £30-£50/week

When it makes sense:

If you need it for one day and buying it would cost £50+, renting for £20-£30 makes sense.

Where To Actually Buy (UK Specific)

After buying tools and materials for four vans, here’s where I go:

Power Tools

Screwfix: Best prices on Ryobi and DeWalt. Trade card gets 10% off. Good stock.

Toolstation: Similar to Screwfix. Sometimes cheaper, sometimes not. Compare prices.

Makita Power Tools Direct: Online. Often have deals. Where I bought most of my Makita kit.

Machine Mart: Good for specialized tools. Occasional brilliant sales.

Amazon: Price compare. Sometimes great deals. Sometimes more expensive. Read reviews carefully.

Used tools:

  • Facebook Marketplace (best for local collection)
  • eBay (wider selection but watch postage costs)
  • Gumtree (hit and miss)

Timber and Sheet Materials

Wickes: Decent quality ply. Often have 20% off sales. Will cut sheets for free (ask nicely).

B&Q: More expensive but wider range. Good for worktop offcuts.

Selco: Trade-focused. Need trade card but worth getting (free). Cheaper than Wickes/B&Q for bulk.

Travis Perkins: Good quality, trade prices (need account). My go-to for bulk timber.

Local timber merchants: Often cheaper than big chains. Google “timber merchant near me”. Build a relationship and prices drop.

Insulation

Screwfix: Celotex/Kingspan, reasonable prices Wickes: Often on sale Travis Perkins: Good trade prices Insulation Superstore: Online, competitive, delivery included

Fixings and Fasteners

Screwfix: Excellent range, trade card discount Toolstation: Similar to Screwfix Screw Station: Online, brilliant range, good bulk prices Amazon: For specialty fixings

Electrical

12V Planet: Specialist van electrics, brilliant knowledge Amazon: General electrical components Screwfix: Cable and basic components CampervanHQ: Van-specific electrical bits

Plumbing

Screwfix: Everything you need Toolstation: Alternative B&Q: Sinks and taps (good range)

Flooring

Wickes: Good vinyl range B&Q: Wider selection, more expensive Flooring Hut: Online, competitive prices Tile Mountain: Great prices on vinyl

The Three Budget Levels: Complete Toolkit

Let me give you three realistic scenarios for tool purchases.

Budget 1: Minimum Viable Toolkit (£340-£480)

For: First van, tight budget, willing to borrow some tools

Power tools:

  • Ryobi drill/driver 18V kit: £65
  • Ryobi impact driver (bare): £50
  • Bosch jigsaw (corded): £45
  • Makita orbital sander (cordless): £75

Hand tools:

  • Tape measures (2): £12
  • Spirit level: £10
  • Combination square: £12
  • Screwdriver set: £20
  • Socket set: £30
  • Adjustable wrenches (2): £18
  • Pliers set: £25
  • Hex keys: £10
  • Clamps (6): £40

Electrical:

  • Wire strippers/crimpers: £18
  • Multimeter: £15

Safety:

  • Safety glasses: £6
  • Dust masks (box): £12
  • Gloves (3 pairs): £15
  • Knee pads: £15

Total: £483

What you’re compromising: Some cheaper tools, no circular saw, borrowing specialized tools

Will this work? Yes. It’s tight but adequate for one build.

Budget 2: Comfortable Toolkit (£700-£950)

For: Serious build, plan to use tools again, want quality that lasts

Power tools:

  • Makita drill/driver 18V kit: £125
  • Makita impact driver (bare): £95
  • Makita jigsaw (cordless bare): £125
  • Makita circular saw (cordless bare): £120
  • Makita orbital sander (cordless bare): £75

Hand tools:

  • Tape measures (2): £15
  • Laser measure: £45
  • Spirit level: £15
  • Combination square: £18
  • Screwdriver set (Wera): £35
  • Socket set (Halfords): £45
  • Adjustable wrenches: £28
  • Pliers set (Knipex): £40
  • Hex keys: £15
  • Clamps (10): £75

Electrical:

  • Wire strippers/crimpers (good): £25
  • Multimeter (UNI-T): £22

Cutting tools:

  • Handsaw: £15
  • Hacksaw: £12
  • Files set: £18
  • Craft knife + blades: £12

Safety:

  • Safety glasses (2 pairs): £12
  • Dust masks (better): £18
  • Gloves (5 pairs): £25
  • Knee pads (good): £25
  • Work boots: £55
  • Ear protection: £15

Total: £1,090

What you’re getting: Quality tools that last, complete set, comfortable to use

Will this work? Brilliantly. This is what I’d buy if starting fresh.

Budget 3: Professional-Grade Toolkit (£1,400-£1,900)

For: Multiple builds, want best quality, long-term investment

Power tools:

  • Makita drill/driver 18V kit: £125
  • Makita impact driver (bare): £95
  • Makita jigsaw (cordless bare): £125
  • Makita circular saw (cordless bare): £120
  • Makita orbital sander (cordless bare): £75
  • Makita angle grinder (cordless bare): £90
  • Makita multi-tool (cordless bare): £95
  • Extra batteries (2 x 5.0Ah): £120

Hand tools:

  • Tape measures (3): £18
  • Laser measure (Bosch): £45
  • Spirit levels (2 sizes): £30
  • Combination square: £18
  • Screwdriver set (Wera): £35
  • Socket set (Halfords Advanced): £75
  • Adjustable wrenches (Bahco): £35
  • Pliers set (Knipex): £50
  • Hex keys (Wera): £25
  • Clamps (15): £110
  • Files set: £25
  • Chisels set (Bahco): £28

Electrical:

  • Wire strippers (automatic): £25
  • Ratchet crimpers: £35
  • Multimeter (Fluke): £145

Specialist:

  • Hole saw set: £45
  • Step drills: £25

Safety:

  • Safety glasses (3 pairs): £18
  • Dust masks (3M 6200 + filters): £37
  • Gloves (8 pairs): £40
  • Knee pads (Snickers): £25
  • Work boots (DeWalt): £55
  • Ear protection: £15
  • First aid kit: £25

Total: £1,673

What you’re getting: Professional quality, complete set, multiple van builds, comfortable, reliable

Will this work? This is overkill for one van but perfect for serious DIY or multiple builds.

Complete Materials Budget by Van Size

Here’s realistic material costs for different van sizes:

Small Van (SWB – VW Transporter size)

Insulation: £250-£350 Timber/ply: £180-£280 Fixings: £80-£120 Adhesives: £50-£80 Flooring: £90-£140 Paint/finish: £30-£50 Electrical materials: £180-£300 Plumbing materials: £150-£280

Total materials: £1,010-£1,600

Medium Van (MWB – Transit Custom size)

Insulation: £380-£550 Timber/ply: £280-£420 Fixings: £115-£180 Adhesives: £65-£130 Flooring: £140-£235 Paint/finish: £40-£65 Electrical materials: £210-£350 Plumbing materials: £180-£330

Total materials: £1,410-£2,260

Large Van (LWB – Sprinter size)

Insulation: £550-£800 Timber/ply: £420-£650 Fixings: £150-£240 Adhesives: £85-£160 Flooring: £200-£320 Paint/finish: £50-£80 Electrical materials: £240-£400 Plumbing materials: £200-£380

Total materials: £1,895-£3,030

These are realistic materials-only costs. Add your labor (free) and tools (already covered above).

Common Tool/Material Mistakes

Mistake 1: Buying Everything At Once

What I did: Van #1, bought £400 worth of materials before starting. Halfway through, needed different materials. Ended up with unused stuff.

Better approach: Buy materials for each phase as you get there. You’ll adjust plans based on what you learn.

Exception: Buy all insulation at once (prices fluctuate, and you want consistent batches).

Mistake 2: Cheap Blades/Bits

What I did: Bought budget jigsaw blades (£3 for pack of 5). They went blunt after 3 cuts. Needed 20 blades instead of 10.

Cost: £12 for rubbish blades vs. £24 for good blades that last.

Lesson: Blades and drill bits are consumables. Buy decent ones. Bosch, Makita, DeWalt. They last 3-4x longer.

Mistake 3: Wrong Timber Sizes

What I did: Van #2, bought 3×3 timber (70mm x 70mm) thinking bigger = stronger. It was overkill, heavy, and wasted space.

Lesson: 2×2 (47mm x 47mm) is adequate for 95% of van furniture. Only go bigger if you have a specific structural need.

Mistake 4: Not Enough Sandpaper

What I did: Bought one variety pack of sandpaper (£12, 20 sheets). Ran out halfway through sanding. Had to stop work to buy more.

Lesson: Buy two packs. You’ll use it all. Having to stop mid-sanding is frustrating.

Mistake 5: Assuming Materials Match Specs

What I did: Measured a space as 400mm wide. Bought 400mm wide ply. It didn’t fit (van ribs aren’t parallel).

Lesson: Buy oversized and trim to fit. Add 10% to all material measurements. You can cut off. You can’t add on.

Mistake 6: Forgetting About Waste

What I did: Calculated I needed 6 sheets of ply exactly. I needed 7.5 sheets because of wastage from cuts.

Lesson: Add 25% for wastage on sheet materials. 15% on timber. Better to have leftovers than run out.

Mistake 7: Cheap Fixings

What I did: Bought budget screws (£15 for massive box). Half of them stripped or snapped. Drove me mental.

Lesson: Buy decent screws. Spax, Timco, Reisser. They cost 20% more but work properly. Worth it for sanity.

Tool Maintenance (Make Your Investment Last)

Clean tools after use:

  • Wipe down power tools (remove dust and debris)
  • Clean blades and bits (prevents rust)
  • Oil moving parts occasionally

Store properly:

  • Keep power tools in cases (protects them)
  • Hang hand tools (prevents damage)
  • Keep dry (rust is the enemy)

Charge batteries correctly:

  • Don’t leave on charger permanently
  • Store at 40-60% charge if not using for months
  • Run them occasionally (every 2-3 months if stored)

Sharpen/replace consumables:

  • Sharpen chisels and plane blades
  • Replace dull saw blades (they’re dangerous)
  • Replace worn drill bits

Check fixings regularly:

  • Tighten loose screws on power tools
  • Replace cracked or damaged handles
  • Check electrical cables for damage

Tools I’ve had to replace:

  • Jigsaw (burnt out the £15 one, replaced with £110 one that’s lasted 6 years)
  • Batteries (lithium batteries last 3-5 years typically)
  • Measuring tape (lost both original ones, wear and tear on the third)

Tools still going strong from 2018:

  • Makita impact driver (thousands of screws, still perfect)
  • Socket set (metal doesn’t wear out)
  • Spirit level (basic but works)
  • Most hand tools (spanners, screwdrivers, pliers)

Final Recommendations: What I’d Buy Today

If I was starting fresh today with zero tools, here’s exactly what I’d buy:

Power tool system: Makita 18V (best balance of cost, quality, range)

Initial purchase (£540):

  • DHP485 Drill/driver kit (2 batteries + charger): £125
  • DTD154 Impact driver (bare): £95
  • DJV182 Jigsaw (bare): £125
  • DSS611 Circular saw (bare): £120
  • DBO180 Orbital sander (bare): £75

Hand tools (£380):

  • Measuring and marking: £80
  • Cutting tools: £45
  • Spanners and sockets: £90
  • Screwdrivers and hex keys: £55
  • Clamps: £75
  • Electrical tools: £35

Safety gear (£165):

  • Complete safety setup as per Budget 2 above

Total toolkit: £1,085

This would handle 95% of van conversion tasks comfortably.

For materials, budget:

  • MWB van: £1,800-£2,500 (materials only)
  • Tools: £1,085
  • Total first-van cost: £2,885-£3,585 (plus the actual van)

Add 20% contingency: £3,462-£4,302

Final Thoughts

Tools and materials are the foundation of your build. You can have perfect plans, brilliant skills, and loads of time, but with wrong tools or rubbish materials, you’ll build rubbish.

I’ve learned this expensively. £480 on tools I didn’t need. £350 on cheap materials that failed. £200 on fixings that stripped or snapped. That’s over £1,000 wasted.

But I’ve also learned where quality matters and where budget is fine:

Don’t cheap out on:

  • Power tools you’ll use constantly (drill, impact driver, jigsaw)
  • Safety equipment (never)
  • Structural timber and ply
  • Electrical components
  • Cutting blades and drill bits

Budget options are fine for:

  • Hand tools that don’t wear out (spanners, hammers)
  • Consumables you’ll replace anyway
  • Single-use items
  • Measuring tools (tape measure doesn’t need to be fancy)

The toolkit I have now – accumulated over many years – has built four vans, two sheds, countless furniture pieces, and done all my home maintenance. Cost per project is actually very reasonable.

If you think about tools as an investment rather than an expense, suddenly spending £1,000 on a good toolkit makes sense. Especially if you’ll use it for years.

Start with the basics. Buy quality where it matters. Add tools as you need them. Maintain what you have.

And for the love of everything, buy decent jigsaw blades. Trust me on this.

Now stop reading and go buy tools. Your van conversion is waiting.

Continue Reading
By
Van Conversion

Designing the Perfect Campervan Layout

No Comments
Designing the Perfect Campervan Layout

I’ve built four campervans. The first layout was so bad I couldn’t actually cook standing up. The second looked beautiful in photos but was completely impractical for real life. The third was better but I still couldn’t fit bikes inside without removing the bed. The fourth? Finally got it mostly right. This journey has taught me the importance of a Perfect Campervan Layout.

Between those four builds, I’ve redesigned layouts completely three times, made £850 worth of furniture I had to scrap and rebuild, and learned that what looks perfect on paper often doesn’t work when you’re trying to cook pasta while your partner is trying to get changed and the dog is trying to exist in the same space.

This guide is everything I wish I’d known before I drew my first layout plan. Not the theory. Not the Instagram-perfect versions. The actual reality of living in a small metal box and how to design a space that works for your real life, not someone else’s aesthetic.

This guide is everything I wish I’d known before I drew my first layout plan. Not the theory. Not the Instagram-perfect versions. The actual reality of living in a small metal box and how to design a space that works for your real life, not someone else’s aesthetic. A good design is the key to achieving the Perfect Campervan Layout.

Why Layout Design Matters More Than Anything Else

Here’s the truth: you can fix bad insulation. You can upgrade your electrical system. You can repaint walls. But a fundamentally bad layout? That requires ripping everything out and starting again.

I know because I’ve done it. Twice.

Van #2: Beautiful L-shaped kitchen, gorgeous overhead storage, lovely dinette area. Completely useless. I couldn’t stand up where I needed to. The dinette ate space we never used. The overhead storage blocked the window. After six months of frustration, I ripped out £650 worth of furniture and rebuilt it.

Van #3: Much better, but I built permanent furniture everywhere. Looked great. Then we got bikes and realized we couldn’t fit them inside without dismantling half the interior. Spent another £200 making furniture modular.

What a good layout does:

  • Lets you actually live comfortably in the space
  • Makes daily tasks easy (cooking, sleeping, changing clothes)
  • Stores everything you actually need
  • Adapts to different trips (weekend vs. month-long)
  • Doesn’t waste space on things you never use
  • Works for YOUR specific needs (not Instagram’s)

What a bad layout does:

  • Forces you into awkward positions constantly
  • Makes simple tasks frustrating
  • Leaves you with nowhere to put essential items
  • Looks great but doesn’t function well
  • Follows someone else’s idea of perfect

Layout design isn’t creative expression. It’s practical problem-solving. The best layout is the one you forget about because everything just works.

Understanding Your Real Constraints

Before you draw a single line, understand what you’re actually working with.

Van Size Reality Check

I’ve worked with different sizes. Here’s the usable space reality:

VW Transporter T5/T6 (SWB)

  • Cargo area: 1.7m long x 1.7m wide x 1.4m high (standard roof)
  • Usable space: About 4 cubic metres
  • Standing height: No (unless you install a pop-top)
  • Reality: Cosy. Very cosy. Works for weekends or one person full-time.

Ford Transit Custom (MWB, medium roof)

  • Cargo area: 2.6m long x 1.7m wide x 1.75m high
  • Usable space: About 7.7 cubic metres
  • Standing height: Yes, if you’re under 1.83m (6ft)
  • Reality: Sweet spot for most people. Enough space without being massive.

Mercedes Sprinter (MWB, high roof)

  • Cargo area: 3.2m long x 1.8m wide x 1.9m high
  • Usable space: About 11 cubic metres
  • Standing height: Yes, properly (2m internal height)
  • Reality: Luxurious amount of space. Pain to park. Overkill for weekends.

Mercedes Sprinter (LWB, high roof)

  • Cargo area: 4.3m long x 1.8m wide x 1.9m high
  • Usable space: About 14.7 cubic metres
  • Standing height: Yes, everywhere
  • Reality: This is a small house. Also won’t fit most UK car parks.

What size do you actually need?

I’ve lived in a SWB Transporter and now have a MWB Transit Custom. Here’s my honest assessment:

Choose SWB if:

  • Weekend trips only (max 1-2 weeks)
  • Solo or couple without pets
  • You prioritize city parking and stealth
  • You’re okay without standing height
  • Budget is tight (smaller = cheaper everything)

Choose MWB if:

  • Regular trips (weeks at a time)
  • Couple with dog, or small family
  • You want standing height
  • You want a real kitchen and storage
  • You’ll use it 30+ nights per year

Choose LWB if:

  • Full-time or near full-time living
  • You want a wet room/toilet
  • You need office space inside
  • You’re okay with parking challenges
  • You have the budget (bigger = more expensive everything)

My recommendation: For most UK-based people doing serious weekends and occasional longer trips, MWB with medium-to-high roof is the sweet spot. Big enough to be comfortable, small enough to be practical.

Understanding Your Actual Usage

Before you design anything, honestly answer these questions:

How will you actually use the van?

  • Weekend trips (2-3 nights)
  • Week-long holidays
  • Extended tours (2-4 weeks)
  • Full-time living
  • Occasional camping (10-20 nights/year)

Be honest. Most people design for full-time living but use it 15 nights a year. That’s wasted space and money.

Who’s using it?

  • Solo
  • Couple
  • Family with kids
  • With pets
  • Friends occasionally

What activities?

  • Beach camping (need outdoor shower, sand management)
  • Mountain adventures (need bike storage, hiking gear space)
  • Festivals (need party supplies, more seating)
  • Work travel (need desk space, good lighting, power)
  • Photography trips (need gear storage, work surface)

What season?

  • Summer only (different needs than winter)
  • Year-round (need serious heating, insulation matters more)
  • Shoulder season mostly (spring/autumn – easier)

I designed van #1 for long weekends. I used it maybe 40 nights that year. All that space for a shower and toilet? Wasted. Van #4 is designed for 80-100 nights per year with occasional longer trips. Much more practical.

Physical Constraints You Can’t Change

Your height matters enormously.

I’m 1.78m (5’10”). My wife is 1.5m (5’9″). We can both stand in a medium roof Transit Custom. Just.

My mate is 1.93m (6’4″). He can’t stand in anything except a high roof. This fundamentally changes layouts – if you can’t stand up, you build differently.

Your mobility matters.

Can you:

  • Climb over furniture to get to the bed?
  • Squat down to access under-bed storage?
  • Reach overhead cupboards?
  • Step up into the van easily?

I’m reasonably fit but my knees aren’t great. I avoid layouts requiring constant climbing over things.

Your sleeping position matters.

  • Side sleeper: Need minimum 1.2m width, prefer 1.4m
  • Back sleeper: Can manage 1.1m width
  • Couple: Need 1.4m minimum, 1.6m is comfortable
  • Restless sleeper: Want space to spread out

Your cooking habits matter.

  • Rarely cook: Tiny kitchen is fine
  • Cook proper meals: Need worktop space, storage for ingredients
  • Coffee only: Just need a kettle and mug storage
  • Breakfast cook: Need space for multiple pans

Don’t design a massive kitchen if you eat out most of the time. Don’t design a tiny one if you actually cook.

The Essential Zones (And How Much Space They Actually Need)

Every van needs certain functional areas. Here’s the reality of how much space each actually requires.

Zone 1: Sleeping Area (Priority 1)

You spend 8 hours here every night. Get this wrong and everything else is miserable.

Minimum dimensions:

  • Solo: 1.9m x 1.0m (tight but manageable)
  • Comfortable solo: 1.9m x 1.2m
  • Couple minimum: 1.9m x 1.3m (we tried this – too narrow)
  • Couple comfortable: 1.9m x 1.4m
  • Couple luxury: 1.9m x 1.6m
  • With dog/kids: 1.9m x 1.6m minimum

Don’t compromise on length. 1.9m is absolute minimum unless you’re very short. I’m 1.78m and need every bit of 1.9m.

Bed position options:

Across the back (what I use):

  • Pros: Uses full width (1.7m+), easy access, loads of storage underneath, simple to build
  • Cons: Takes up 1.9m of length, limits rear access
  • Best for: MWB and LWB vans where length isn’t critical

Side-to-side along one wall:

  • Pros: Leaves rear open, can fold up for garage space, versatile
  • Cons: Limited width (max 1.2m typically), difficult to make comfortable for couples
  • Best for: Solo travelers, SWB vans, people who need bike storage

Rock and roll bed:

  • Pros: Doubles as seating, quick conversion, saves space during day
  • Cons: Expensive (£1,200-£2,500), uncomfortable compared to proper bed, limits rear door access
  • Best for: Weekend warriors who want day-time seating space

Pull-out/extending bed:

  • Pros: Saves daytime space, can create larger sleeping area
  • Cons: Complex mechanism, stuff must be cleared before sleeping, more things to break
  • Best for: People who use van during day for working/living

Roof pop-top bed:

  • Pros: Doesn’t use floor space, kids love it, adds standing height
  • Cons: Expensive (£2,500-£5,000 installed), cold in winter, can’t use in high winds
  • Best for: Families, people who need maximum floor space

My experience:

Van #1: Rock and roll bed (£1,450)

  • Uncomfortable. Really uncomfortable. The cushions were hard, the frame was uneven, and I couldn’t get a proper mattress on it.
  • Useful as seating but we barely used it as seating.
  • Sold it for £800 and built a fixed bed.

Van #2-4: Fixed bed across the back (1.9m x 1.4m)

  • Cost: £180 in materials
  • Comfortable with a proper 10cm memory foam mattress (£285)
  • Massive storage underneath (split into sections with plastic boxes)
  • Can remove front section (4 bolts) for bike access if needed
  • No regrets. This is what I’d build again.

Bed construction tips:

What worked:

  • 18mm ply base
  • 47mm x 75mm timber frame
  • Slats across the top (18 slats, 50mm spacing)
  • Allows airflow under mattress (prevents moisture)
  • Front section bolted (removable), back section screwed (permanent)

What didn’t work:

  • Solid ply base (no airflow – mattress got damp)
  • Too-narrow slats (sagged under weight)
  • Not securing it properly (moved while driving – terrifying on motorway)

Zone 2: Kitchen (Priority 2)

You need to cook. Even if it’s just heating beans and boiling water for coffee.

Minimum kitchen:

  • Worktop: 60cm x 40cm
  • Hob: Two burner (you don’t need four)
  • Storage: 30L for food and cooking equipment
  • Sink: 30cm diameter (or skip it entirely)

Comfortable kitchen:

  • Worktop: 90cm x 50cm
  • Hob: Two burner gas or single induction
  • Storage: 60L minimum (cupboard + drawer)
  • Sink: 35cm diameter with draining board

Luxury kitchen:

  • Worktop: 120cm x 50cm
  • Hob: Three burner or two-burner + grill
  • Storage: 100L+ (multiple cupboards)
  • Sink: 40cm double bowl
  • Fridge: 40L+ compressor (separate from kitchen but counts)

What you DON’T need:

An oven. I’ve built one (van #2). Used it four times. It heated the van unbearably, used loads of gas, and took up space I needed for storage. Ripped it out after a year.

A four-burner hob. Unless you’re cooking for six people regularly, two burners is plenty. I cook full roast dinners on two burners. Stew in one pan, veg in the other. Easy.

A massive sink. I’ve had everything from a 25cm bowl to a 40cm double-bowl sink. The sweet spot is 30-35cm single bowl. Big enough to wash pans, small enough not to dominate the worktop.

Kitchen layout options:

Side kitchen (galley style):

  • Kitchen units along one side
  • Usually 80-120cm long
  • Worktop, hob, sink in a line
  • Storage underneath

Pros: Efficient workflow, everything in reach, easy to build Cons: Can block one side of van, limits width for other things

L-shaped kitchen:

  • Kitchen along one side and across the back
  • More worktop space
  • Can separate wet (sink) and cooking zones

Pros: Loads of worktop, feels spacious, very functional Cons: Takes up lots of floor space, expensive to build, limits sleeping area

Rear kitchen:

  • Kitchen across the back near doors
  • Access from rear or from inside
  • Popular in panel vans

Pros: Easy loading, can cook outside with doors open, leaves living area clear Cons: Bed must be elsewhere, less convenient in bad weather, security issues with rear doors open

My experience:

Van #1: Tiny side kitchen (60cm long)

  • Worktop: 60cm x 40cm
  • One-burner camping stove
  • No sink (used a washing up bowl)
  • Barely adequate. Constantly running out of space. Everything was cramped.

Van #2: L-shaped kitchen (looked amazing)

  • Worktop: 90cm along side + 80cm across back
  • Two-burner hob + oven
  • 35cm sink with draining board
  • Loads of storage
  • Problem: Took up so much space the bed was cramped. The oven was useless. The L-shape meant I was always in someone’s way.
  • Ripped it out after 6 months.

Van #3-4: Side kitchen (90cm long, optimized)

  • Worktop: 90cm x 50cm
  • Two-burner gas hob
  • 32cm round sink
  • Cupboard underneath + one drawer
  • Perfect. Enough space to cook properly. Not so big it dominates the van. Would build this again.

Kitchen placement relative to other zones:

Think about workflow:

  1. Food storage → 2. Prep area → 3. Cooking → 4. Eating → 5. Washing up

My current layout:

  • Food storage in cupboard below and overhead
  • Prep area on worktop (60cm clear space)
  • Hob at end of worktop
  • Sink next to hob
  • Seating area opposite (eating zone)
  • Washing up in sink, dishes drain on worktop

This flows naturally. I’m not constantly moving around the van.

Fridge placement:

Separate decision but affects kitchen layout.

Options:

  • Under worktop (takes cupboard space)
  • Under seat (takes seating/storage space)
  • Slide-out drawer (expensive but excellent access)
  • Separate location entirely

I have mine under the seating area opposite the kitchen. 20L compressor fridge (Alpicool C20, £185). Easy access, doesn’t block anything, stays cool in its ventilated space.

Zone 3: Storage (Priority 3 – More Critical Than You Think)

I massively underestimated storage in every build. Everyone does.

What you actually need to store:

Clothes:

  • 7 days for two people = two large rucksacks worth
  • Extra jackets, waterproofs (bulky)
  • Spare shoes, boots
  • Hats, gloves, scarves

Food:

  • Dry goods (pasta, rice, tins) = 20-30L
  • Snacks and treats = 10L
  • Herbs, spices, oils = 5L
  • Fresh food in fridge

Cooking equipment:

  • Pans (2-3), pots (1-2), kettle
  • Plates, bowls (4 of each minimum)
  • Mugs (4), glasses (4)
  • Cutlery, utensils, kitchen knife
  • Storage: 25-35L

Outdoor gear:

  • Walking boots, climbing shoes, wetsuits, etc.
  • Camping chairs (2) = bulky
  • Beach stuff or climbing gear or bike tools
  • Storage: 40-60L depending on your hobbies

Bedding:

  • Duvet, pillows
  • Spare blanket
  • Sheets (ideally 2 sets)

Bathroom:

  • Toiletries for two people = surprisingly large
  • Towels (4 minimum)
  • Toilet paper, cleaning supplies

Tools and spares:

  • Basic toolkit
  • Spare fuses, bulbs, electrical bits
  • Duck tape, cable ties, fixings
  • WD-40, spare fluids

Random essential stuff:

  • Dog supplies (food, bowls, leads, bedding)
  • Books, games, entertainment
  • Work equipment (laptops, chargers)
  • Camera gear
  • First aid kit

Total storage needed realistically:

  • Minimum (weekends only): 200-250L
  • Comfortable (regular use): 300-400L
  • Full-time living: 500L+

Storage solutions that work:

Underbed storage:

  • Largest available space usually
  • I use Really Useful Boxes (84L size, £15 each)
  • Three boxes fit under my bed (252L total)
  • Organized: 1. Clothes, 2. Outdoor gear, 3. Tools/spares
  • Access: Remove front bed section (30 seconds)

Overhead cupboards:

  • Above bed, along walls
  • Maximum depth: 35cm (deeper and they’re claustrophobic)
  • Perfect for light items: clothes, bedding, towels
  • My overhead: 1.8m x 0.35m x 0.3m deep = 189L

Kitchen storage:

  • Cupboard under worktop: Food and pans = 60L
  • Drawer: Utensils and small items = 15L
  • Overhead (above kitchen): Plates, mugs, glasses = 25L

Under-seating storage:

  • Bench seat with storage underneath
  • Mine: 0.8m x 0.4m x 0.4m deep = 128L
  • Contains: fridge (20L) + 12V electrical (20L) + misc (88L)

Door pockets and small storage:

  • Over door hooks
  • Mesh pockets
  • Magnetic strips (knives, tools)
  • Tiny spaces add up

Total in my current van: About 680L of actual usable storage. And it’s still not quite enough sometimes.

Storage mistakes I made:

Mistake 1: Beautiful cupboards with no access Van #2 had gorgeous overhead cupboards. Opening required removing everything from the worktop first. Used them twice. Waste of money.

Mistake 2: Deep shelves 40cm deep overhead cupboards. Things disappeared at the back. Impossible to see what you had. Frustrating.

Mistake 3: No organization system Everything just thrown in underbed space. Had to empty everything to find one thing. Maddening.

Mistake 4: Fixed shelves in cupboards Can’t reorganize. Can’t fit different-sized items. Inflexible.

What works better:

  • Shallow overhead cupboards (25-30cm max)
  • Removable shelves or no shelves (use boxes instead)
  • Clear/translucent storage boxes (see what’s inside)
  • Labeled boxes (seems obvious but essential)
  • Easy access to everything you use daily

Zone 4: Seating (Priority 4)

You need somewhere to sit that isn’t your bed.

Minimum: Floor cushions (free if you’re comfortable sitting on floor)

Better: Simple bench seat

  • 80cm x 40cm seating area = 2 people cozy
  • Cushions on top (£40-£80 for foam + fabric)
  • Storage underneath

Comfortable: L-shaped seating or bench + chairs

  • Proper seating for 2-4 people
  • Table for eating/working
  • Relaxing space

What you don’t need: A full dinette setup unless you’ll actually use it.

Van #2 had a dinette. Fold-out table, L-shaped seating, the works. Cost me £380 to build. Used it maybe 15 times in a year. Most of the time we ate outside or sat on the bed. It took up huge amounts of space for minimal benefit.

Ripped it out. Built a simple bench seat instead. Cost £95. Use it constantly.

Current setup:

  • Bench seat: 80cm along one wall, 60cm along back
  • Cushions on top
  • Storage underneath
  • Removable camping table (£35) stored in underbed
  • Works perfectly. Sit here to eat, read, work on laptop
  • When we need more space, the camping table comes out

Seating position relative to other zones:

Seating opposite kitchen = perfect. You can:

  • Cook while chatting to someone sitting
  • Pass food from kitchen to seating easily
  • Use seating as overflow prep space if needed

Seating facing the same direction as travel = illegal for passengers in some cases. Check regulations. Must have proper seatbelts and comply with laws.

Zone 5: Workspace (Optional But Important for Remote Work)

If you’re working remotely, you need dedicated workspace.

Minimum workspace:

  • 50cm x 40cm flat surface
  • Power (12V or 240V)
  • Lighting
  • Somewhere to sit comfortably

Better workspace:

  • 70cm x 50cm surface
  • Laptop + notebook space
  • Multiple power outlets/USB
  • Good natural light
  • Proper seating position (not hunched)

My solution:

I don’t have dedicated workspace. I use:

  • Kitchen worktop (cleared of stuff) = 60cm x 50cm
  • Sitting on bench seat
  • USB charging points nearby
  • LED overhead light
  • Window next to worktop (natural light)

Works for 2-3 hours of laptop work. Not ideal for full days but adequate for emails and admin.

If you work 4+ hours daily in the van: Consider a dedicated desk area. This usually means:

  • Sacrificing some seating or storage space
  • Mounting a fold-down desk
  • Using the dinette table as permanent desk
  • Having a separate office van (some people literally have two vans)

Zone 6: Bathroom/Toilet (Optional – Skip Unless Full-Time)

Reality check: Most people don’t need a toilet or shower in their van.

Toilet: I have a portable Thetford Porta Potti (£68) that lives in a sealed box under the bed. Used it maybe 10 times in two years. But when you need it at 3am in a layby, it’s worth having.

Shower: Nope. Never built one. Never missed it.

Solutions that work better:

  • Campsites (£15-£25 per night gets you hot showers)
  • Gym membership (£25/month, hot showers anywhere)
  • Wild swimming (free, character-building)
  • Solar shower bag (£18) hung from the door in summer
  • Portable camping shower (£25-£45) for rinsing off

If you’re going full-time and absolutely must have a shower:

Budget space:

  • Wet room: 0.8m x 0.8m minimum
  • Shower tray, shower head, curtain
  • Gray water tank (25L minimum)
  • Hot water system (adds complexity and weight)
  • Ventilation (essential – moisture is a nightmare)

This is 0.64 square meters of floor space. In a MWB van (4.25 square meters), that’s 15% of your floor gone. Worth it? Only you can decide.

My mate has a full wet room in his LWB Sprinter. Uses it twice a week. Brilliant. But he lives in it 300 days a year. For my 80-100 nights, it’s not worth the space.

Zone 7: Garage/Bike Storage (Optional But Useful)

If you’re into biking, surfing, climbing, or any activity with bulky gear, dedicated storage matters.

Options:

Rear garage:

  • Bed raises up or slides forward
  • Bikes/surfboards fit underneath or behind
  • 1.0m x 1.7m x 0.6m high = enough for 2 bikes
  • Access from rear doors

Roof rack:

  • 2-4 bikes on top
  • Pros: Doesn’t take internal space
  • Cons: Height issues (car parks, ferries), theft risk, wind noise, fuel penalty

Internal rail system:

  • Bikes hang from ceiling or wall
  • Saves floor space
  • Still takes up room (bikes are big)

Rear-mounted rack:

  • Bikes on the back (requires rear carrier)
  • Pros: Easy access, doesn’t affect height
  • Cons: Blocks rear access, theft risk, weight on rear door

My approach: Removable bed front section. Takes 2 minutes to remove (4 bolts). Bikes fit in the space where bed was (1.2m x 1.7m x 1.0m high). Then I reconstruct the bed with the bikes underneath if we’re sleeping there, or leave it open for travel days.

Not perfect but works. I can carry 2 bikes internally when needed without permanently dedicating space to them.

Common Layout Types (And What Works In Real Life)

Let me break down the most common layouts and the reality of living with them.

Layout 1: Fixed Bed Across Back + Side Kitchen

Setup:

  • Bed across full width at back (1.9m x 1.4-1.7m)
  • Kitchen along one side (80-100cm long)
  • Seating opposite kitchen
  • Storage: underbed, overhead, kitchen cupboards

Pros:

  • Comfortable bed (uses full width)
  • Good kitchen space
  • Natural workflow (kitchen opposite seating)
  • Relatively simple to build
  • Works for couples

Cons:

  • Bed takes up permanent space (can’t use for anything else)
  • Limited rear access (rear doors blocked by bed)
  • Less flexible than modular options

Best for: Regular weekend trips, couple without bikes/bulky gear, people who prioritize comfortable sleeping

This is what I have. Works brilliantly for 80-90% of our trips. The 10% where we want bikes is slightly awkward but manageable.

Cost to build: £650-£900 (furniture materials + mattress)

Layout 2: Rock and Roll Bed + Kitchen

Setup:

  • Rock and roll bed (doubles as seating)
  • Kitchen along one side
  • Rear area open (garage space)

Pros:

  • Doubles as seating during day
  • Rear access clear (bikes, gear)
  • Space-efficient
  • Quick conversion bed ↔ seating

Cons:

  • Rock and roll beds expensive (£1,200-£2,500)
  • Not as comfortable as proper bed
  • Cushions must be arranged/rearranged constantly
  • Limits rear door access when in bed mode

Best for: Weekend warriors who want seating space during day, people who need rear access, solo travelers

I tried this. Hated the bed comfort. Loved the flexibility. Would only use again if I was doing very short trips (2-3 nights maximum).

Cost to build: £1,800-£3,200 (rock and roll bed + kitchen)

Layout 3: Side-to-Side Bed + Rear Kitchen

Setup:

  • Bed along one side (up to 1.2m wide x 1.9m long)
  • Kitchen across the back
  • Open living space in middle
  • Often with pop-top for extra head height

Pros:

  • Living area feels spacious
  • Easy to move around
  • Rear kitchen accessible from outside
  • Good for one person or couple in SWB van

Cons:

  • Bed narrower (challenging for couples)
  • Kitchen less convenient in bad weather (rear doors)
  • More complex build

Best for: Solo travelers, SWB vans, people who want open feeling, those who cook outside often

Haven’t built this myself but driven a mate’s setup. Felt spacious but that narrow bed would drive me mad.

Cost to build: £700-£1,100

Layout 4: Full-Width Bed With Lift-Up Front (Garage Under)

Setup:

  • Full-width bed at back (1.9m x 1.4-1.7m)
  • Front section lifts up or slides forward
  • Bikes/gear stored underneath
  • Kitchen and living area up front

Pros:

  • Comfortable bed when sleeping
  • Garage space when traveling
  • Best of both worlds
  • Good use of space

Cons:

  • Requires lifting mechanism (gas struts or slides)
  • More complex to build
  • Must clear bed to access garage
  • Can be heavy to lift

Best for: Active people who need gear storage, couples who want comfortable bed, those willing to build more complex system

My mate has this. Uses it brilliantly. But he’s more mechanically minded than me. I’d probably cock up the lifting mechanism.

Cost to build: £900-£1,400 (includes lifting hardware)

Layout 5: L-Shaped Living Area With Pull-Out Bed

Setup:

  • Seating in L-shape (dinette style)
  • Table in center
  • Bed pulls out from seating or converts from seating
  • Kitchen separate

Pros:

  • Spacious living area during day
  • Good for socializing
  • Bed hidden when not in use
  • Works for families

Cons:

  • Must convert bed every night/morning
  • Conversion can be faff
  • Less comfortable than fixed bed usually
  • Takes time to set up

Best for: Families with kids, people who entertain others, those who use van as daytime living space, people who prioritize sitting space over sleeping comfort

Tried a version in van #2. The conversion process got old fast. After two weeks I just left it as a bed permanently and the whole dinette idea was pointless.

Cost to build: £800-£1,300

Layout 6: Minimalist (Mattress on Floor + Portable Everything)

Setup:

  • Mattress directly on floor (or low platform)
  • Portable camping kitchen
  • Plastic boxes for storage
  • Fold-up table and chairs

Pros:

  • Ultra-cheap (£200-£400 total)
  • Completely flexible
  • Can remove everything
  • Use van for work during week
  • Easy to change

Cons:

  • Less comfortable
  • Feels temporary
  • Not weather-sealed (everything moves)
  • Looks messy
  • No fixed kitchen means less convenient cooking

Best for: People testing vanlife before committing, those on tiny budget, people who need work van during week, minimalists

Started here with van #1. Worked for testing the concept. Upgraded to fixed furniture after 6 months because I was fed up with things sliding around.

Cost: £200-£400

The Planning Process (How to Actually Design Your Layout)

Right. You understand your space, your needs, and common layouts. Now how do you actually design YOUR layout?

Step 1: Measure Everything (Obsessively)

What to measure:

Van dimensions:

  • Internal length (cargo area only)
  • Internal width (narrowest point – usually wheel arches)
  • Internal height (measure in multiple places – vans aren’t uniform)
  • Wheel arch intrusion (they eat floor space)
  • Pillar positions (they limit where furniture can go)
  • Window positions (affects furniture placement)
  • Door opening sizes (affects access for furniture installation)

Your body dimensions:

  • Your height (affects bed length, standing areas)
  • Shoulder width (affects passageways)
  • Reach height (affects overhead storage)
  • Comfortable seating dimensions

Your gear dimensions:

  • Bikes (length, width, height)
  • Storage boxes you already own
  • Fridge size you’re considering
  • Camping chairs you use

I made cardboard templates of our bikes. Saved me from building a garage that was 5cm too short.

Tools for measuring:

  • Tape measure (obvious)
  • Laser measure (£25-£45, worth it for accuracy)
  • Spirit level (vans aren’t level – affects furniture)
  • Notepad (write everything down – you’ll forget)

Step 2: Make Cardboard Mockups (Seriously)

This sounds ridiculous. It’s the most valuable thing I did for van #4.

What I did:

  1. Bought cheap cardboard boxes from moving company (£20 for 10 boxes)
  2. Made furniture-sized boxes:
    • Bed: 1.9m x 1.4m x 0.45m high
    • Kitchen unit: 0.9m x 0.5m x 0.9m high
    • Seating: 0.8m x 0.4m x 0.45m high
  3. Placed them in the van in different configurations
  4. Got in, moved around, pretended to cook, pretended to sleep
  5. Adjusted positions

What I learned:

  • My planned kitchen was 10cm too long (would’ve blocked access to bed)
  • The overhead storage I planned was claustrophobic (changed to shorter cupboards)
  • I needed 70cm width for walkway (planned for 60cm – too narrow)
  • The table I wanted wouldn’t fit where I thought

Saved me from building £400 of furniture in the wrong place.

If you skip one step in this guide, don’t skip this one.

Step 3: Draw It Out (Multiple Times)

Tools:

Paper and pencil (my preference):

  • Free
  • Quick to iterate
  • Can sketch while sitting in the van
  • Draw to scale (graph paper helps)
  • I use 1 square = 10cm

Computer software:

  • SketchUp (free version available)
  • Autodesk Fusion 360 (free for personal use)
  • Sweethome3D (free, easy to learn)
  • Detailed 3D models
  • Can do proper measurements
  • Looks professional

Mobile apps:

  • MagicPlan
  • RoomScan
  • Various floor plan apps
  • Good for quick layouts
  • Less detailed than computer software

I use paper first for rough concepts, then move to SketchUp for final design. Paper is faster for iterating. SketchUp is better for final details and measurements.

Draw multiple views:

  • Plan view (looking down from above)
  • Side elevation (looking from side)
  • Front elevation (looking from rear/front)
  • 3D perspective if possible

Step 4: Test Your Design (Before Building Anything)

Questions to ask:

Movement flow:

  • Can you walk from door to bed without climbing?
  • Can you reach the kitchen from seating?
  • Can you get to storage without moving everything else?
  • Is there a natural traffic flow?

Daily tasks:

  • Can you cook while someone else is in the van?
  • Can one person sleep while another is awake?
  • Can you change clothes without sitting on the bed?
  • Can you access the fridge without asking someone to move?

Access and entry:

  • Can you carry furniture in through the door? (Check dimensions!)
  • Can you access underbed storage without removing the bed?
  • Can you reach overhead storage without a step ladder?

Emergency situations:

  • Can you get out quickly if needed?
  • Is the fire extinguisher accessible?
  • Can you reach the door from the bed?

Real-world scenarios to test mentally:

Scenario 1: Rainy day

  • You’re both inside all day
  • Someone’s working on laptop
  • Someone’s reading
  • You both need lunch
  • Where does everyone sit? How do you cook? Where does wet gear go?

Scenario 2: Getting ready in the morning

  • One person needs to cook breakfast
  • One person needs to get dressed
  • Can this happen simultaneously?
  • Where’s the traffic conflict?

Scenario 3: Loading for a trip

  • Food shopping for a week
  • Clothes for two people
  • Outdoor gear (bikes, wetsuits, whatever)
  • Where does it all go?
  • How long to pack?

I mentally tested these for van #4. Found several issues:

  • Couldn’t both get dressed simultaneously (would bump into each other)
  • Kitchen blocked access to bed (one person trapped if other cooking)
  • Revised layout to add 15cm more walkway space

Step 5: Budget Reality Check

Every layout has a cost. More complex = more expensive.

Budget by layout complexity:

Simple (£600-£1,000):

  • Fixed bed (basic frame + mattress)
  • Simple kitchen (worktop, hob, basic storage)
  • Minimal seating
  • Open storage

Standard (£1,200-£2,000):

  • Fixed bed with storage underneath
  • Proper kitchen with cupboards and drawer
  • Seating with storage
  • Overhead cupboards
  • Wall lining and flooring

Complex (£2,500-£4,000):

  • Rock and roll bed or lift-up bed system
  • Extensive kitchen with multiple cupboards
  • Dinette setup or complex seating
  • Lots of custom furniture
  • High-end finishes

Very Complex (£5,000+):

  • Custom mechanical systems (bed lifts, pull-outs)
  • Wet room installation
  • Built-in appliances (oven, fridge, etc.)
  • Professional joinery
  • Bespoke everything

My van builds:

  • Van #1: £850 (basic, lots of compromises)
  • Van #2: £2,100 (complex, mostly wasted because I redesigned it)
  • Van #3: £1,600 (good but needed modifications)
  • Van #4: £1,350 (optimized from previous learning)

The expensive lessons from van #2 made van #4 cheaper because I knew exactly what worked.

Common Layout Mistakes (That I Made So You Don’t Have To)

Mistake 1: Prioritizing Aesthetics Over Function

What I did: Van #2, I designed a beautiful L-shaped kitchen with lovely curved edges, matching overhead cupboards, and a dinette area that looked Instagram-perfect.

Result:

  • Couldn’t stand in the right place (head hit overhead cupboard)
  • Curved edges wasted 15cm of usable worktop
  • Dinette looked great but we sat there maybe 10 times
  • Cooking was awkward because everything was slightly wrong position

Cost: £650 to build + £480 to rebuild = £1,130 wasted

Lesson: Function first. Always. If it doesn’t work well, it doesn’t matter how good it looks.

Mistake 2: Not Leaving Enough Walkway Space

What I did: Designed everything to maximize furniture. Left 55cm walkway.

Result: Constantly banging into things. Couldn’t walk past someone. Felt cramped and claustrophobic.

Fix: Redesigned to leave 70cm walkway. Immediately felt more spacious.

Lesson: Minimum 65cm walkway. 70-75cm is comfortable. Don’t sacrifice this for extra storage.

Mistake 3: Building Everything Fixed

What I did: Van #2, everything was permanently fixed. Looked built-in and professional.

Result: Couldn’t adapt to different trips. Couldn’t fit bikes without removing furniture. Couldn’t change anything without major work.

Lesson: Modular is better. Fixed what must be fixed (kitchen, bed frame). Removable everything else.

Current van:

  • Bed front section: 4 bolts (removable in 2 minutes)
  • Seating cushions: Lift off (storage access)
  • Table: Separate camping table (stored when not needed)
  • Storage boxes: Not built in (can remove, reorganize, replace)

Mistake 4: Overhead Storage Too Deep

What I did: 40cm deep overhead cupboards in van #2. Thought more storage = better.

Result:

  • Hit my head constantly
  • Felt claustrophobic
  • Things disappeared at the back
  • Rarely used the back half

Lesson: Maximum 30cm deep for overhead. 25cm is better. Shallow and long beats deep and high.

Mistake 5: No Thought to Installation

What I did: Built beautiful furniture in my workshop. Couldn’t get it through the van door.

Result: Had to disassemble it, modify it, reassemble inside. Three extra days of work.

Lesson:

  • Check door dimensions (including angles)
  • Build in sections if needed
  • Or build inside the van (more awkward but guarantees it fits)

Mistake 6: Ignoring Weight Distribution

What I did: Put all heavy stuff (batteries, water, tools) at the back in van #1.

Result: Van felt tail-heavy. Handling was weird. Suspension sagged at back.

Lesson: Distribute weight evenly. Heavy items (batteries, water tanks) should be low and central. Check payload regularly.

My current weight distribution:

  • Batteries: Under seating (central, low)
  • Water: Under kitchen (front area, low)
  • Tools: Distributed in underbed storage (spread across width)
  • Heavy items: Never all in one area

Mistake 7: Not Planning for Condensation

What I did: Overhead cupboards with no ventilation.

Result: Condensation formed inside cupboards. Clothes got damp. Had to drill ventilation holes afterward.

Lesson: Ventilation matters everywhere. Cupboards need it. Under-bed storage needs it. Air must circulate.

Real-World Examples From My Builds

Let me give you the actual layouts I’ve built with honest assessments.

Van #1: VW Transporter T5 (Learning Experience)

Specs: SWB, standard roof, 2008, 1.7m x 1.7m x 1.4m interior

Layout:

  • Rock and roll bed (full width)
  • Tiny kitchen (60cm) along side
  • Minimal storage (underbed only)
  • No overhead cupboards
  • Portapotti under bed

What worked:

  • Rear access clear for bikes
  • Rock and roll was okay for seating
  • Simple and cheap (£850 total)

What didn’t:

  • Rock and roll bed uncomfortable for sleeping
  • Kitchen too small (constantly running out of space)
  • Not enough storage (bags everywhere)
  • Felt cramped constantly

Duration: Used for 10 months then sold

Would I build this again? No. Good learning experience but fundamentally limited by SWB size and poor layout choices.

Van #2: Ford Transit Custom MWB (The Beautiful Mistake)

Specs: MWB, medium roof, 2015, 2.6m x 1.7m x 1.75m interior

Layout (original):

  • L-shaped kitchen (gorgeous but huge)
  • Dinette seating area with table
  • Bed across back (1.9m x 1.35m – too narrow)
  • Gas oven + two-burner hob
  • Lots of overhead storage (too deep)

What worked:

  • Looked professional
  • Lots of worktop space
  • Good lighting
  • Proper electrical system

What didn’t:

  • Dinette barely used (wasted space)
  • Bed too narrow (uncomfortable for two)
  • Kitchen dominated the van
  • Overhead storage hit my head
  • Oven useless

Cost: £2,100 initial build

Layout (after redesign 6 months later):

  • Straight kitchen (90cm) along one side
  • Ripped out dinette
  • Built simple bench seating
  • Widened bed to 1.4m
  • Removed oven
  • Shorter overhead cupboards

Cost of redesign: £480 + my time

What worked after redesign:

  • Much better proportions
  • Comfortable bed
  • Kitchen still good but not dominating
  • More open feeling

Duration: Used for 3 years total, sold when upgrading

Would I build this again? The redesigned version, yes. Original version, absolutely not.

Van #3: Ford Transit Custom MWB (Getting There)

Specs: MWB, medium roof, 2016, 2.6m x 1.7m x 1.75m interior

Layout:

  • Fixed bed across back (1.9m x 1.4m)
  • Side kitchen (90cm)
  • L-shaped seating
  • Overhead storage above bed
  • Underbed storage organized with boxes

What worked:

  • Comfortable bed finally
  • Kitchen perfect size and position
  • Good storage solutions
  • Proper ventilation (learned from van #2)

What didn’t:

  • Everything was permanently fixed (couldn’t fit bikes)
  • Seating was nice but took up lots of space
  • Some wasted space in corners

Modifications after 6 months:

  • Made bed front section removable
  • Reduced seating to simple bench
  • Added flexibility

Duration: Used for 2 years, sold when moving to current van

Would I build this again? Very close. 80% right. Just needed more flexibility from the start.

Van #4: Ford Transit Custom MWB (Current – Finally Got It Right)

Specs: MWB, medium roof, 2017, 2.6m x 1.7m x 1.75m interior

Layout:

  • Fixed bed across back (1.9m x 1.4m)
  • Front section removable (4 bolts)
  • Side kitchen (90cm) with two-burner hob and sink
  • Simple bench seating (L-shaped, minimal)
  • Storage: underbed (boxes), overhead (shallow cupboards), kitchen cupboards
  • 20L fridge under seating
  • Diesel heater under bed
  • Separate camping table (stored, not built-in)

What works:

  • Comfortable bed (10cm memory foam mattress)
  • Kitchen perfect for cooking real meals
  • Seating adequate for two people
  • Modular – can adapt to different trips
  • Bikes fit when needed (remove bed front)
  • Good storage (though never quite enough)
  • 70cm walkway feels spacious

What doesn’t:

  • Still not quite enough storage (is there ever?)
  • Seating could be slightly comfier (cushions are okay not great)
  • No dedicated workspace (use worktop but not ideal)

Cost: £1,350 (learned from previous mistakes)

Duration: 18 months so far, no plans to change

Would I build this again? Yes. This is the one I’d replicate. Small improvements possible but fundamentally sound.

My Final Recommendations

After four builds, here’s what I’d tell my younger self:

1. Start with needs, not wants

Don’t design for Instagram. Design for your actual life. If you’re doing weekend trips, you don’t need a shower. If you never cook elaborate meals, you don’t need a huge kitchen.

2. Modular beats permanent

Fix what must be fixed. Make everything else removable or adaptable. Your needs will change. Your layout should adapt.

3. Comfort beats aesthetics

A comfortable bed matters more than matching cupboards. A functional kitchen matters more than curved edges. Prioritize accordingly.

4. Leave space to move

70cm minimum for walkways. Don’t cram everything in. Space to move makes a small van feel bigger than cramming more furniture.

5. Storage everywhere

Every cubic centimeter counts. Underbed, overhead, under seats, door pockets, magnetic strips. You’ll always need more storage than you plan for.

6. Test before building

Cardboard mockups. Sketches. Multiple iterations. The hour you spend testing saves the week you spend rebuilding.

7. Simple is better

Complex mechanisms break. Simple furniture lasts. Rock and roll beds are cleverer than fixed beds but less reliable. Fold-out tables are fancier than camping tables but more things to fail.

8. Learn from others but design for yourself

Look at other layouts for inspiration. But your needs are unique. Don’t copy someone else’s layout exactly.

9. Budget 20% extra

Every build goes over budget. Materials cost more than planned. You’ll change things midway. Budget accordingly.

10. Accept imperfection

No layout is perfect. You’ll always find things you’d change. Build something good enough and start using it. You’ll learn more from living in it than planning it.

The Layout I’d Build If Starting Fresh Today

If I bought a new MWB Transit Custom tomorrow and was building from scratch, here’s exactly what I’d do:

Bed:

  • Fixed across back (1.9m x 1.4m)
  • Slat base (18mm ply + timber frame + slats)
  • Front section bolted (4 bolts, removable)
  • Back section screwed (permanent)
  • Storage underneath (3 x 84L boxes)
  • Cost: £180 + £285 mattress = £465

Kitchen:

  • Along side, 90cm long
  • Worktop: 90cm x 50cm (28mm beech)
  • Two-burner gas hob
  • 32cm round sink
  • Cupboard underneath (60L)
  • Drawer for utensils
  • Overhead cupboard (25cm deep, 80cm long, 30cm high)
  • Cost: £385

Seating:

  • Simple L-bench (80cm x 40cm along side, 60cm x 40cm along back)
  • Storage underneath (fridge 20L + electrical + misc)
  • Cushions on top
  • Cost: £95

Storage:

  • Overhead above bed (1.8m x 35cm x 30cm deep)
  • Underbed (organized boxes)
  • Under-seating
  • Kitchen cupboards
  • Door pockets and hooks
  • Cost: £120 (shelving, brackets, boxes, hooks)

Table:

  • Removable camping table (stored under bed)
  • Cost: £35

Electrical:

  • 105Ah lithium battery
  • DC-DC charger
  • 200W solar
  • LED lights
  • USB sockets
  • Cost: £1,170 (from previous guide)

Heating:

  • Diesel heater
  • Cost: £410 (from previous guide)

Plumbing:

  • Jerry cans + Shurflo pump + sink + waste
  • Cost: £241 (from previous guide)

Total furniture cost: £1,100 Total conversion cost (including electrical, heating, plumbing): £3,356 (plus insulation £635, plus van £12,000-£14,000)

Total project: £16,000-£18,000

Result: Comfortable year-round camper for two people, suitable for weekend trips to month-long tours, with flexibility for bikes when needed, and built to last.

Final Thoughts

Layout design is where your conversion succeeds or fails. Get it right and everything works smoothly. Get it wrong and you’ll spend months frustrated or years rebuilding.

I’ve been in both camps. Three redesigns taught me more than any book could.

The perfect layout doesn’t exist. The right layout for you depends on your life, your needs, your body, your hobbies, your budget, and your tolerance for compromise.

Start with cardboard boxes. Seriously. It’s the best £20 you’ll spend.

Think about function before aesthetics. Test everything before building. Plan for flexibility. Accept imperfection.

And when you cock it up (you probably will, at least a bit), don’t feel bad. Learn from it, fix it, and move on.

That’s what I did. Three times.

Now stop reading and go play with cardboard boxes in your van. The perfect layout is hiding in there somewhere.

Got questions about your specific layout? steve@theferalway.com — I’ve probably made your mistake already and can tell you how I fixed it.

Continue Reading
By
Insulation & Soundproofing

Insulation And Soundproofing for Campervans

No Comments
Insulation & Soundproofing for Campervans

I’ve insulated four campervans. The first one grew mould within three months. The second was freezing in winter because I believed the marketing hype about reflective foil. The third was better but still had condensation issues I didn’t fix until I ripped half of it out six months later. The fourth? Finally got it right. This experience led me to understand the importance of Insulation And Soundproofing for Campervans.

That’s £1,400 worth of insulation materials I’ve ripped out and binned because I did it wrong. Another £280 in mould treatment and repainting. And countless nights shivering in Scotland or sweating in Spain because I convinced myself that 10mm of bubble wrap would somehow defy physics.

This guide is everything I wish I’d known before I started. Not the marketing claims. Not the YouTube videos where everything works perfectly. The actual reality of insulating a metal box in the UK, what genuinely works, and how to avoid the expensive mistakes I made.

Why Insulation Actually Matters (More Than You Think)

Before we get into materials and techniques, understand this: insulation and soundproofing for campervans is the single most important decision in your entire conversion. Get it wrong and nothing else matters. Your £800 diesel heater won’t help if all the heat escapes through the roof. Your expensive ventilation system won’t stop condensation if cold metal meets warm air.

I’ve met people who spent £15,000 on beautiful furniture, fancy electrical systems, and Instagram-worthy interiors, then cheaped out on insulation. Every single one regrets it.

What proper insulation does:

  • Keeps you warm in winter (obviously)
  • Keeps you cool in summer (less obvious but equally important)
  • Prevents condensation (the real killer)
  • Reduces noise (makes the van liveable)
  • Saves fuel (your heater runs less)
  • Protects your build (mould destroys furniture and health)

What it costs to get it right:

  • Budget option: £250-£400 for a medium wheelbase van
  • Decent job: £400-£600
  • Premium materials: £600-£900

What it costs to get it wrong:

  • Ripping it out and starting again: £300-£600 in new materials
  • Mould treatment: £80-£150
  • Repainting damaged areas: £60-£120
  • Lost time: 2-4 days of work redone
  • Health issues from mould: Priceless (and expensive)

I’ve been in both camps. Trust me, spending £500 upfront beats spending £800 fixing it later.

Understanding Heat Transfer (The Boring But Critical Bit)

Skip this if you just want to be told what to buy. But if you want to understand WHY certain materials work and others don’t, this matters.

Heat moves three ways:

1. Conduction — Heat moving through solid materials (metal van walls conducting cold inside)

2. Convection — Heat moving through air currents (cold air sinking, warm air rising)

3. Radiation — Heat moving as infrared energy (like sunlight warming the van roof)

Different insulation materials tackle different types of heat transfer. This is why people get confused.

R-Value explained:

R-value measures thermal resistance. Higher number = better insulation. But thickness matters too.

  • Celotex 25mm = R-value of 1.15
  • Celotex 50mm = R-value of 2.30
  • Sheep’s wool 50mm = R-value of 1.32
  • Reflectix 10mm = R-value of 0.15 (basically useless without air gaps)

The key number is thermal conductivity (λ or lambda), measured in W/mK (watts per metre-kelvin):

  • Lower = better
  • PIR boards (Celotex/Kingspan): 0.022 W/mK (excellent)
  • Sheep’s wool: 0.038 W/mK (good)
  • XPS foam: 0.034 W/mK (good)
  • Bubble foil alone: 0.041 W/mK (poor)

Thermal bridging (the sneaky heat thief):

Metal conducts heat really well. Your van is a metal box with ribs, pillars, and structural elements. These create “thermal bridges” where heat bypasses your insulation entirely.

I didn’t understand this in my first build. I filled every gap with insulation, thinking more = better. But the metal ribs were still conducting cold straight through, creating cold spots and condensation.

The solution: You can’t eliminate thermal bridging completely in a van, but you can minimize it by:

  • Breaking contact between metal and interior surfaces
  • Leaving air gaps for ventilation
  • Using insulation with good thermal resistance
  • Accepting some thermal bridging is inevitable

Insulation Materials: What Actually Works

I’ve used pretty much every material available. Here’s the honest truth about each.

Celotex / Kingspan (PIR Rigid Boards)

What it is: Polyisocyanurate foam boards with foil facing on both sides. This is what most professional converters use, and it’s what I use now.

Cost: £4-£8 per square metre depending on thickness and where you buy

Thicknesses available: 25mm, 50mm, 75mm, 100mm (for vans, you’ll mostly use 25mm and 50mm)

Thermal performance:

  • λ = 0.022 W/mK (excellent)
  • 25mm gives R-value of 1.15
  • 50mm gives R-value of 2.30

Pros:

  • Best thermal performance for thickness
  • Moisture resistant (doesn’t absorb water)
  • Rigid — easy to cut and fit between ribs
  • Foil facing acts as radiant barrier
  • Widely available (Wickes, Screwfix, Travis Perkins)
  • Relatively affordable

Cons:

  • Can’t compress into curves (you’ll have gaps)
  • Not eco-friendly (plastic foam)
  • Produces toxic fumes if it burns (though unlikely in a van)
  • Needs careful installation to avoid thermal bridging

Where I use it:

  • 50mm on the roof (between ribs)
  • 25mm on the walls (between ribs)
  • 25mm on the floor (under subfloor)

Installation tips:

Cut it 5-10mm oversize for friction fit between ribs. Use expanding foam around edges ONLY — never behind the board (creates thermal bridging). Leave 10-15mm air gap between metal and insulation for ventilation where possible.

Real-world performance:

In my current van with 50mm Celotex on the roof and 25mm on walls:

  • Winter night at -2°C outside: 8-10°C inside without heating (about 10°C gain from body heat and residual warmth)
  • With diesel heater running: Maintains 18°C using 0.15-0.2L fuel per hour
  • Summer day at 28°C outside: 22-24°C inside in shade (4-6°C cooler)

Cost for medium wheelbase van:

  • Roof (50mm): £165 (8 sheets at 2400x1200mm)
  • Walls (25mm): £95 (6 sheets)
  • Floor (25mm): £50 (3 sheets)
  • Total: £310

Sheep’s Wool (Thermafleece)

What it is: Actual sheep’s wool, treated against moths and fire-proofed. Eco-friendly option that’s gaining popularity.

Cost: £8-£15 per square metre (more expensive than PIR)

Thermal performance:

  • λ = 0.038 W/mK (good but not as good as PIR)
  • 50mm gives R-value of 1.32
  • 100mm gives R-value of 2.64

Pros:

  • Breathable (handles moisture brilliantly — this is huge)
  • Eco-friendly and sustainable
  • Naturally fire-resistant
  • Compresses into awkward spaces
  • No need for vapor barriers (wool regulates moisture naturally)
  • Feels nice to work with (no itching like fiberglass)
  • Excellent sound absorption

When considering a campervan build, remember that Insulation And Soundproofing for Campervans can significantly enhance your comfort and quality of life on the road.

Cons:

  • More expensive per square metre
  • Takes up more space for equivalent R-value
  • Harder to source (not in every builders’ merchant)
  • Moths can be an issue if not properly treated
  • Heavier than PIR
  • Can settle over time in vertical applications

Where it works best:

  • Wall cavities where you want breathability
  • Areas where you can fit thicker insulation
  • Full-time living situations (the breathability matters more)
  • Awkward curves and gaps where rigid boards don’t fit

Installation tips:

Wear gloves even though it’s softer than fiberglass. Stuff it in but don’t compress it too much — wool insulates by trapping air. Use around 100mm for walls and roof if you have the space. Secure with mesh or fabric to prevent it falling down.

Real-world performance:

I used wool in van #2 for the walls. Thermal performance was decent but not quite as good as PIR of equivalent thickness. The big win was moisture management — I had far less condensation compared to van #1. But it was more expensive and took up more interior space.

Cost for medium wheelbase van (100mm thickness):

  • Full coverage: £450-£650 depending on supplier

My verdict: Brilliant if you’re building for full-time living and can afford the space and cost. For weekend/part-time use, PIR gives better thermal performance per millimetre.

XPS Foam (Extruded Polystyrene)

What it is: Closed-cell foam boards, usually pink or blue. Common in building insulation.

Cost: £4-£7 per square metre

Thermal performance:

  • λ = 0.034 W/mK (good)
  • 50mm gives R-value of 1.47

Pros:

  • Moisture resistant
  • Relatively affordable
  • Easy to cut and shape
  • Lighter than PIR

Cons:

  • Not as good as PIR thermally
  • Can compress over time
  • Less widely available in useful sizes
  • Doesn’t have foil facing (need separate vapor barrier)

My experience: I tried this in one section of van #3. It worked fine but wasn’t noticeably better than PIR, and PIR was easier to source in the sizes I needed.

Verdict: Decent option if you can’t get PIR, but PIR is generally better for vans.

Reflectix / Bubble Foil (The Marketing Lie)

What it is: Bubble wrap with foil facing. Marketed as miracle insulation.

Cost: £2-£5 per square metre

Thermal performance:

  • λ = 0.041 W/mK when used correctly (poor)
  • Without air gaps: R-value of about 0.15 (useless)
  • With 25mm air gaps on both sides: R-value of 1.0-1.5 (better but impractical in a van)

The marketing claim: “Reflects 97% of radiant heat!”

The reality: Only works if you have 25mm air gaps on BOTH sides. In a van, you can’t create these air gaps practically. Stuck flat against metal or trapped behind panels, it’s basically expensive bubble wrap.

Pros:

  • Very cheap
  • Lightweight
  • Easy to install
  • Works as a vapor barrier
  • Good for blocking radiant heat IF you have air gaps

Cons:

  • Terrible insulation without air gaps
  • Marketing claims are misleading
  • People use it as primary insulation and wonder why they’re cold
  • Creates condensation issues if used incorrectly

Where it actually works:

Window covers: With an air gap between glass and foil, it reflects heat back out in summer and keeps heat in during winter. This is a good use.

Vapor barrier: Over proper insulation (PIR or wool), it provides a vapor barrier to prevent moisture reaching cold metal. This is how I use it.

NOT as primary insulation. Just don’t. I tried this in van #1 because I believed the marketing. I froze. The maths doesn’t lie.

My verdict: Useful as part of a system (vapor barrier or window covers), useless as primary insulation. Anyone telling you 10mm of bubble foil is adequate insulation for a UK winter is either lying or has never actually used it.

Spray Foam (Professional Application)

What it is: Two-part polyurethane foam sprayed into all cavities by professionals. Expands to fill every gap.

Cost: £800-£2,000 for professional application in a medium wheelbase van

Thermal performance:

  • λ = 0.026-0.030 W/mK (excellent)
  • Fills every gap perfectly
  • No thermal bridging at all

Pros:

  • Best possible coverage
  • Fills every cavity and awkward gap
  • No thermal bridging
  • Excellent R-value
  • Air-tight seal
  • Professional application means it’s done right

Cons:

  • Expensive
  • Can void van warranty (check with manufacturer)
  • Makes van panels impossible to remove later
  • Can trap moisture if not done correctly
  • Permanent — you can’t easily change your mind
  • Needs professional installation (not DIY)

My experience: I’ve never used it personally but I’ve helped a mate whose van was spray foamed. Performance was excellent — genuinely the best-insulated van I’ve been in. But when he needed to access wiring later, it was a nightmare. Had to cut away foam and it made a horrible mess.

My verdict: Only worth it if:

  • You have the budget (£1,500+ minimum)
  • This is your forever van
  • You’re 100% sure of your electrical and plumbing layouts
  • You’re not planning to make changes later

For most people doing DIY conversions, PIR boards give you 90% of the performance at 25% of the cost, with the flexibility to change things later.

Closed-Cell Foam Sheets

What it is: Thin closed-cell foam sheets, usually 3-10mm thick. Sometimes used for soundproofing.

Cost: £1-£3 per square metre

Thermal performance: Poor (λ = 0.040 W/mK for 10mm)

Where it’s useful:

  • Sound deadening (we’ll cover this later)
  • Moisture barrier
  • Gap filling

Where it’s not useful:

  • Primary insulation (too thin, poor R-value)

Multifoil Insulation (Aluthermo, Actis, SuperQuilt)

What it is: Multiple layers of foil with wadding between them. Marketed as thin but high-performance.

Cost: £6-£12 per square metre

Thermal performance:

  • Claimed: R-value of 1.5-2.5 for 20-40mm thickness
  • Reality: Only achieves this with air gaps, proper installation, and ideal conditions
  • Without air gaps: Similar to bubble foil (poor)

The controversy:

There’s ongoing debate about these products. Independent testing often shows lower performance than manufacturer claims, especially in retrofit applications like vans where you can’t maintain proper air gaps.

My experience: I tried Actis Hybris in van #2 on the advice of someone who swore by it. Thermal performance was disappointing. Maybe I installed it wrong (the instructions are complex), but PIR was simpler and performed better.

My verdict: Too expensive for questionable performance. PIR is cheaper, simpler, and has proven performance that doesn’t rely on perfect installation conditions.

Soundproofing: The Other Half of the Puzzle

Insulation and soundproofing are different. Insulation stops heat transfer. Soundproofing stops noise. Some materials do both. Most don’t.

An uninsulated, unsoundproofed van is a tin can. Every stone hitting the underside sounds like a gunshot. Every raindrop is amplified. Road noise is constant. You can’t have a conversation at motorway speeds.

Soundproofing transforms the experience. It’s the difference between a commercial van and a vehicle you actually want to spend time in.

How Sound Moves

Sound vibrates through solid materials (the metal van body) and travels through air. To stop it, you need:

1. Mass — Heavy materials that vibrations can’t easily move through

2. Damping — Materials that absorb vibration energy and convert it to heat

3. Decoupling — Breaking the connection between vibrating surfaces

4. Absorption — Materials that trap sound waves (like foam or wool)

Soundproofing Materials

Dynamat / Silent Coat / Car Soundproofing Mats

What they are: Butyl rubber sheets with aluminum facing. You stick them to metal panels to dampen vibrations.

Cost:

  • Dynamat: £250-£400 for a van (premium brand)
  • Silent Coat: £180-£280 (what I use)
  • Budget alternatives: £80-£150 (eBay Chinese brands)

How they work: The butyl rubber absorbs vibration energy, preventing panels from resonating and amplifying noise.

Where to apply:

  • Floor (entire floor ideally)
  • Wheel arches (critical — stones hitting here are loud)
  • Roof (at least 50% coverage)
  • Door panels
  • Behind cab seats

Installation:

  1. Clean metal with panel wipe or isopropyl alcohol
  2. Warm the adhesive side with heat gun (makes it stick better)
  3. Cut to size for each panel
  4. Peel backing and apply
  5. Roll firmly with a roller to eliminate air bubbles and ensure contact

Critical: This needs to be above 15°C to stick properly. I tried applying Silent Coat in my garage in December. It wouldn’t stick. Had to wait until April.

Coverage recommendations:

You don’t need 100% coverage (despite what manufacturers claim). Focus on the noisiest areas:

  • Floor: 70-80% coverage (focus on wheel arches and rear)
  • Roof: 50-60% coverage
  • Doors: 60% coverage
  • Wheel arches: 100% coverage

My coverage:

  • Used 9 sheets of Silent Coat (each 4.6kg, 50cm x 80cm)
  • Covered about 70% of the floor, 60% of roof, wheel arches completely
  • Cost: £225
  • Time: 2 full days

Results: Massive difference. Before soundproofing, stones hitting the underside were painfully loud. After, they’re just a dull thump. Road noise reduced significantly. Rain is no longer deafening.

Sound absorption (foam/wool)

After damping the metal panels, you still have airborne noise. This is where sound-absorbing materials help.

Sheep’s wool is excellent for this — it absorbs sound far better than PIR boards. If you’ve used wool insulation, you’re already sorted. If you’ve used PIR, you might want to add some absorption.

Acoustic foam (like studio foam) can be added in cavities, but it’s usually overkill for a van. The insulation and interior lining provide enough absorption for most people.

My Actual Installation Process (What I Do Now)

This is the process I follow after learning from three failed attempts. This is for a medium wheelbase van using PIR boards.

Phase 1: Preparation (1 day)

1. Strip and clean:

  • Remove all panels, lining, anything attached to walls/roof/floor
  • Wire brush any surface rust
  • Treat rust with converter
  • Clean all metal with panel wipe
  • Let dry completely

2. Mark ribs and fixing points:

  • Mark where all ribs, pillars, and structural elements are
  • Identify where you’ll need to run cables later
  • Take photos for reference

3. Plan your layout:

  • Decide where furniture will attach (you’ll need blocking in these areas)
  • Identify areas that need service access (don’t fully seal these)

Phase 2: Soundproofing (2 days)

Day 1: Floor and wheel arches

Materials needed:

  • 6-8 sheets of Silent Coat or equivalent
  • Heat gun
  • Roller
  • Sharp knife
  • Panel wipe

Process:

  1. Clean floor thoroughly with panel wipe
  2. Warm each sheet with heat gun (makes it pliable)
  3. Cut to fit floor sections
  4. Peel and stick
  5. Roll firmly — this is critical, air bubbles reduce effectiveness
  6. Pay special attention to wheel arches (100% coverage here)
  7. Overlap sheets by 10-20mm at joins

Wheel arches: These get stone chips constantly. Cover them completely. I use two layers in the most exposed areas.

Day 2: Roof and doors

Same process. Focus on areas where you’ll hear noise most:

  • Roof above where you’ll sit/sleep
  • Door panels
  • Behind cab seats

Don’t bother soundproofing:

  • Areas that will be completely covered by furniture
  • Inside tiny cavities you can’t reach
  • The cab (unless you’re really bothered — it adds weight)

Phase 3: Insulation (3-4 days)

Day 1: Roof

Materials:

  • 50mm Celotex (8 sheets for medium wheelbase)
  • Expanding foam (5-6 cans of Soudal Gap Filler)
  • Sharp knife or saw
  • Measuring tape
  • Safety glasses (foam in eyes is not fun)

Process:

  1. Measure each section between ribs — They’re all slightly different. Don’t assume they’re the same width.
  2. Cut PIR boards 5-10mm oversize — You want a friction fit. If it’s too loose, it’ll rattle. Too tight and you’ll compress the ribs (not good).
  3. Test fit before foam — Make sure it fits snugly.
  4. Apply expanding foam around edges only — NOT behind the board. Foam behind creates thermal bridging. Foam around edges seals gaps and prevents air movement.
  5. Press board into place — It should friction fit between ribs.
  6. Leave 10-15mm air gap between metal and insulation — This is critical for ventilation. I use small spacers (pieces of plastic or foam) to maintain this gap.

Dealing with curves:

Roof curves toward the edges. PIR doesn’t bend. You’ll have gaps. Options:

  • Cut narrower strips that follow the curve
  • Use expanding foam to fill gaps (not ideal but works)
  • Use wool insulation in these areas (better)

I use option 3 — wool insulation in curved areas, PIR in flat sections.

Day 2: Walls

Same process but with 25mm PIR instead of 50mm.

Additional challenge: Windows. You need to insulate around window frames carefully. Leave expansion space (windows get hot in sun). Seal with flexible sealant, not rigid foam.

Cable routing: Before you insulate, think about where cables will run. I leave channels between insulation and metal for cables. Makes life much easier later.

Day 3: Floor

Floor insulation is non-negotiable. You lose massive amounts of heat through the floor in winter.

Two approaches:

Approach 1 (what I do):

  1. 25mm PIR laid directly on metal floor
  2. 12mm ply subfloor on top
  3. Screw through PIR and ply into original floor (use longer screws)
  4. This raises floor by 37mm (annoying but worth it)

Approach 2 (if you can’t lose height):

  1. 10-15mm PIR (not ideal but better than nothing)
  2. 6mm ply subfloor
  3. Raises floor by only 16-21mm

Critical floor consideration: Water and moisture can get under insulation from outside. Use closed-cell insulation (PIR or XPS), never wool. And leave drainage paths for any moisture to escape (small gaps at edges).

Day 4: Vapor barrier and awkward gaps

Vapor barrier: I use Reflectix or basic bubble foil over the PIR insulation as a vapor barrier. This prevents warm, moist interior air from reaching cold metal where it would condense.

Application:

  • Staple or tape over insulation
  • Overlap joints by 50-100mm
  • Tape all seams with aluminum tape
  • Don’t stress about perfect coverage — it’s an additional layer, not a critical seal

Fill gaps with expanding foam:

  • Around edges of PIR boards
  • Where ribs meet roof/walls
  • Where pillars create awkward corners

Don’t fill:

  • Behind insulation (thermal bridging)
  • Ventilation paths (you need air circulation)
  • Areas you need to access later

Phase 4: Battening (1 day)

Before you line the walls and ceiling, install battens (timber strips) to attach lining to.

Why battens matter:

  1. Create fixing points for lining (you can’t screw through PIR reliably)
  2. Create small air gap between insulation and lining (additional thermal break)
  3. Hide any uneven insulation

Batten specifications:

  • 25mm x 50mm timber (PAR — planed all round)
  • Treated timber if possible (moisture resistance)

Where to install:

  • Vertically on walls every 400-500mm
  • Across roof following ribs
  • Around all door and window frames
  • Wherever you plan to fix furniture

Fixing battens:

  • Use penny washers under screws (spreads load on the insulation)
  • Screw through batten, through insulation, into metal ribs
  • Check fixing depth — don’t penetrate roof/walls (water ingress)

Cost: £45-£65 for timber for a medium van

Phase 5: Quality Check (½ day)

Before you line over everything, check:

Ventilation paths: Air must be able to circulate. Check you haven’t sealed everything completely. I leave 10-15mm gaps at the top and bottom of walls.

Moisture management: Any water that gets in must be able to get out. Check drainage paths at floor level.

Cable routes: Can you run cables where you need them? Now is the time to install cable conduit or channels.

Thermal bridging: Are there obvious cold bridges you can address? Major ribs can’t be avoided, but check for accidental direct contact between interior surfaces and metal.

Gaps and holes: Fill any gaps that would allow air circulation through the insulation (defeats the purpose).

Common Mistakes (That I Made So You Don’t Have To)

Mistake 1: Using bubble foil as primary insulation

What I did: Van #1, I used 10mm Reflectix everywhere, believing the “reflects 97% of heat” marketing.

Result: Froze in Scotland in October. Condensation everywhere. Black mould on ceiling within 3 months.

Cost: £380 to rip out and redo with proper insulation.

Why it failed: Reflectix needs air gaps to work. I had none. Without air gaps, it’s just thin bubble wrap.

The fix: Ripped it all out. Installed 50mm PIR on roof, 25mm on walls. Problem solved.

Mistake 2: No air gaps for ventilation

What I did: Filled every single cavity completely with insulation. No air gaps anywhere. Proud of myself for thorough coverage.

Result: Condensation behind insulation. Mould on metal panels. Rusting floor around sliding door runners.

Cost: £180 in rust treatment and repainting. Plus the time to partially dismantle and redo.

Why it failed: Moisture needs somewhere to go. Sealed completely, it gets trapped and causes problems.

The fix: Left 10-15mm air gaps between metal and insulation. Added ventilation paths top and bottom of walls. Problem solved.

Mistake 3: Applying soundproofing in cold weather

What I did: Applied Silent Coat in my garage in December. Temperature was about 8°C.

Result: Half the sheets didn’t stick properly. Came loose after a month of driving.

Cost: £80 for replacement sheets.

Why it failed: Adhesive needs warmth to bond properly. Below 15°C, it doesn’t stick well.

The fix: Waited for warmer weather. Used heat gun to warm panels before application. Problem solved.

Mistake 4: Not leaving expansion space around windows

What I did: Insulated tight up against window frames with rigid PIR and expanding foam.

Result: Windows got hot in summer sun, expanded, and cracked one seal. Small leak.

Cost: £95 for professional resealing.

Why it failed: Materials expand and contract with temperature. Rigid foam doesn’t allow movement.

The fix: Left 5-10mm expansion gap around windows. Filled with flexible sealant (Sikaflex), not rigid foam.

Mistake 5: Ignoring thermal bridging

What I did: Filled all cavities but didn’t think about metal ribs conducting cold.

Result: Cold spots on ceiling directly under ribs. Condensation formed here first.

Cost: No direct cost but annoying and inefficient.

Why it failed: Metal ribs conduct cold directly through, bypassing insulation.

The fix: Accepted some thermal bridging is inevitable. Added battens over insulation to create thermal break. Used thicker insulation where possible.

Mistake 6: Using incorrect expanding foam

What I did: Used cheap single-component foam from Pound Shop.

Result: Expanded so much it bowed my roof panels outward. Looked terrible. Also shrunk back after a few months leaving gaps.

Cost: £25 in wasted foam. Time to scrape it out.

Why it failed: Low-quality foam expands unpredictably and doesn’t stay stable.

The fix: Used Soudal Gap Filler (two-component) or Sika Boom (more expensive but excellent). Apply in layers, not huge blobs.

Mistake 7: Forgetting about cable access

What I did: Insulated everywhere, then realized I needed to run cables through insulated areas.

Result: Had to cut channels through insulation, making a mess and reducing effectiveness.

Cost: Time and frustration.

Why it failed: Didn’t think ahead about electrical layout.

The fix: Plan cable routes BEFORE insulating. Leave channels or conduit for cables.

Dealing With Condensation (The Real Enemy)

Condensation is what makes or breaks a van conversion. It’s not dramatic like a leak, but it’s relentless and destructive.

Why condensation happens:

Warm air holds more moisture than cold air. When warm, moist air touches cold metal, it cools rapidly and can’t hold the moisture anymore. The moisture condenses into water droplets.

In a van:

  • You breathe out moisture (about 1L per person overnight)
  • Cooking generates moisture
  • Wet clothes generate moisture
  • Even just existing generates moisture

Without proper insulation and ventilation, this moisture condenses on cold surfaces (windows, roof, walls) and causes problems:

  • Mould growth
  • Rust
  • Damp smell
  • Damaged furniture and fabrics
  • Health issues

The three-part solution:

1. Insulation (prevent cold surfaces)

This is what we’ve been discussing. Proper insulation keeps interior surfaces above dew point, preventing condensation.

My results with proper insulation:

  • Winter night at 5°C outside, 18°C inside: Interior roof temperature is 15-16°C
  • Windows still condense (single glazing, can’t be avoided)
  • Walls and roof stay dry

2. Ventilation (remove moist air)

Essential:

  • Roof vent (Fiamma, Maxxair, or Fantastic Fan) — Run on low overnight
  • Low-level vents (door vents or similar) — Allow fresh air in

How it works: Fresh air enters low down, warms up, picks up moisture, rises, exits through roof vent. Constant air circulation.

My setup:

  • Fiamma Turbo-Vent on roof (runs on low all night, 12V)
  • Two low-level vents in rear doors
  • Crack a window slightly if I’m cooking

3. Moisture management (reduce moisture)

Practical steps:

  • Don’t dry clothes inside (or accept you’ll get condensation)
  • Cook with lids on pans (reduces steam)
  • Wipe windows in morning (takes 30 seconds)
  • Use moisture traps in storage areas (£2-£3 each)
  • Air the van during the day when possible

When condensation is still a problem:

Even with all this, you’ll get some condensation on windows (single glazing) and in very humid conditions. This is normal.

Not normal:

  • Condensation on walls or ceiling
  • Water running down windows in sheets
  • Persistent mould growth
  • Damp smell that won’t go away

If you have these problems, your insulation or ventilation is inadequate.

Seasonal Performance: What to Actually Expect

I’ve used my current van (properly insulated) for nearly a year. Here’s the reality by season.

Winter (December-February)

Conditions tested:

  • Scottish Highlands: -5°C to +2°C
  • Lake District: -2°C to +5°C
  • Wales: 0°C to +8°C

Inside temperature without heating:

  • Overnight: 8-12°C (typically 10-12°C warmer than outside)
  • After sleeping (two people): 12-15°C (body heat warms it)

With diesel heater:

  • Reaches 18°C from 2°C in about 20 minutes
  • Maintains 18°C using 0.15-0.2L fuel per hour
  • Stays comfortable overnight on low setting

Condensation:

  • Windows: Moderate condensation (expected)
  • Walls/ceiling: Dry (no condensation)
  • Floor: Stays dry

Morning routine:

  • Wipe windows (30 seconds)
  • Open roof vent fully for 10 minutes while making coffee
  • Done

Verdict: With proper insulation and heating, UK winter is comfortable. Not like a house, but perfectly liveable.

Spring/Autumn (March-May, September-November)

Conditions:

  • Temperatures: 8-18°C
  • Mix of rain, sun, wind

Inside temperature without heating:

  • Stays within 3-5°C of outside temperature
  • Warm enough most nights without heating
  • Heat rise from cooking usually enough

Condensation:

  • Minimal (only if cooking without ventilation)
  • Windows get slight condensation overnight if temperature drops suddenly

Verdict: Perfect. Rarely need heating. Rarely too hot. These are the best months for UK vanlife.

Summer (June-August)

Conditions tested:

  • Cornwall: 22-28°C
  • South England: 24-30°C
  • One heatwave in France: 35°C (absolute hell)

Inside temperature:

  • In shade: 4-8°C cooler than outside
  • In sun: Gets hot (obviously)

Keeping cool:

  • Park in shade (critical)
  • Open all windows and roof vent (create airflow)
  • Reflectix window covers (actually useful here — blocks radiant heat)
  • Spend time outside (van is for sleeping and cooking only)

The France heatwave:

  • 35°C outside
  • Inside peaked at 32°C even in shade with windows open
  • Utterly miserable
  • We found a stream and stood in it

Verdict: Insulation helps by keeping heat out, but in serious heat (30°C+), nothing short of air conditioning makes a van comfortable. Fortunately, UK doesn’t often hit these temperatures.

Cost Summary: Three Budget Levels

Budget Option (£250-£350)

Soundproofing:

  • Skip soundproofing or use budget eBay mats: £0-£80

Insulation:

  • 25mm PIR throughout (roof, walls, floor): £180-£240
  • Expanding foam: £30
  • Vapor barrier (cheap bubble foil): £20

Battening:

  • Basic timber: £35

Total: £265-£405

Performance: Acceptable. Better than nothing. Will be cold in serious winter but liveable with good heating.

Standard Option (£450-£650) — What I recommend

Soundproofing:

  • Silent Coat or equivalent (70% coverage): £180-£280

Insulation:

  • 50mm PIR roof: £165
  • 25mm PIR walls: £95
  • 25mm PIR floor: £50
  • Expanding foam (quality): £42
  • Reflectix vapor barrier: £48

Battening:

  • Treated timber: £55

Total: £635-£735

Performance: Excellent. Comfortable year-round with appropriate heating/cooling. Minimal condensation with proper ventilation.

Premium Option (£900-£1,200)

Soundproofing:

  • Dynamat (80% coverage): £320-£400

Insulation:

  • 50mm PIR roof: £165
  • 25mm PIR walls: £95
  • 50mm PIR floor: £95
  • Sheep’s wool for curves and gaps: £85
  • Expanding foam (premium): £55
  • Reflectix vapor barrier: £48

Battening:

  • Premium treated timber: £65

Additional:

  • Professional consultation: £150-£200

Total: £1,078-£1,308

Performance: As good as it gets without spray foam. Professional-level results.

Tools You’ll Need

Essential:

  • Sharp knife or insulation saw (£8-£25)
  • Measuring tape (£5-£12)
  • Marker pen (£2)
  • Heat gun (for soundproofing) (£15-£45)
  • Roller (for soundproofing) (£5-£8)
  • Safety glasses (£3-£8)
  • Dust mask (£2-£5)
  • Work gloves (£4-£10)

Useful:

  • Cordless drill (for battening) (£60-£150)
  • Panel wipe or isopropyl alcohol (£5-£12)
  • Staple gun (for vapor barrier) (£15-£35)
  • Aluminum tape (for sealing vapor barrier) (£6-£12)

Total if buying everything: £130-£342 (depending on quality)

My Final Recommendations

After four van builds, here’s what I’d do if I started again tomorrow on a medium wheelbase van:

Day 1-2: Soundproofing

  • Silent Coat: 70% coverage focusing on floor, wheel arches, roof
  • Cost: £225

Day 3-5: Insulation

  • 50mm Celotex on roof
  • 25mm Celotex on walls
  • 25mm Celotex on floor
  • Wool insulation in curves where PIR doesn’t fit
  • Expanding foam around all edges
  • Reflectix vapor barrier over everything
  • Cost: £435

Day 6: Battening

  • 25mm x 50mm treated timber battens
  • Cost: £55

Total cost: £715 Total time: 6 days working alone

Performance: Excellent thermal insulation, good sound dampening, minimal condensation, comfortable year-round.

This is the sweet spot between cost, performance, and DIY-ability.

Final Thoughts

Insulation isn’t glamorous. Nobody’s instagramming photos of PIR boards. But it’s the foundation of everything else in your conversion.

I’ve been in £30,000 conversions with beautiful interiors that were freezing in winter because they skimped on insulation. I’ve been in tatty old vans with basic furniture that were cosy and comfortable because insulation was done properly.

Spend the money here. Spend the time here. Get it right.

Your future self — shivering in Scotland or melting in Cornwall — will thank you.

And if you cock it up the first time like I did, don’t feel bad. Learn from it, fix it, and move on. That’s what I did.

Now stop reading and go insulate your van. Properly this time.

Got questions? steve@theferalway.com — I actually respond.

Continue Reading
By
Van Conversion

Complete Campervan Conversion Guide UK

No Comments

I’ve converted four campervans. The first was an absolute disaster that cost me £2,400 in mistakes I had to rip out and redo. The second was better, but I still discovered fundamental problems six months in that required tearing half of it apart. The third? Finally got it right. Mostly.

And that’s the thing about van conversions — everyone makes it look easy on YouTube. Quick timelapse, some upbeat music, couple of weekends, and boom, you’ve got a rolling home that looks like it belongs in Architectural Digest. What they don’t show is the three weeks you spent ripping out dodgy wiring because you didn’t use proper fuses, the insulation that’s now growing mould because you forgot vapour barriers, or the £600 leisure battery that died after four months because you cheaped out on the charging system.

This guide is everything I wish someone had told me before I started. No Instagram-perfect rubbish. No glossing over the difficult bits. Just the reality of converting a van in the UK, what it actually costs when you add up all the bits you forgot to budget for, and how to avoid the expensive cock-ups I made so you can make your own unique mistakes instead.

I’m not going to tell you this is easy. It’s not. But it’s definitely doable, even if you’re not particularly handy. I’d definitely never installed insulation or built furniture. You learn as you go. You just need to be prepared for the learning curve to be expensive.

Table of Contents

  1. Is Converting a Van Actually Worth It?
  2. Choosing Your Base Van: What Actually Matters
  3. Legal Stuff (Boring But Important)
  4. Planning Your Layout
  5. Essential Tools & Workshop Space
  6. The Complete Build Process (Step-by-Step)
    • Strip Out
    • Rust Treatment & Soundproofing
    • Insulation (The Most Important Decision)
    • Electrical Systems (12V & 240V)
    • Plumbing & Water Systems
    • Gas Systems & Heating
    • Building the Furniture
    • Wall & Ceiling Lining
    • Flooring
    • Windows & Ventilation
    • Final Touches
  7. Realistic Cost Breakdown (Three Budget Levels)
  8. Living With Your Conversion
  9. Common Problems & Solutions
  10. What I’d Do Differently

Is Converting a Van Actually Worth It?

Let me be straight with you. A basic campervan conversion will cost £3,000-£8,000 if you do it yourself on a tight budget, £8,000-£15,000 for a decent quality DIY build, or £15,000-£35,000+ if you pay someone else. That’s a lot of money for something that’ll leak occasionally, creak constantly, and drive you mental at least once a month.

I’ve spent about £38,000 across three vans (including purchasing the vans themselves). My current setup is worth maybe £22,000 if I sold it tomorrow. So I’m £16,000 down on paper. Not exactly a sound financial investment.

But here’s why I keep doing it: freedom. Proper freedom. Not the Instagram marketing version where everything’s sunrise yoga and perfect coffee shots. The kind where you can park up in the Cairngorms for a week, work from a layby with a sea view, or bugger off to Wales on a Friday afternoon without booking anything or spending £150 a night on accommodation.

I’ve slept in 43 different locations this year. I’ve worked from Scottish beaches, Welsh mountains, and Cornwall car parks. I’ve spent maybe £800 on campsites total because most of the time I’m wild camping legally (which I’ll cover later). Try doing that in hotels.

You should convert a van if:

  • You actually want to use it regularly (minimum 30-40 nights a year to justify the hassle)
  • You’re prepared to fix things yourself at 11pm in a layby
  • You can live with compromises — limited space, basic amenities, no shower (unless you add one)
  • You have realistic expectations about wild camping in the UK (it’s not as easy as Scotland makes it look)
  • You enjoy the process of building things (because if you don’t, you’ll hate every minute)
  • You’re happy maintaining something ongoing (this isn’t fit and forget)

Don’t bother if:

  • You want hotel comfort on wheels
  • You’re not handy with basic DIY (or willing to learn)
  • You need everything to be perfect and finished
  • Your budget is already maxed out (it always costs more than planned)
  • You’re doing it because it looks cool on social media
  • You get stressed by things breaking or not working

The third point is crucial. I’ve met so many people who’ve spent £20,000 on a conversion, used it twice, and sold it at a massive loss because they couldn’t handle the reality. A van is not a house. It’s not even a caravan. It’s a compromise that gives you mobility in exchange for comfort.

Choosing Your Base Van: What Actually Matters

This is where most people overthink it. I’ve driven Transit Customs, Sprinters, Transporters, Vivaros, Trafics, Crafters, and a Fiat Ducato that I still have nightmares about. They’ve all got pros and cons. None of them are perfect.

The Realistic UK Options

VW Transporter (T5/T6/T6.1)

  • Price: £8,000-£30,000 depending on age/mileage
  • Engine: 2.0 TDI (102bhp, 140bhp, 150bhp, 199bhp variants)
  • Size: 4.9-5.3m long, 1.9m wide, 1.99m high (standard roof)
  • Best for: Stealth camping, city parking, fuel economy (35-40mpg)
  • Reality check: Everyone wants one, so you’re paying the VW tax. A 2015 Transporter costs the same as a 2018 Transit Custom. Parts aren’t cheap either — an alternator is £280 vs £140 for a Transit. Service costs are higher. But they hold value better and the driving experience is nicer.

I nearly bought a T5.1 in 2019. Test drove three. All had DMF (dual mass flywheel) issues that would’ve cost £1,200-£1,500 to fix. Walked away from all of them. If you’re buying a Transporter, budget £1,000-£2,000 for immediate repairs unless you’re getting a pristine example.

Mercedes Sprinter (2006-2018 models)

  • Price: £6,000-£25,000
  • Engine: 2.1 CDI (various outputs) or 2.2 CDI
  • Size: Multiple lengths — SWB 5.9m, MWB 6.9m, LWB 7.4m
  • Best for: Standing height, long trips, full-time living
  • Reality check: Big. Properly big. The MWB won’t fit in most car parks. You’ll struggle in narrow UK lanes, historic town centres, and anywhere with width restrictions. But if you want a shower, toilet, and proper kitchen, this is your van.

I drove one for six months. Loved the space. Hated parking in literally every UK town. Got stuck in a Lake District village and had to reverse 200 metres with tourists watching. Would I buy another? Only if I get to going full-time.

Ford Transit Custom (2012-present)

  • Price: £7,000-£22,000
  • Engine: 2.0 TDCi (various outputs: 105, 130, 170bhp)
  • Size: SWB 4.97m or LWB 5.34m, 2.06m wide, various heights
  • Best for: Middle ground between size and practicality
  • Reality check: Reliable, common parts (clutch £280, alternator £140), good fuel economy (38-42mpg), easy to drive. Not as trendy as VW which means better value. This is what I’d buy again.

My current van is a 2017 Transit Custom, medium wheelbase, medium roof (allows standing if you’re under 6ft). Paid £12,400 with 78,000 miles. It’s had one fault in 30,000 miles — a DPF sensor that cost £80 to replace.

Renault Trafic/Vauxhall Vivaro/Nissan Primastar (same van, different badges)

  • Price: £5,000-£15,000
  • Engine: 2.0 dCi or 1.6 dCi
  • Size: Similar to Transit Custom
  • Best for: Budget conversions where you want decent size
  • Reality check: Often ex-fleet vans with high mileage. They’re cheaper for a reason — quality isn’t quite Transit or VW level. But they’re fine if you’re not fussy. Check the service history properly because fleet vans get thrashed.

Fiat Ducato/Peugeot Boxer/Citroën Relay (another badge-shared family)

  • Price: £5,000-£18,000
  • Engine: 2.3 JTD or 2.0 BlueHDi
  • Size: Massive range of sizes available
  • Best for: Standing height on a budget (higher roofs than most)
  • Reality check: Popular with professional converters because of the size options. Driving experience isn’t great — feels cheap and plasticky. But you get a lot of van for the money.

What I’d Actually Buy Today

If I was starting fresh with a £12,000 budget for the van itself:

Option 1: £11,000-£13,000 — Ford Transit Custom (2016-2018)

  • Medium wheelbase (5.34m)
  • Medium roof (1.78m internal height)
  • 130bhp diesel
  • Under 100,000 miles
  • Full service history (non-negotiable)
  • Ideally with bulkhead already fitted

Why? Parts are everywhere. Every mechanic can work on them. Insurance is reasonable. Good fuel economy. And you can actually stand up inside with medium roof if you’re under 6ft tall.

Option 2: £10,000-£12,000 — VW Transporter T5.1 (2010-2015)

  • Standard wheelbase
  • Standard roof (you won’t stand up, but that’s fine)
  • 140bhp diesel
  • Under 120,000 miles
  • Cambelt and water pump already done (or budget £800 for it)
  • Check the DMF — listen for rattling when starting

Why? Better driving experience. Better fuel economy (40mpg vs 38mpg). Easier to park. Cooler looking (if you care). But you’re paying £2,000 more for an older van with more miles.

I went with the Transit. No regrets.

Critical Checks Before Buying ANY Van

I’ve looked at 27 vans across my three conversions. Here’s what I check every time:

1. Service History (Absolutely Critical) Full service history or walk away. I don’t care how shiny it looks. No history means you’re buying problems.

What I’m looking for:

  • Services at correct intervals (not “I do it myself, mate”)
  • Cambelt changes on schedule (usually 5 years or 100k miles)
  • Major work receipts (turbo, injectors, DPF, DMF)

2. Rust Inspection (Get Underneath) Bring a torch. Get under the van. Check:

  • Chassis rails (especially near rear axle)
  • Floor panels around sliding door runners
  • Inside the fuel filler cap area
  • Wheel arches and sills

Surface rust is fine. Holes or flaky rust that comes away in chunks? Walk away unless you’re prepared to deal with it.

3. Mechanical Tests

  • Start from cold — does it rattle? (DMF issue)
  • Does it smoke on startup? (injectors or turbo)
  • Check the oil — milky colour means head gasket problems
  • Test the heater on full blast for 10 minutes (heater replacement is £400-£800)
  • Check for DPF warning lights

4. Payload Capacity This is huge and everyone ignores it. Your van has a gross vehicle weight (GVW). Subtract the unladen weight. That’s your payload.

My Transit Custom has 1,050kg payload. Sounds like loads. But:

  • Furniture and insulation: 250kg
  • Electrical system and batteries: 80kg
  • Water (40L full): 40kg
  • Two people: 160kg
  • Clothes, food, gear: 100kg
  • Bikes on a rack: 40kg

Total: 670kg. I’m fine. But I’ve seen people overload vans by 300kg+ and not realise until they get pulled by DVSA.

5. The “Does It Have a Bulkhead?” Question You’ll need one for insurance. If it doesn’t have one, add £250-£400 to your budget. Some people try to argue that a plywood one is fine. Some insurers accept it. Some don’t. I wouldn’t risk it.

6. Windows Buying a van with windows already fitted saves you £500-£1,200 and a lot of stress. Cutting holes in a van is nerve-wracking.

Legal Stuff (Boring But Actually Important)

Right. Before you rip out the interior and start Instagramming your progress, understand this: the DVLA doesn’t care about your Pinterest board. They care about weight, windows, and whether you’re taking the piss with the classification.

DVLA Motor Caravan Reclassification

If you want your van to be a “Motor Caravan” on the V5C (which helps with insurance costs, some parking restrictions, and speed limits on single carriageways), you need to meet specific criteria.

The actual requirements:

  1. Fixed furniture for sleeping — A bed. Not a mattress on the floor. Actual fixed or fold-down bed frame.
  2. Fixed furniture for cooking — A hob (even a single burner) and worktop. Built in, not just a camping stove balanced on a box.
  3. Fixed furniture for storage — Cupboards or drawers that are secured to the van.
  4. Seating — The cab seats count, but you should have additional seating in the living area.
  5. A table — Can be removable but must be there. Size matters — apparently. More on this in a minute.
  6. Windows — At least one on each side of the van (not including cab doors). Roof windows count.

The process:

Fill in a V5C application form, include photos showing:

  • The bed (from multiple angles)
  • The cooking area with hob
  • The seating area with table
  • The storage
  • External shots showing windows
  • Vehicle weight plate

Then wait. And wait. Processing time is currently 6-8 weeks.

My experiences:

Conversion 1 (2019): Approved after 5 weeks. No issues.

Conversion 2 (2021): Rejected initially. They said my table was “too small”. It was 40cm x 60cm. I wrote back pointing out that’s bigger than most airline tray tables and larger than the tables in many motorhomes. They approved it on appeal after another 4 weeks.

Conversion 3 (2023): Requested an inspection. Inspector came, spent 10 minutes looking around, approved it. Got the V5C back 3 weeks later.

Top tip: Include photos of EVERYTHING. The more comprehensive your submission, the less likely they are to reject it or request an inspection.

Insurance for Converted Vans

Get insurance quotes BEFORE you buy the van. Seriously. Some insurers won’t touch self-conversions. Others charge double for under-25s or drivers with less than 2 years’ experience.

Good UK insurers for self-conversions:

  • Comfort Insurance — Best rates I’ve found, cover self-builds up to £15,000 conversion value
  • Safeguard — Slightly more expensive but very flexible on modifications
  • Adrian Flux — Specialist knowledge, good for unusual builds
  • A-Plan — Decent rates for over-30s with clean licences
  • Caravan Guard — Good if you’re using it like a motorhome (occasional use)

What affects your premium:

  • Your age (under 25 = significantly more expensive)
  • Where you live (city centre vs rural)
  • Conversion value (declare honestly — they WILL check after a claim)
  • How you’ll use it (full-time living vs weekend trips)
  • Security (alarms, trackers, steering locks reduce premiums)
  • Driving history (obvious)

My premiums:

  • Age 28, living in Bristol: £780/year
  • Age 31, living in rural Wales: £420/year (same van, same driver)

Location makes a massive difference.

Critical: Declare EVERYTHING. Undeclared modifications = no payout. I’ve seen someone lose a £18,000 claim because they didn’t declare their solar panels.

MOT Considerations for Conversions

Your van needs an MOT. If you’ve added weight, check you’re not over the manufacturer’s GVW (it’s on a plate inside the door jamb or in the manual).

Things that fail MOTs on conversions:

Gas systems without proper ventilation:

  • High-level vents required (above the cooker)
  • Low-level vents required (for heavier-than-air gas leaks)
  • Drop-out holes in floor if you have an underslung LPG tank

Electrical work that looks dodgy:

  • Exposed wires (everything must be sheathed or in conduit)
  • No fusing (everything must be properly fused)
  • Battery not secured (it can’t move if you crash)
  • Wiring running across sharp metal edges

Weight distribution issues:

  • Can’t be obviously tail-heavy or nose-heavy
  • Suspension can’t be overloaded (rear sagging badly)

Non-secured items:

  • Furniture must be fixed (it can’t become a projectile)
  • Gas bottles must be secured properly
  • Loose items that could hit the examiner aren’t ideal

My approach: Get a pre-MOT check before you book the real thing. Costs £30-£40 and saves you the hassle of a fail. I use a local garage that’s done loads of conversions. They know what they’re looking for.

Speed Limits (Actually Matters)

Panel van (N1 classification):

  • 70mph on motorways
  • 60mph on dual carriageways
  • 50mph on single carriageways

Motor caravan (M1 classification):

  • 70mph on motorways
  • 70mph on dual carriageways
  • 60mph on single carriageways

That 10mph difference on dual carriageways actually matters on long trips.

Wild Camping Legal Status

Scotland: Legal under the Scottish Outdoor Access Code. You can camp pretty much anywhere as long as you’re respectful. This is brilliant.

England and Wales: NOT legal without landowner permission. But enforcement is patchy. If you’re discreet, don’t take the piss, and move on when asked, you’ll mostly be fine.

What “discreet” means:

  • Not parking directly on the beach or in obvious beauty spots
  • Arriving late, leaving early
  • No BBQs, no generators, no awnings
  • Taking your rubbish with you
  • Not staying multiple nights in the same spot

I’ve wild camped 200+ nights in England and Wales. Been moved on twice. Both times were fine — just “Sorry, you can’t stay here, there’s a campsite 3 miles up the road.” No drama.

Planning Your Layout: Getting This Right Matters

I’ve seen people spend hours debating whether to put a shower in a van that’s 1.8 metres wide. Let’s be realistic about what you actually need and what actually works in a small space.

Understanding Your Space

A medium wheelbase Transit Custom has about 7.5 cubic metres of usable space. That sounds like loads until you start putting things in it.

My current van:

  • Length (cargo area): 2.6m
  • Width (internal): 1.7m
  • Height (internal): 1.75m

That means:

  • My bed takes up 1.9m x 1.4m = 40% of floor space
  • Kitchen area: 0.8m x 0.6m = another 10%
  • Storage and seating: the rest

The Essential Zones (In Order of Priority)

1. Sleeping Area

You need to sleep properly. A bad bed ruins everything. I tried sleeping on a 1.1m wide bed for three months in my first conversion. My back still hasn’t forgiven me, and my relationship nearly didn’t survive.

Minimum dimensions:

  • Single: 1.9m x 1.2m (I wouldn’t go narrower)
  • Small double: 1.9m x 1.4m (comfortable for two)
  • Proper double: 1.9m x 1.6m (requires LWB van)

Bed types:

Fixed bed (what I use):

  • Pros: Always ready, comfortable, storage underneath
  • Cons: Takes up permanent space, limits flexibility
  • Cost: £150-£300 in materials

Rock and roll bed:

  • Pros: Doubles as seating, quick conversion
  • Cons: Expensive (£1,200-£2,500), not as comfortable, limits rear access
  • Cost: £1,200-£2,500 for a decent one

DIY slat bed:

  • Pros: Cheap, simple, comfortable with right mattress
  • Cons: Takes up permanent space
  • Cost: £100-£200
  • This is what I built. 18mm ply base, 47mm x 75mm timber frame, slats across the top, 4-inch memory foam mattress on top.

2. Cooking Zone

You need a hob and a worktop. That’s it. You don’t need a four-ring cooker, an oven, and a grill. This isn’t MasterChef. I cook excellent meals on a two-burner setup.

What works:

  • Two-burner gas hob (£60-£120) or
  • Single induction hob if you have shore power or massive battery (£40-£80) or
  • Portable diesel cooker like Webasto/Wallas (£800-£1,400 — only worth it for full-time)

Worktop size:

  • Minimum: 60cm x 40cm (barely enough)
  • Better: 80cm x 50cm (comfortable for meal prep)

I use a 90cm x 45cm worktop made from 28mm beech kitchen worktop from B&Q (£38). It’s got a two-burner gas hob on one side, prep space in the middle, and a washing up bowl that fits in a cutout on the other side.

3. Storage (You Need More Than You Think)

I massively underestimated storage on my first conversion. You need space for:

Clothes:

  • 7 days of clothes for two people = surprising amount
  • Jackets and waterproofs (bulky)
  • Spare shoes and boots

Food:

  • Dry goods (pasta, rice, tins)
  • Snacks (you’ll have loads)
  • Herbs and spices (if you actually cook)

Cooking equipment:

  • Pans, pots, kettle
  • Plates, bowls, mugs
  • Cutlery and utensils

Outdoor gear:

  • Walking boots
  • Camping chairs
  • Beach stuff or climbing gear or whatever you do

Tools:

  • Basic toolkit (you’ll need it)
  • Spare fuses and electrical bits
  • Duck tape and cable ties (always)

My storage setup:

  • Overhead cupboards above bed: 1.8m x 0.4m x 0.3m deep
  • Underbed storage: Divided into sections with plastic boxes
  • Kitchen cupboard: 0.8m x 0.5m x 0.5m deep
  • Under-worktop drawer: For utensils and smaller items

4. Seating

Somewhere to sit that isn’t your bed. I built an L-shaped bench seat that doubles as storage. Dimensions: 0.8m x 0.4m along one side, 0.6m x 0.4m along the back.

Added cushions on top (£65 from eBay — just cheap sofa cushions cut to size). Works fine.

5. Fridge (Essential if You Use the Van Regularly)

I didn’t have a fridge in conversion #1. Used a coolbox with ice packs. It was rubbish. Melted ice everywhere, food going off, constant hassle.

Bought a 15L compressor fridge (Alpicool C15) for £160. Life-changing. Genuinely. Fresh milk, cheese that doesn’t spoil, cold beer.

6. Wet Room/Toilet (Optional — Skip It Unless Full-Time)

Unless you’re living full-time, skip the shower. Public toilets, campsites, gym memberships, and wild swimming work fine. The space cost isn’t worth it for weekend trips.

I use a portable Thetford toilet (£65) that lives under the bed in a sealed box. Used it maybe six times in two years. But when you need it at 3am in a layby, it’s worth having.

Common Layout Mistakes

Mistake 1: Too much fixed furniture

My first van had built-in units everywhere. Looked great in photos. Completely impractical in reality. Couldn’t fit bikes inside. Couldn’t reorganise when I needed to carry something big. Couldn’t adapt the space for different trips.

Now: Modular. My bed can come out in 20 minutes (four bolts). My seating can be removed if needed. Fixed what must be fixed (kitchen), removable everything else.

Mistake 2: No headroom where it matters

I couldn’t stand up at my cooking area in van #2. Spent six months hunched over like Quasimodo cooking pasta. Put standing height where you’ll actually stand — which is usually the kitchen area, not the bed.

Mistake 3: Blocking windows with furniture

Don’t cover windows with units. You’ll want the light. You’ll want the ventilation. And it looks weird from outside (screams “someone’s living in there”).

Mistake 4: Not thinking about door access

I built beautiful overhead storage in van #1. Then realised I couldn’t open the sliding door fully because the storage was in the way. Had to cut 15cm off the unit. Idiot.

Mistake 5: Underestimating how much you move around

In a small space, you bump into things. A lot. Sharp corners on furniture will destroy your shins. Round them off. Seriously.

Layout Examples That Work

The Weekend Warrior:

  • Fixed bed across the back (1.9m x 1.4m)
  • Kitchen along one side (0.9m long)
  • Seating opposite kitchen
  • Storage underneath and overhead
  • Total space: 2.6m long x 1.7m wide

The Full-Timer:

  • Fixed bed across back with garage underneath for bikes
  • Galley kitchen along one side (1.2m)
  • Wet room (0.8m x 0.8m) — only if you must
  • Seating/dinette area
  • Requires LWB van minimum

The Stealth Setup:

  • Side-to-side bed that can fold up
  • Minimal overhead storage (keeps profile low)
  • All windows covered with blackout material
  • Kitchen hidden behind panels
  • Looks like a work van from outside

Essential Tools & Workshop Space

You don’t need a fully-equipped workshop, but you do need some basics.

Must-have tools (you’ll use these constantly):

  • Cordless drill (£60-£150) — Makita or DeWalt, don’t cheap out
  • Jigsaw (£40-£100)
  • Circular saw (£60-£120)
  • Orbital sander (£40-£80)
  • Screwdriver set (£15-£30)
  • Socket set (£25-£60)
  • Adjustable spanner set (£20)
  • Wire strippers and crimpers (£15-£40)
  • Multimeter (£15-£40)
  • Measuring tape and spirit level (£15)
  • Clamps (6+ of various sizes, £30-£60)

Total if buying everything new: £400-£800

I already had tools from the work i do.

Useful but not essential:

  • Angle grinder (for cutting metal)
  • Rivet gun (for securing some panels)
  • Heat gun (for vinyl wrapping or shrinking heat shrink)
  • Workbench (makes everything easier)

Workshop space:

I did my first conversion on my driveway. It was December. It was horrible. Rain delays. Frozen fingers. Neighbours complaining.

Second conversion: Borrowed a friend’s garage. Much better.

Third conversion: Rented a unit for £250/month for 6 weeks. Best decision. Warm, dry, space to spread out, secure storage for tools overnight.

If you can rent a space or borrow a garage, do it. Working outside in British weather is miserable.

The Complete Build Process: Step-by-Step

Right. This is the detailed bit. I’m going to walk you through every step of a conversion the way I do it now, with all the mistakes to avoid and techniques I’ve learned.

Step 1: Strip Out the Interior (1-3 days)

Everything comes out. Every panel, every bit of plyboard lining, every metal shelf bracket, every stud. You want bare metal because you need to see what you’re working with.

Tools needed:

  • Screwdrivers (Phillips, flathead, Torx set)
  • Socket set with extension bars
  • Drill with metal cutting bits
  • Angle grinder (if there’s welded shelving — likely in ex-fleet vans)
  • Pry bar or crowbar
  • Safety glasses and work gloves
  • Dust masks (seriously — the dust is horrible)

The process:

Day 1: Remove loose items and panels Start with anything that’s obviously detachable. Most panel vans have ply lining held in with plastic clips or screws. Remove carefully if you want to reuse them (I usually don’t — they’re often damaged or smelly).

Day 2: Remove fixed metal shelving Ex-fleet vans often have metal shelving bolted or welded to the chassis. Bolted stuff: unbolt it. Welded stuff: angle grinder time. Wear a face shield. Sparks everywhere.

Day 3: Deep clean Sweep out all the dust and debris. Then pressure wash if you can (I use a friend’s driveway for this). Let it dry completely (2-3 days in summer, a week in winter).

Cost: £0 if you have tools, £80-£150 if you need to buy them

What I learned:

  • Some vans have underseal that’s deteriorating and flaking. Strip as much as you can now.
  • Take photos of where panels attach and how wiring is routed. You’ll forget.
  • Label everything if you’re keeping any original parts.

Step 2: Rust Treatment & Soundproofing (2-4 days)

This is the foundation. Screw this up and you’ll have problems for years.

Rust inspection and treatment:

Check every inch of the floor, wheel arches, door sills, and around window apertures for rust. Use a torch and get underneath.

What you’ll find:

  • Surface rust (orange, powdery): Fine, treat it
  • Flaking rust (comes off in chunks): More serious, needs grinding back
  • Holes: You need to cut out and weld in new metal, or use fibreglass patches

Treatment process:

  1. Wire brush or grind off loose rust (angle grinder with wire brush attachment)
  2. Apply rust converter (Hammerite Kurust or similar, £8 per 250ml)
    • Brush it on liberally
    • Let it cure (24 hours minimum)
    • It converts rust to a stable surface
  3. Prime with rust-resistant primer (£12 per litre)
  4. Top coat with chassis paint (£15-£25 per litre)

I found rust around the fuel filler and on the floor near the sliding door runners. Spent two full days grinding, treating, and repainting. Total materials: £65.

Soundproofing:

This is the difference between a rattly tin can and something you can actually have conversations in.

Materials:

  • Silent Coat (£180-£250 for a full van kit) — This is what I use
  • Dynamat (£250-£400) — More expensive but slightly better
  • Budget option: Closed-cell foam with adhesive backing (£80-£120) — Worse but better than nothing

Application:

  1. Clean all metal surfaces with panel wipe or isopropyl alcohol
  2. Cut soundproofing to fit each panel (I make cardboard templates first)
  3. Peel and stick, then roll firmly with a roller to remove air bubbles
  4. Focus on:
    • Entire floor
    • Wheel arches
    • Roof (at least 50% coverage)
    • Door panels
    • Behind cab seats

Takes 2-3 days to do properly. I covered about 70% of the interior in my current van.

Cost: £200-£400 total for rust treatment and soundproofing

What I learned:

  • Don’t skip the soundproofing. Every single person I know who skipped it regrets it.
  • You can’t apply soundproofing in cold weather — it won’t stick properly. Needs to be above 15°C.
  • Heat the panels slightly with a heat gun to improve adhesion.

Step 3: Insulation (3-5 days) — THE MOST IMPORTANT DECISION

Get this wrong and you’ll be cold in winter, hot in summer, and dealing with condensation year-round. I’ve insulated four vans (one twice after I cocked it up). Here’s what actually works in the UK.

Understanding R-values and thermal bridging:

R-value measures thermal resistance. Higher = better insulation. But it’s not just about R-value — you also need to prevent thermal bridging (where metal ribs conduct cold through to the interior).

Insulation options in detail:

Celotex/Kingspan (PIR Boards) — What I use

  • Cost: £4-£8 per square metre
  • R-value: Excellent (0.022 W/mK)
  • Thicknesses available: 25mm, 50mm, 75mm, 100mm
  • Pros: Best thermal performance for thickness, moisture resistant, easy to cut, fairly rigid
  • Cons: Can’t compress into curves, creates air gaps that must be filled, not eco-friendly

Where I use it:

  • 50mm on the roof (between the metal ribs)
  • 25mm on the walls (between ribs)
  • 25mm on the floor (under the subfloor)

How to install it:

  1. Measure the gaps between metal ribs (they’re usually irregular)
  2. Cut PIR board 5mm oversize for a friction fit
  3. Use expanding foam to fill gaps around edges (NOT behind the board — it’ll cause bridging)
  4. Leave 10-15mm air gap behind the board for ventilation where possible

Sheep’s Wool (Thermafleece)

  • Cost: £8-£15 per square metre
  • R-value: Good (0.038 W/mK)
  • Pros: Breathable (handles moisture really well), eco-friendly, compresses into awkward spaces, natural, doesn’t require vapour barriers
  • Cons: More expensive, harder to work with, needs treating against moths (comes pre-treated usually), harder to source

I used this in van #2 for the walls. It worked well but was more faff to install. And it’s expensive.

Reflectix/Bubble Foil

  • Cost: £2-£5 per square metre
  • R-value: Rubbish on its own (only works with air gaps)
  • Pros: Cheap, reflects radiant heat IF you have air gaps
  • Cons: Marketing is misleading, doesn’t work as primary insulation, needs 25mm air gap each side to do anything useful

Don’t use this as your main insulation. I use it as a vapour barrier over my PIR boards, but that’s it.

Spray foam (professional installation)

  • Cost: £800-£2,000 professionally done
  • Pros: Fills every gap, excellent coverage, no thermal bridging
  • Cons: Expensive, makes van panels impossible to remove later, can trap moisture if not done right, voids some van warranties

I’d only consider this for a forever van.

My actual installation process:

Roof (most important area):

  1. Measure between ribs — mine varied from 380mm to 410mm
  2. Cut 50mm Celotex to fit each section (friction fit)
  3. Use expanding foam around edges (Soudal Gap Filler, £6 per can)
  4. Cover with Reflectix as vapour barrier
  5. Batten over the top for fixing ceiling panels later

Walls:

  1. 25mm Celotex between ribs
  2. Expanding foam around edges
  3. Reflectix as vapour barrier
  4. Battens for wall lining

Floor:

  1. Treated any rust first
  2. 25mm Celotex across entire floor
  3. 12mm ply subfloor on top, screwed into original floor through the insulation
  4. This raises the floor 37mm — annoying but worth it

Critical mistakes to avoid:

Mistake 1: Not leaving air gaps for ventilation I filled every gap with insulation in van #1. Moisture couldn’t escape. Got condensation and mould after 4 months. Had to rip it all out.

You MUST have ventilation paths for air to circulate. I leave 10-15mm between the metal ribs and the insulation in most areas.

Mistake 2: Using closed-cell foam directly against metal Closed-cell foam doesn’t breathe. If you stick it directly to metal with no air gap, you trap moisture. Bad news.

Mistake 3: Not insulating the floor “Heat rises” they said. “Floor insulation doesn’t matter” they said. Wrong. Absolutely wrong. You lose loads of heat through the floor in UK winters.

Mistake 4: Over-compressing wool insulation Wool works by trapping air. Compress it too much and you reduce its effectiveness. Don’t pack it in tight.

Cost for my current van (medium wheelbase):

  • Celotex 50mm (roof): £165 (8 sheets)
  • Celotex 25mm (walls and floor): £145 (10 sheets)
  • Reflectix vapour barrier: £48 (25m roll)
  • Expanding foam: £42 (7 cans)
  • Battens for fixing: £35

Total: £435

Time taken: 4 days working alone

Results: Interior stays 5-8°C warmer than outside in winter without heating. No condensation issues. Worth every penny and every hour.

Step 4: Electrical System (3-7 days)

This is where people get scared. Don’t be. A 12V system isn’t complicated if you’re methodical and follow the rules.

Basic electrical theory you need:

  • Voltage (V): Like water pressure (12V system in your van)
  • Current (A): Like water flow (how much power is being used)
  • Watts (W): Voltage x Current (actual power consumption)
  • Amp hours (Ah): How much current your battery can supply over time

Example: A 12V LED light using 5W draws 0.42 Amps (5÷12). If you run it for 10 hours, it uses 4.2Ah from your battery.

System components explained:

1. Leisure battery (the heart of your system)

Options:

  • Lead acid (cheapest): £80-£120 for 110Ah
    • Heavy, needs ventilation, can’t discharge below 50%, lasts 2-4 years
    • Don’t bother unless broke
  • AGM (better): £150-£250 for 110Ah
    • Sealed, no maintenance, can’t discharge below 50%, lasts 3-6 years
    • Decent budget option
  • Lithium (LiFePO4) (best): £400-£700 for 100Ah
    • Light, can discharge to 100%, lasts 8-12 years, charges faster
    • This is what I use now (Fogstar Drift 105Ah, £449)

My calculations:

  • LED lights: 15W total x 4 hours = 60Wh = 5Ah
  • Phone/laptop charging: 50Wh = 4.2Ah
  • 12V fridge: 40W x 12 hours (cycling) = 480Wh = 40Ah
  • USB devices: 20Wh = 1.7Ah

Daily total: ~51Ah

A 100Ah lithium gives me two days without charging. Add solar and I’m indefinite.

2. Charging the battery

Option A: Split charge relay (basic, cheap)

  • Cost: £30-£60
  • How it works: Connects your leisure battery to your alternator when engine is running
  • Pros: Cheap, simple
  • Cons: Doesn’t charge lithium properly, inefficient, can drain starter battery

Option B: DC-DC charger (better)

  • Cost: £100-£200 (Victron Orion, Renogy, CTEK)
  • How it works: Smart charger that properly charges your leisure battery from alternator
  • Pros: Charges lithium properly, protects both batteries, efficient
  • Cons: More expensive

I use a Victron Orion 12/12-18 (£157). Charges my lithium battery properly while driving. No regrets.

Option C: Mains hookup charger

  • Cost: £60-£150
  • When you’re on a campsite with electric hookup

I have a basic CTEK MXS 5.0 (£72) for campsite stays.

3. Solar panels (optional but brilliant)

My setup:

  • 200W solar panel (£180)
  • Victron MPPT 75/15 controller (£85)
  • Roof mounting brackets (£35)
  • Cable and connectors (£30)

Performance in UK:

  • Summer: 60-80Ah per day (even on cloudy days)
  • Winter: 10-20Ah per day (better than nothing)

This keeps my fridge running and devices charged indefinitely in summer. Winter needs driving to top up.

Installation:

  1. Mounted panel to roof with brackets and Sikaflex
  2. Cable runs down through roof vent hole (added rubber grommet)
  3. MPPT controller on wall near battery
  4. Fused at battery (critical)

4. Distribution and safety

Fuse box: £40-£80 for a decent one with 6-12 circuits

EVERY circuit must be fused. Not negotiable. I use:

  • 30A for the main feed from battery
  • 10A for LED lights
  • 15A for 12V sockets
  • 20A for fridge

Wiring: Cable size matters. Too small = voltage drop and fire risk.

  • 1-5A: 1.5mm² cable
  • 5-15A: 2.5mm² cable
  • 15-25A: 4mm² cable
  • 25-40A: 6mm² cable
  • Battery to fuse box: 10mm² or larger

I bought a mixed box of cable from 12V Planet (£85).

5. Outputs

  • LED lights: £8-£15 each (I have 4 lights total — cost £45)
  • 12V socket: £5-£12 each (I have 2)
  • USB sockets: £8-£15 each (I have 2 twin USB sockets)

My complete electrical system cost:

  • Fogstar Drift 105Ah lithium battery: £449
  • Victron Orion DC-DC charger: £157
  • 200W solar panel: £180
  • Victron MPPT controller: £85
  • Fuse box and fuses: £62
  • Cable (various sizes): £85
  • LED lights: £45
  • 12V sockets: £18
  • USB sockets: £24
  • Switches and connectors: £38
  • Mounting hardware: £27

Total: £1,170

Worth noting: You can do a basic system for £400-£500 with AGM battery and no solar. But you’ll upgrade later. I did.

Installation tips:

  1. Plan your cable runs first — I drew a wiring diagram before I bought anything
  2. Label everything — Every wire, every connection
  3. Use properly crimped connectors — No twisting wires together
  4. Fuse everything — Did I mention this already?
  5. Keep battery as low in the van as possible — Weight distribution
  6. Secure battery properly — It can’t move in a crash
  7. Use cable trunking — Keeps it neat and protected

Testing:

Before you connect everything permanently:

  1. Test each circuit with multimeter
  2. Check for shorts
  3. Verify fuse ratings are correct
  4. Test under load (turn things on)

I found two wiring mistakes during testing. Much better than finding them after a fire.

Step 5: Plumbing & Water Systems (1-2 days)

I’ve tried complicated systems. They leak. They break. They freeze. Now I keep it simple.

My current setup (and why):

Fresh water:

  • 2x 10L Jerry cans (Scepter military-style, £28 each)
  • Total: 20L fresh water
  • Sits under the kitchen worktop
  • Easy to refill (just swap the can)
  • If it freezes, I can take it out

Why not a fixed tank? They’re a pain to fill, impossible to clean properly, and add weight permanently.

Pump:

  • Shurflo 12V water pump (£67)
  • Flow rate: 4L per minute
  • Pressure: 40 PSI
  • Fitted under the sink

I tried a foot pump first (£25). Hated it. The Shurflo is worth the extra money.

Tap:

  • Basic chrome mixer tap (£28 from Screwfix)
  • Connects to pump outlet
  • No hot water (I heat water in a kettle if needed)

Sink:

  • Stainless steel round sink (£42)
  • Diameter: 340mm
  • Depth: 150mm
  • Cut hole in worktop with jigsaw, sealed with silicone

Waste water:

  • 25L plastic container with lid (£18)
  • Sits under the van
  • Waste pipe goes through floor (sealed with rubber grommet)
  • Empty at campsites or public waste points

Complete installation:

  1. Cut hole in worktop for sink
  2. Fit sink with silicone sealant
  3. Connect tap to sink
  4. Drill hole through floor for waste pipe (25mm)
  5. Mount pump under worktop
  6. Connect inlet hose from Jerry can to pump
  7. Connect outlet hose from pump to tap
  8. Wire pump to fused 12V supply with switch
  9. Test for leaks (ran it for 30 minutes — found two drips, tightened jubilee clips)

Total cost:

  • Jerry cans x2: £56
  • Shurflo pump: £67
  • Tap: £28
  • Sink: £42
  • Waste container: £18
  • Hoses and fittings: £24
  • Switch: £6

Total: £241

Why I don’t have hot water:

  • Adds complexity (more things to break)
  • Adds weight (water heater + hot water)
  • Adds cost (£200-£400 for a decent system)
  • Adds power consumption

I heat water in a kettle for washing up. For showers, I use campsites or a solar shower bag (£18) in summer.

Winter considerations:

Water freezes. I’ve had pipes freeze and split. Now:

  • I empty the system if it’s below freezing
  • I take the Jerry cans inside (or drain them)
  • I added a small 12V heater near the pump (£22) that I can run overnight if needed

Step 6: Gas Systems & Heating (2-3 days + professional certification)

I don’t mess with gas installation. I’ll tell you what I have and how it works, but if you’re installing gas, pay a professional to do it or certify it.

Gas setup:

Bottle:

  • 6kg propane bottle (Calor or FloGas)
  • Lasts 3-4 weeks for cooking only
  • Lasts 1-2 weeks if using gas heating too

Storage:

  • External gas locker (£85)
  • Mounted to rear door
  • Vented to outside (drop holes in floor)
  • Secured with strap

Hob:

  • Smev 8821 two-burner gas hob (£178)
  • Cut into worktop
  • Connects to bottle via regulator and hose
  • Needs high-level vent above it (installed roof vent)

Regulator:

  • 30mbar propane regulator (£18)
  • Connects bottle to hose

Professional certification: Cost me £180 for a Gas Safe engineer to check my installation, pressure test the system, and issue a certificate. Insurance requires this.

Heating — Diesel heater (what I use):

I tried gas heating (Propex HS2000). It was expensive (£680), used loads of gas, and dried out the air horribly.

Now I use a Chinese diesel heater (Vevor 5kW, £185). I know, I know. But it works brilliantly.

Installation:

  • Heater unit under the bed
  • Fuel line from heater to fuel tank (£45 kit)
  • Exhaust out through the floor (£28 exhaust kit)
  • Air intake also through floor
  • 12V power from fuse box (8A fuse)
  • Controller on wall by bed

Cost:

  • Heater unit: £185
  • Fuel tank and line: £45
  • Exhaust and intake: £28
  • Installation materials: £32
  • Professional check: £120 (not legal requirement but peace of mind)

Total: £410

Performance:

  • Heats the van from 2°C to 18°C in about 20 minutes
  • Fuel consumption: 0.1-0.3L per hour (incredibly cheap)
  • 12V power draw: 1-2A running, 8A on startup
  • Can run all night on less than a litre of diesel

I’ve used it for two winters. It’s been brilliant. Warm van in Scottish Highlands in January.

Alternative: 12V electric heater

Only works if you have massive battery and solar. I tried a 1kW diesel heater – it drew 83A from my battery. Killed it in an hour.

Step 7: Building the Furniture (5-10 days)

This is where your van becomes a home. I’m going to share my actual build process for my current setup.

Materials:

  • 12mm ply for structure: £32 per 2.4m x 1.2m sheet (I used 6 sheets = £192)
  • 6mm ply for panels: £22 per sheet (I used 4 sheets = £88)
  • 18mm ply for worktop base: £38 per sheet (I used 1 sheet)
  • Kitchen worktop offcut (beech, 28mm thick): £38 from B&Q
  • 2×2 timber for framing: £4.50 per 2.4m length (I used 12 lengths = £54)
  • Wood screws: £25 (various sizes)
  • Wood glue: £12
  • L-brackets and corner braces: £35
  • Hinges and catches: £28
  • Edge trim: £18

Total furniture materials: £528

My furniture build (step-by-step):

The bed frame (2 days):

Design:

  • 1.9m x 1.4m sleeping surface
  • 0.45m height (storage underneath)
  • 47mm x 75mm timber frame
  • 18mm ply base with slats on top
  • Removable in sections for access

Build process:

  1. Built frame from 2×2 timber (47mm x 75mm) — corners joined with corner braces
  2. Secured frame to floor and walls using L-brackets (8 total)
  3. Cut 18mm ply base to fit (1.9m x 1.4m)
  4. Cut slats from spare 2×2 timber (18 slats, 50mm spacing)
  5. Screwed slats to frame
  6. Made the front section removable (4 bolts) for access to storage

Storage under bed:

  • 3 plastic boxes (Really Useful Boxes 84L, £15 each)
  • Accessible from front when bed section is removed
  • Stores clothes, shoes, outdoor gear

The kitchen unit (3 days):

Design:

  • 0.9m long x 0.5m deep x 0.9m high
  • Worktop at 0.9m height (comfortable for cooking)
  • Storage cupboard underneath
  • Drawer for utensils
  • Gas hob cut into worktop
  • Sink next to hob

Build process:

Day 1:

  • Built frame from 2×2 timber
  • Attached to floor (L-brackets) and wall (screwed through ply lining)
  • Cut 12mm ply for sides, back, and internal dividers

Day 2:

  • Fitted cupboard door with piano hinge
  • Built drawer with simple runners (£12)
  • Added internal shelf in cupboard

Day 3:

  • Cut kitchen worktop to size (0.9m x 0.5m)
  • Cut hole for hob (template provided with hob)
  • Cut hole for sink
  • Fitted both with silicone sealant
  • Attached worktop to frame with screws from underneath

The seating (1 day):

Design:

  • L-shaped bench
  • 0.8m along one wall, 0.6m along back wall
  • 0.45m high (same as bed for visual consistency)
  • Storage underneath

Build:

  • 2×2 frame secured to floor and walls
  • 12mm ply top
  • 6mm ply sides and front
  • Hinged lid for access to storage
  • Cushions on top (bought separate, £65)

Overhead storage (2 days):

Design:

  • 1.8m long x 0.35m deep x 0.3m high
  • Above the bed
  • Two cupboards with doors

Build:

  • Frame from 2×2 timber
  • 6mm ply for top, bottom, sides, back
  • 6mm ply doors with simple hinges
  • Magnetic catches to keep doors closed
  • Secured to van ribs with heavy-duty L-brackets

Critical techniques I learned:

1. Everything must be secured Don’t just rest furniture on the floor. Screw it down. An unsecured unit becomes a projectile in a crash.

2. Account for the van’s curves Vans aren’t square. Walls curve. Floor isn’t flat. I measure each section individually and cut to fit.

3. Pre-drill everything Ply splits easily. Pre-drill all screw holes.

4. Round all edges I use a router with a roundover bit (£28). Every exposed edge gets rounded. My shins thank me.

5. Use wood glue AND screws Glue gives strength. Screws give clamping pressure while glue dries. Both together = strong joints.

6. Plan for expansion/contraction Wood moves with humidity. I leave 2-3mm gaps between panels. Fill with flexible sealant later if needed.

Step 8: Wall & Ceiling Lining (2-4 days)

You’re covering up the insulation and wiring with something that looks decent and protects everything.

My approach: 3mm ply throughout

Why 3mm ply:

  • Cheap (£17-£22 per 2.4m x 1.2m sheet)
  • Light (important for payload)
  • Easy to cut and fit around curves
  • Can be painted
  • Looks fine when painted

Alternative materials:

  • Tongue & groove cladding (£30-£45 per pack): Looks warmer, costs more, heavier
  • Vinyl panels (£25-£40 per pack): Quick install, wipe-clean, plasticky looking

Installation process:

Ceiling (Day 1-2):

  1. Cut 3mm ply to rough size (slightly oversize)
  2. Offer up to ceiling, mark where ribs are
  3. Remove, trim to exact size
  4. Pre-drill screw holes
  5. Apply construction adhesive to battens (I installed these over the insulation)
  6. Screw through ply into battens (25mm screws, every 200mm)
  7. Fill screw holes with wood filler
  8. Sand smooth (orbital sander, 120 grit)
  9. Paint (white ceiling paint, 2 coats)

I used 4 sheets for the ceiling. Cost: £80 for ply, £22 for paint.

Walls (Day 3-4):

Same process but more complex because of windows, doors, and curves.

Challenges:

  • Cutting around window apertures (cardboard templates first)
  • Fitting around door frames (measure three times, cut once)
  • Dealing with van curves (ply can flex slightly — use screws to pull it into shape)

I used 5 sheets for walls. Cost: £100 for ply, £28 for paint (light grey).

Finishing:

  • Filled all screw holes with decorator’s filler
  • Sanded everything smooth (took longer than the installation)
  • Painted ceiling white (makes it brighter)
  • Painted walls light grey (hides dirt better than white)
  • Added plastic edge trim where ply meets metal (£18)

Total cost: £248

What I learned:

  • Buy 20% more ply than you think you need (mistakes happen)
  • Paint BEFORE you install if possible (much easier)
  • Use a fine-tooth blade in your jigsaw for cleaner cuts
  • Accept that it won’t be perfect — character, not flaws

Step 9: Flooring (1 day)

Final major component. I’ve tried three different types across my conversions.

My journey:

Van 1: Carpet

  • Cost: £65
  • Pros: Warm, comfortable underfoot
  • Cons: Impossible to clean, holds moisture, smells after 6 months
  • Verdict: Never again

Van 2: Rubber gym flooring

  • Cost: £78
  • Pros: Durable, easy to clean, good grip
  • Cons: Looks industrial, smells rubbery for months, heavy
  • Verdict: Works but looks rubbish

Van 3 (current): Vinyl click-lock flooring

  • Cost: £118
  • Pros: Looks good, waterproof, easy to clean, easy to install
  • Cons: Can be cold underfoot (solved with rugs)
  • Verdict: Perfect

My installation process:

Prep:

  1. 12mm ply subfloor already installed over insulation (from Step 3)
  2. Swept and vacuumed thoroughly
  3. Checked floor is level (used shims under ply where needed)

Vinyl installation:

  1. Measured floor area (accounted for awkward shapes)
  2. Ordered vinyl (Wickes Warm Oak effect, £28 per pack, bought 5 packs = £140 including 20% spare)
  3. Started from front of van
  4. First row: Cut planks to width, clicked together
  5. Subsequent rows: Clicked into previous row, staggered joints
  6. Cut around wheel arches using cardboard template
  7. Left 5mm expansion gap around edges (covered with beading later)
  8. No adhesive needed (click-lock floats)

Time: 6 hours including all cuts and fitting

Finishing:

  • Fitted plastic edge beading around perimeter (£12)
  • Added a small rug in living area for warmth (£25)

Total flooring cost: £177 (vinyl + beading + rug)

Tips:

  • Use a jigsaw for cuts, not a Stanley knife (cleaner edges)
  • Click-lock needs a flat surface (ply subfloor essential)
  • Warm the vinyl in the sun before installing (makes it more flexible)

Step 10: Windows & Ventilation (Critical for condensation control)

I didn’t have proper ventilation in van #1. Had black mould on the ceiling within 3 months. Learned my lesson.

Why ventilation matters:

Two people sleeping generate about 1 litre of moisture overnight through breathing. Add cooking, wet clothes, dogs, etc. That moisture needs somewhere to go.

My ventilation setup:

Roof vent (essential):

  • Fiamma Turbo-Vent (£168)
  • Size: 400mm x 400mm
  • Two-way: Extracts stale air or brings fresh air in
  • 12V powered fan
  • Rain sensor (automatically closes when raining)

Installation (or pay someone £120-£180):

  1. Marked out position (centered, towards rear)
  2. Drilled pilot hole from inside
  3. Used jigsaw from outside to cut hole (terrifying — measure 10 times)
  4. Cleaned metal edges, applied rust treatment
  5. Applied Sikaflex 512 sealant around aperture
  6. Fitted vent from outside, screwed down (8 screws)
  7. Waited 24 hours for sealant to cure
  8. Connected 12V power inside
  9. Tested for leaks (hosepipe test)

Side windows:

My van came with one sliding window. I added a second fixed window on the other side.

Cost:

  • Window (second-hand from van breakers): £85
  • Fitting kit: £18
  • Sikaflex sealant: £12

Additional ventilation:

Door vents:

  • Fitted two air vents to the rear doors (low down)
  • Cost: £18 for pair
  • These allow air to enter while roof vent extracts

How it works: Fresh air enters through door vents → warms up → rises → exits through roof vent

This creates constant air circulation even when we’re asleep.

Condensation control:

Even with good ventilation, you’ll get some condensation. I manage it with:

  • Running the roof vent on low all night
  • Cracking a window slightly
  • Wiping windows in the morning (takes 30 seconds)
  • Not covering windows with poorly-designed covers (blocks airflow)

Total ventilation cost: £388 (roof vent + window + door vents + fitting)

Worth every penny. No mould. No major condensation issues.

Step 11: Final Touches (2-3 days)

The bits that make it liveable.

Window coverings:

I tried:

  • Stick-on insulation (£45): Looked rubbish, didn’t fit well
  • Curtains (£60): Awkward in a small space, always in the way
  • Magnetic insulation panels: This is what I use now

DIY magnetic covers:

  • Reflectix cut to window size
  • Covered in fabric (£22 for material)
  • Small magnets sewn into edges (£8 for pack of magnets)
  • Stick to metal window frame

Cost: £30 for all windows. Works brilliantly. Easy to remove during day.

Mattress (don’t cheap out):

I tried a £80 memory foam mattress from Amazon. My back hated me. Now I have a proper one.

Current mattress:

  • Duvalay 1.9m x 1.4m memory foam (£285)
  • 10cm thick
  • Comes with removable washable cover
  • Actually comfortable

Bedding:

  • Fitted sheet (£15)
  • Duvet suitable for the season (£45)
  • Pillows (£20)

Lighting:

Beyond my main LED strips, I added:

  • Two reading lights (Ikea USB rechargeable, £10 each)
  • One exterior light on rear door (£22)
  • One under-cupboard light in kitchen (£12)

Fire safety:

Essential:

  • Fire extinguisher (1kg ABC powder, £24)
  • Mounted near door where I can grab it easily
  • CO detector if you have gas (£18)
  • Smoke alarm (£15)

All three fitted. Non-negotiable.

Storage solutions:

What I added after living in it:

  • Magnetic knife strip (£8)
  • Hanging organizer for shoes (£12)
  • Collapsible washing up bowl (£8)
  • Folding crates for food storage (£15 for 3)
  • Head torch hooks by bed (£4)
  • Phone holder by bed (£6)

Total final touches: £496 (mattress being the big expense)

Realistic Cost Breakdown: Three Budget Levels

Let me give you three realistic scenarios based on builds I’ve done or helped with.

Budget Level 1: Basic Weekend Warrior (£4,500-£6,000 + van)

Base van: £8,000-£10,000 (older, higher mileage, but solid)

Conversion costs:

  • Insulation (basic): £250
  • Electrical (AGM battery, split charge, basic lights): £380
  • Plumbing (jerrycans, foot pump): £120
  • Furniture materials: £300
  • Flooring (basic vinyl): £80
  • Wall lining (painted ply): £180
  • Windows (none added): £0
  • Ventilation (roof vent): £180
  • Mattress (budget): £150
  • Final touches: £280
  • Tools (if needed): £450
  • Contingency/mistakes: £630

Total conversion: £5,000

Grand total: £13,000-£15,000

What you get:

  • Functional camper for weekend trips
  • Basic but comfortable
  • No frills
  • DIY everything

Budget Level 2: Comfortable Year-Round (£10,000-£13,000 + van)

Base van: £11,000-£14,000 (newer, better condition)

Conversion costs:

  • Insulation (Celotex throughout): £450
  • Electrical (lithium battery, DC-DC, solar, fridge): £1,200
  • Plumbing (pump system): £240
  • Gas system (hob + professional cert): £420
  • Heating (diesel heater): £380
  • Furniture materials (better quality): £550
  • Flooring (good vinyl): £180
  • Wall lining (painted ply + trim): £260
  • Windows (one added): £220
  • Ventilation (roof vent + extras): £380
  • Mattress (decent): £285
  • Final touches: £450
  • Tools: £350
  • Professional help (gas cert, window fitting): £280
  • Contingency/mistakes: £855

Total conversion: £12,500

Grand total: £23,500-£26,500

What you get:

  • Comfortable year-round living
  • All essentials covered
  • Can handle winter
  • Blend of DIY and professional work

This is roughly what I spent on my current van.

Budget Level 3: Premium Full-Timer (£18,000-£25,000 + van)

Base van: £15,000-£22,000 (low mileage, excellent condition, maybe LWB)

Conversion costs:

  • Insulation (spray foam professional): £1,800
  • Electrical (big lithium, inverter, 400W solar): £2,400
  • Plumbing (fixed tank, hot water): £650
  • Gas (hob + heater + professional): £1,200
  • Heating (Webasto diesel air heater): £1,400
  • Furniture (custom built, quality materials): £1,800
  • Flooring (premium LVT): £380
  • Wall lining (T&G cladding): £550
  • Windows (multiple added, skylights): £850
  • Ventilation (Maxxfan, multiple vents): £650
  • Wet room (if included): £1,200
  • Mattress (premium): £450
  • Final touches: £850
  • Professional carpentry: £2,400
  • Professional electrical: £1,200
  • Contingency: £2,220

Total conversion: £20,000

Grand total: £35,000-£42,000

What you get:

  • Full-time living comfort
  • Professional finish
  • All amenities
  • Shower, hot water, big battery
  • Trades doing specialist work

Most professional converters charge £25,000-£40,000 for this level.

Living With Your Conversion: The Reality

I’ve now lived with my conversion for 14 months. Used it for 120+ nights. Here’s what I’ve learned about actually living in it.

What works brilliantly:

The bed Best decision was making it comfortable. I sleep better in the van than in my house sometimes.

The kitchen Simple two-burner setup is perfect. I’ve cooked everything from full roast dinners to elaborate curries. You don’t need an oven.

The electrical system Lithium battery + solar = freedom. I’ve gone 3 weeks without hookup in summer.

The insulation Worth every penny. Stayed comfortable in -5°C Scottish winter and +28°C Cornwall summer.

What doesn’t work as well:

Storage No matter how much you have, it’s not enough. I’ve optimized three times and it’s still tight.

Working from the van Possible but not ideal. The table’s a bit small. Posture isn’t great. I usually find a cafe.

Cooking for more than 2 The kitchen’s great for two. Had friends over once. Chaos. Stick to simple meals for guests.

Showering I use campsites, wild swimming, or gym memberships. It’s fine but not convenient.

What I wish I’d added:

More USB charging points I have two twin USB sockets. I want four more. Phones, tablets, headphones, battery packs — everything needs charging.

A better table Mine’s a bit small and wobbly. Wish I’d built something more robust.

Exterior storage A roof box or rear storage box for bikes, outdoor gear, etc. would free up interior space.

What I’m glad I didn’t add:

A shower Would’ve taken up valuable space I use for storage. Campsite showers work fine.

An oven Adds weight, uses lots of gas, heats up the van. Don’t miss it.

Fixed furniture everywhere Modularity is gold. So glad I can remove the bed.

Common Problems & Solutions

Problem 1: Condensation

Despite good ventilation, you’ll get some condensation.

Solutions:

  • Run roof vent on low overnight
  • Wipe windows in morning (takes 30 seconds)
  • Don’t dry clothes inside (or expect condensation)
  • Small dehumidifier if full-time (£45, works on 12V or USB)

Problem 2: Things Breaking

Vans vibrate. Screws loosen. Things break.

Solutions:

  • Carry spare fuses, bulbs, screws
  • Use threadlock on screws that keep loosening
  • Check all connections monthly
  • Keep a toolkit in the van

Problem 3: Running Out of Power

Happens less with solar but still possible in winter.

Solutions:

  • Drive for 30-60 minutes to recharge
  • Use campsites with hookup
  • Reduce consumption (LED lights only, fridge on low)
  • Bigger battery (lithium upgrade worth it)

Problem 4: Running Out of Water

20L doesn’t last as long as you’d think.

Solutions:

  • Carry extra Jerry cans
  • Use public taps (parks, campsites, petrol stations)
  • Reduce waste (washing up bowl, not running tap)
  • Grey water can be used for flushing toilet

Problem 5: Finding Places to Stay

This is the real challenge in England and Wales.

Solutions:

  • Park4Night app (£10/year, best investment)
  • Britstops membership (£30/year, farm stays)
  • Arrive late, leave early
  • Have campsite backup options
  • Join vanlife groups for location sharing

Problem 6: Smells

Small space + cooking + bodies = smells.

Solutions:

  • Ventilation (obviously)
  • Take rubbish out daily
  • Baking soda in storage areas
  • Air freshener (I use lavender bags, £8)
  • Regular deep cleans

Problem 7: Broken Heater at Midnight in Scotland

Happened to me.

Solutions:

  • Always carry backup (warm sleeping bag)
  • Learn basic troubleshooting
  • Keep spares (glow plug for diesel heater, £12)
  • Don’t rely on one system

What I’d Do Differently Next Time

I’ve converted four vans. If I did number five (and I probably will), here’s what I’d change:

1. Buy a van with windows already fitted Cutting holes is nerve-wracking and expensive if you cock it up. Spend an extra £500 on a windowed van.

2. Spend more on the battery from day one I bought cheap AGM for £150. Lasted 18 months. Bought lithium for £450. Will last 10+ years. False economy.

3. Make even more furniture removable My bed comes out but it’s still a faff. I’d design everything to be modular from the start.

4. Better soundproofing I did 70% coverage. Should’ve done 90%. Every stone hitting the underside is loud.

5. Professional gas certification from the start I avoided gas initially, then wanted it later and had to retrofit. Cost more in the end.

6. Better cable management My wiring works but it’s messy behind the panels. Would install proper cable trays from the start.

7. More overhead storage I have one overhead cupboard. Wish I’d built three.

8. Bigger worktop 90cm is okay. 120cm would’ve been better. More prep space for cooking.

9. Exterior shower Not for me, but a simple shower point on the outside (£35 worth of parts) would be handy for rinsing sandy feet.

10. Documentation as I built I wish I’d photographed more during the build. Helps when troubleshooting later.

Final Thoughts: Is It Worth It?

Converting a campervan is expensive, time-consuming, occasionally frustrating, and you’ll absolutely make mistakes.

It’s also one of the most rewarding things I’ve ever done.

When you’re parked up somewhere stunning, cooking breakfast while looking at a view that cost nothing, sitting in a space you built with your own hands, knowing you can bugger off to Scotland or Wales or Cornwall whenever you fancy — that’s worth all the hassle.

But be realistic. This isn’t Instagram. It’s:

  • Cold mornings wiping condensation
  • Cooking in the rain with a door open
  • Finding parking at 10pm
  • Dealing with broken heaters and flat batteries
  • Explaining to yet another person that no, you don’t have a shower

If you’re okay with that reality, build the van.

Start small. Don’t aim for perfection. Build what you need, not what looks good on social media.

And for the love of everything, don’t skip the insulation.

Now stop reading and start building. And when you cock something up (you will), at least you’ll have learned something.

Essential Resources:

  • Forums: Wildcamping.co.uk, T4/T5/T6 Forum, UKCampsite
  • Apps: Park4Night (£10/year), iOverlander (free)
  • YouTube: Nate Murphy (for electrical), FortyNotOut Campers (UK specific)
  • Suppliers: 12V Planet (electrical), CampervanHQ (gas), Screwfix/Toolstation (everything else)
  • Groups: UK Vanlife Facebook groups (search by your van model)

Continue Reading
By
Electrical & Off-Grid Power

Installing a 12v And 240v Campervan System

No Comments

I’ve installed complete electrical systems in four vans now. The first installation took me four weekends, involved two rewiring sessions when I realized I’d cocked up the layout, and resulted in a blown fuse.

The most recent installation took me three days start to finish with zero mistakes and perfect cable management. The difference? Understanding the installation sequence, having every component and tool ready before starting, and actually drawing a proper wiring diagram instead of “figuring it out as I go.”

Here’s what nobody tells you: electrical installation isn’t difficult—it’s unforgiving. Make a mistake in planning and you can fix it. Make a mistake in wiring and you might not discover it until something fails, catches fire, or leaves you stranded with no power. The key is methodical planning, proper testing at every stage, and never assuming a connection is good until you’ve verified it.

I’ve made every installation mistake: wrong cable sizes, forgotten fuses, reversed polarity, poor crimping, inadequate testing, crossed circuits. This guide contains everything I wish someone had told me before my first installation.

This is a complete, step-by-step guide to installing both 12V and 240V electrical systems in campervans: the planning phase everyone skips, the installation sequence that prevents rework, the testing procedures that catch problems early, and the mistakes that cost me days of work so they don’t cost you anything.

Table of Contents

  1. Pre-Installation Planning
  2. Tools and Materials
  3. Battery Installation
  4. Main Distribution System
  5. 12V Circuit Installation
  6. DC-DC Charger Installation
  7. Inverter Installation
  8. 240V System Installation
  9. System Integration
  10. Testing and Commissioning
  11. Cable Management
  12. Troubleshooting

Pre-Installation Planning

Don’t touch a wire until you’ve completed this phase. I’m serious.

Step 1: Create a Wiring Diagram

Don’t skip this. Every time I’ve skipped diagrams, I’ve regretted it.

What to draw:

  1. Power source (battery)
  2. Protection (main fuse)
  3. Distribution (bus bar)
  4. Every circuit:
    • Lights (with switch)
    • Fridge (with fuse)
    • Water pump (with switch and fuse)
    • USB outlets (with fuse)
    • Heater (with switch and fuse)
    • Inverter (with switch and fuse)
  5. Charging sources:
    • Solar controller
    • DC-DC charger
    • Mains charger (if hookup)
  6. Monitoring (battery shunt)

Tools for diagrams:

  • Paper and pencil (simple, effective)
  • draw.io (free online)
  • Circuit design software (overkill but pretty)

My method: Paper diagram with colored pencils

  • Red = positive 12V
  • Black = negative/ground
  • Blue = 230V live
  • Green/yellow = earth
  • Different line thickness for different cable sizes

Step 2: Physical Component Layout

Mark on van floor plan:

  1. Battery location (under seat, under bed, etc.)
  2. Distribution point (bus bar location)
  3. Each device location:
    • Lights (ceiling, reading lights)
    • Fridge (kitchen area)
    • Water pump (near tank)
    • USB outlets (bedside, kitchen)
    • Switches (control panel)
  4. Charging equipment:
    • Solar controller (near battery)
    • DC-DC charger (near battery)
    • Inverter (near battery)
  5. 240V components (if installing):
    • Hookup inlet (exterior wall)
    • RCD/consumer unit (accessible location)
    • 230V sockets (kitchen, maybe bedside)

Measure distances for cable routing:

  • Battery to bus bar
  • Bus bar to each device
  • Add 20% for routing (cables don’t run straight)

Step 3: Calculate Cable Sizes

For each circuit, calculate:

  1. Maximum current
  2. Cable length (actual route, not straight line)
  3. Acceptable voltage drop (3% maximum)
  4. Required cable size (from voltage drop calculation)

Example: LED lighting circuit

  • Current: 5A maximum
  • Length: 4m from bus bar to lights
  • Voltage drop formula: (5A × 4m × 2 × 8.0mΩ/m) ÷ 1000 = 0.32V
  • Percentage: 0.32V ÷ 12V = 2.7%
  • Cable: 2.5mm² is adequate

Do this for every circuit before buying cable.

Step 4: Create Shopping List

From your diagram and calculations:

Cables (buy 10% extra):

  • 2.5mm²: ___m
  • 4mm²: ___m
  • 6mm²: ___m
  • 16mm²: ___m (battery connections)
  • 25mm²: ___m (inverter, if needed)

Terminals and connectors:

  • Ring terminals (various sizes for cable gauges)
  • Blade terminals
  • Butt connectors
  • Heat shrink tubing (various diameters)

Fusing:

  • ANL fuse + holder (main battery)
  • Blade fuses + holders (each circuit)
  • Spare fuses (always have spares)

Distribution:

  • Bus bars (positive and negative)
  • Mounting hardware
  • Cable ties

Switches:

  • Rocker switches (for each switched circuit)
  • Mounting panel or enclosure

Protection:

  • RCD (if 240V system)
  • Circuit breakers or fuse holders

Connectors:

  • Anderson connectors (optional, for removable devices)
  • MC4 connectors (solar)
  • Appropriate 230V connectors

Step 5: Plan Installation Sequence

Correct order prevents rework:

  1. Install battery (secure, fused)
  2. Install bus bar system (distribution point)
  3. Run main power cables (battery to bus bar)
  4. Install DC-DC charger (connects to battery)
  5. Install solar controller (connects to battery)
  6. Run 12V circuit cables (bus bar to devices)
  7. Install inverter (connects to battery)
  8. Install 240V system (if needed)
  9. Connect all devices
  10. Test each circuit individually
  11. Test complete system
  12. Cable management (final tidy)

Why this order?

  • Battery first (power source for testing)
  • Distribution second (connection point for everything)
  • Charging before loads (can test as you go)
  • Devices last (easier to test circuits before connecting loads)
  • Cable management last (don’t tidy until everything works)

Tools and Materials

Here’s what you actually need. Having everything ready saves hours.

Essential Tools

Hand tools:

  • Wire strippers (good quality, £15-30)
  • Crimping tool (hydraulic is best, £30-80)
  • Screwdrivers (Phillips and flat, various sizes)
  • Spanners (8mm-13mm typical)
  • Socket set (10mm-13mm)
  • Cable cutters (for thick cables)
  • Knife or cable stripper

Power tools:

  • Cordless drill (12V minimum, 18V better)
  • Drill bits (2mm, 3mm, 4mm, 6mm, 8mm)
  • Hole saw set (for cable entry, switch mounting)
  • Step drill bit (optional but excellent for clean holes)

Testing equipment:

  • Multimeter (essential, £20-100)
  • DC clamp meter (very useful, £40-80)
  • Test light (quick continuity checks)
  • Cable tracer (optional, useful for finding cables)

Safety:

  • Safety glasses
  • Work gloves
  • Fire extinguisher (nearby)
  • First aid kit

My toolkit (what I actually use):

  • Engineer PA-09 crimping tool (£35)
  • Klein wire strippers (£20)
  • DeWalt drill (already owned)
  • Fluke 117 multimeter (£150, cheaper ones work fine)
  • Standard socket set
  • Step drill bit (£18)

Materials Checklist

Cables (automotive grade, stranded):

  • Red cable (positive): 2.5mm², 4mm², 6mm², 16mm²
  • Black cable (negative): matching sizes
  • Yellow/green (earth, for 230V): 2.5mm²

Terminals:

  • Ring terminals: M6, M8, M10 (various cable sizes)
  • Blade terminals: male and female
  • Butt connectors (various sizes)
  • Heat shrink: 3mm, 5mm, 8mm, 12mm, 20mm

Fusing:

  • ANL fuse holder + 80-125A fuse (main battery)
  • Blade fuse holders (one per circuit)
  • Assorted blade fuses: 5A, 10A, 15A, 20A, 30A
  • MIDI fuse holder + fuse (inverter, if needed)

Distribution:

  • 12-way positive bus bar with fuse holders
  • Negative bus bar (6-12 way)
  • Earth bus bar (if 230V system)
  • Mounting screws and standoffs

Switches and controls:

  • Rocker switches: 10A or 20A rated
  • Switch panel or enclosure
  • LED indicators (optional)

Cable management:

  • Cable ties (UV resistant, various sizes)
  • Split loom conduit (10mm, 15mm, 20mm)
  • Cable clips and saddles
  • Grommets (for panel pass-throughs)
  • Adhesive cable tie mounts

Protection:

  • RCD (30mA, if 240V)
  • Consumer unit (2-4 way, if 230V)
  • Rubber grommets (various sizes)
  • Conduit (for 230V cables)

Sealant and adhesives:

  • Sikaflex or similar (cable entries through walls)
  • Double-sided tape (temporary holding)
  • Cable clamp adhesive mounts

Labels:

  • Cable labels or label maker
  • Permanent marker
  • Coloured tape (circuit identification)

Estimated Costs

Basic 12V system (no 230V):

  • Cables and terminals: £80-120
  • Fusing and distribution: £60-90
  • Switches and panel: £40-60
  • Cable management: £30-50
  • Tools (if buying): £100-200
  • Total materials: £210-320
  • Total with tools: £310-520

Complete 12V + 240V system:

  • Above plus:
  • 240V cables and components: £60-90
  • RCD and consumer unit: £50-80
  • 230V sockets and switches: £30-50
  • Additional protection: £40-60
  • Total materials: £390-600
  • Total with tools: £490-800

My actual spend (medium system, had some tools):

  • Materials: £380
  • New tools: £55 (crimping tool, step bit)
  • Total: £435

Battery Installation

First component in. Get this right—everything else depends on it.

Step 1: Choose Location

Requirements:

  • Low in van (center of gravity)
  • Accessible (for connections and maintenance)
  • Secure (won’t move in accident)
  • Ventilated (lead-acid) or enclosed (lithium okay)
  • Protected from damage

Common locations:

  • Under seating (my choice)
  • Under bed platform
  • In front passenger footwell (single-seat vans)
  • Dedicated battery box in storage area

My location: Under passenger seat, secured to floor with L-brackets.

Step 2: Build Battery Box (If Needed)

For lead-acid batteries (hydrogen gas):

  • Sealed box with vent to outside
  • Sturdy construction (battery is heavy)
  • Acid-resistant material (plastic, coated wood)
  • Secure lid with access for connections

For lithium batteries:

  • Protection from physical damage
  • Doesn’t need venting
  • Can be more compact
  • Still needs secure mounting

My setup (lithium):

  • No box (under seat is protected)
  • Secured with L-brackets bolted to floor
  • Strap over top (additional security)
  • Easy access to terminals

Step 3: Secure Battery

Critical: Battery must not move in accident. A 25kg battery becoming a projectile in a crash is lethal.

Methods:

L-bracket mount:

  1. Drill floor (through to chassis if possible)
  2. Bolt L-brackets to floor
  3. Battery sits between brackets
  4. Strap over top

Ratchet strap:

  1. Anchor points on either side
  2. Ratchet strap over battery
  3. Tighten securely
  4. Check regularly (can loosen over time)

Battery box:

  1. Box bolted to floor
  2. Battery inside box
  3. Lid secured
  4. Additional strap recommended

My installation:

  • Two L-brackets, one each side of battery
  • Bolted through floor to chassis members
  • Ratchet strap over top (belt and braces)
  • Checked tightness every 3 months

Step 4: Install Main Fuse

Critical safety: Fuse on positive terminal, within 300mm of battery.

Process:

  1. Select fuse rating:
    • Calculate maximum current (all loads + charging)
    • My system: Max 80A from all sources
    • Fuse rating: 100A ANL (125% of maximum)
  2. Connect fuse holder to battery:
    • ANL fuse holder with ring terminals
    • Red cable: 16-25mm² (short run, high current)
    • Ring terminal sized for battery post (M8 or M10 typical)
    • Crimp terminal onto cable
    • Connect to battery positive
  3. Verify polarity (before going further):
    • Battery positive = red cable
    • Battery negative = black cable
    • Double-check with multimeter
  4. Insert fuse (do this last, after everything else is wired):
    • Keeps system dead during installation
    • Insert fuse when ready to power up

Step 5: Main Negative Connection

Process:

  1. Cable from battery negative to negative bus bar
    • Same size as positive (16-25mm²)
    • Black cable
    • Ring terminal at battery end
    • Ring or cable lug at bus bar end
  2. No fuse on negative (common mistake):
    • Negative is ground/return path
    • Fusing negative would prevent fuses from working correctly
    • Only positive gets fused
  3. Short as practical:
    • Minimize cable length
    • Reduce voltage drop
    • My run: 0.8m from battery to bus bar

Step 6: Battery Shunt Installation (If Monitoring)

For battery monitors (Victron SmartShunt, Renogy monitor):

Critical rule: ALL negative current must flow through shunt

Installation:

  1. Disconnect battery negative from bus bar (if already connected)
  2. Install shunt on battery negative terminal:
    • Shunt battery side to battery negative post
    • Shunt load side to negative bus bar
  3. Connect shunt signal cable:
    • Small wire from shunt to monitor/controller
    • Route carefully (don’t damage)
  4. Power wire for monitor:
    • Thin positive wire from battery to shunt/monitor
    • Through small fuse (1-2A)

Result: All negative current flows Battery → Shunt → Bus Bar → Devices → Back to Bus Bar → Shunt → Battery

The shunt measures everything.

My installation: Victron SmartShunt

  • Mounted directly on battery negative post
  • All negatives route through it
  • Signal cable to Bluetooth module
  • Power from battery positive (1A fuse)

Main Distribution System

The central hub where everything connects.

Step 1: Choose Bus Bar Location

Considerations:

  • Near battery (short main cable runs)
  • Accessible (for adding circuits)
  • Protected (behind panel or in cabinet)
  • Space for future expansion

My location: Electrical cabinet on rear wall, 1m from battery.

Step 2: Mount Bus Bars

You need two:

  1. Positive bus bar (fused)
  2. Negative bus bar (unfused)
  3. Earth bus bar (if 240V system)

Mounting:

  1. Cut backing board (plywood or similar):
    • Size to fit bus bars with space around
    • My board: 400mm × 300mm
  2. Mount bus bars to board:
    • Positive bar: Blade fuse holders (6-12 positions)
    • Negative bar: Screw terminals (6-12 positions)
    • Use standoffs (prevent shorts to board)
  3. Mount board to van:
    • Screw to wall or floor
    • Ensure secure (will have cable tension)

My setup:

  • 12-position positive bus with blade fuse holders
  • 10-position negative bus
  • 6-position earth bus (for 230V)
  • All mounted on plywood board
  • Board screwed to rear wall cabinet

Step 3: Main Power Cables

From battery to bus bar:

Positive cable:

  1. From battery main fuse to positive bus bar:
    • Cable size: 16-25mm² (depends on max current)
    • My system: 16mm² (adequate for 100A)
    • Length: 1m in my van
  2. Crimp ring terminal at bus bar end:
    • Large terminal (M8 or M10)
    • Proper crimping
    • Heat shrink over connection
  3. Connect to bus bar input:
    • Usually a large bolt/stud
    • Tighten securely
    • Verify connection

Negative cable:

  1. From battery (through shunt if monitoring) to negative bus bar:
    • Same size as positive (16mm² in my case)
    • Black cable
    • Ring terminals both ends
  2. Connect to bus bar:
    • Main input terminal
    • Tighten securely

Testing before proceeding:

  1. DON’T insert main fuse yet
  2. Check for shorts:
    • Multimeter in continuity mode
    • Test positive bus to negative bus
    • Should NOT have continuity (open circuit)
    • If continuity exists, find and fix short
  3. Only when verified no short:
    • Insert main fuse
    • System is now live
    • Verify voltage at bus bars (12.4-13.2V typical)

12V Circuit Installation

Now we wire each circuit from bus bar to device.

Step 1: Plan Circuit Routing

For each circuit, plan:

  1. Cable route from bus bar to device
  2. Switch location (if switched circuit)
  3. Cable size (from earlier calculations)
  4. Fuse rating (load current × 1.25)

Example: LED lighting circuit

  • Route: Bus bar → control panel (switch) → ceiling → lights
  • Switch: Panel-mounted rocker switch
  • Cable: 2.5mm² (5A load)
  • Fuse: 10A (5A × 1.25 = 6.25A, round to 10A)

Step 2: Run Cables

General process for each circuit:

  1. Measure cable length:
    • Actual route (not straight line)
    • Add 10% for connections and mistakes
  2. Cut positive and negative cables:
    • Same length
    • Same size
    • Mark each (label which circuit)
  3. Route cables together:
    • Keep positive and negative together
    • Use cable loom or ties
    • Secure every 30-50cm
    • Protect through metal panels (grommets)
  4. Leave slack:
    • 10-15cm extra at each end
    • Allows for connection and future service
    • Don’t pull guitar-string tight

Step 3: Install Switches (Switched Circuits)

For circuits with switches:

Switch wiring:

  • Positive from bus bar → switch → device
  • Negative from bus bar → device (direct)
  • Switch only breaks positive (standard practice)

Installation:

  1. Mount switch panel:
    • Accessible location
    • Secure mounting
    • Appropriate size holes
  2. Wire switch:
    • Positive IN from bus bar
    • Positive OUT to device
    • Use blade terminals on switch tabs
    • Or solder and heat shrink (more reliable)
  3. Test switch:
    • Continuity test
    • Should conduct when ON
    • Open circuit when OFF

My control panel:

  • 8 rocker switches (lights, pump, heater, etc.)
  • Panel-mounted in overhead cabinet
  • All switches break positive
  • Each labeled clearly

Step 4: Connect Circuits to Bus Bar

Positive connections:

  1. Strip cable (10-12mm)
  2. Crimp ring terminal:
    • Size appropriate for cable
    • Proper crimping (critical)
    • Heat shrink over connection
  3. Insert fuse in bus bar position:
    • Correct rating for circuit
    • Blade fuse in fuse holder
  4. Connect terminal under fuse holder screw:
    • Tighten securely
    • Verify terminal seated properly

Negative connections:

  1. Strip cable (10-12mm)
  2. Crimp ring terminal or use bare wire:
    • Ring terminal more reliable
    • Bare wire acceptable for screw terminals
  3. Connect to negative bus bar:
    • Under screw terminal
    • Tighten securely

Testing each circuit:

Before connecting device:

  1. Check fuse continuity:
    • Should have continuity through fuse
    • Voltage at circuit cable should match bus bar
  2. Check for shorts:
    • Measure resistance positive to negative
    • Should be high (infinite on most meters)
    • Low resistance = short (find and fix)
  3. Switch test (if switched):
    • Voltage should appear/disappear with switch

Step 5: Connect Devices

Only after circuit testing:

Lights:

  1. Identify polarity:
    • LED strips: Usually marked positive/negative
    • Individual LEDs: Red = positive, black = negative
  2. Connect wires:
    • Solder preferred (most reliable)
    • Or use connector blocks
    • Heat shrink over connections
  3. Test:
    • Switch on
    • Light should illuminate
    • Check brightness (dim = voltage drop or wrong voltage)

Water pump:

  1. Connect positive to switch output
  2. Connect negative to negative bus
  3. Test:
    • Press switch
    • Pump should run
    • Check current draw (should match rating)

USB outlets:

  1. Connect positive to fused circuit
  2. Connect negative
  3. Test with phone:
    • Should charge normally
    • Check voltage at outlet (should be 5V ±0.25V)

Fridge:

  1. Usually direct connection (not switched):
    • Positive to fused bus bar position
    • Negative to bus bar
    • Fridge often has internal switch
  2. Large fuse (fridge draws significant current):
    • 10-15A typical for compressor fridge
  3. Thick cable (4-6mm²):
    • Fridges draw 5-8A when running
    • Prevent voltage drop

My fridge installation:

  • Direct to bus bar (20A fused circuit)
  • 4mm² cable, 3m run
  • Voltage drop: 0.36V (acceptable)
  • Fridge has internal thermostat (controls on/off)

Diesel heater:

  1. Check manufacturer specs:
    • Most draw 10-25W (1-2A)
    • Some draw more on startup
  2. Fused circuit (10A typical)
  3. Switched or direct:
    • Mine is switched (heater also has controller)
  4. Earth/ground (some heaters require):
    • Connect to van chassis
    • Manufacturer instructions

Step 6: Label Everything

Don’t skip this:

At bus bar:

  • Label each circuit position
  • “Lights Main”, “Fridge”, “Water Pump”, etc.

At devices:

  • Label cable at device end
  • Future troubleshooting

At switches:

  • Label what each switch controls

My method: Label maker plus colored heat shrink

  • Red = lights
  • Blue = pumps/water
  • Green = heating
  • Yellow = USB/charging
  • White = misc

DC-DC Charger Installation

Connects starter battery to leisure battery for charging while driving.

Step 1: Location

Requirements:

  • Near leisure battery (short cable runs)
  • Accessible (for monitoring LED indicators)
  • Ventilated (generates heat)
  • Protected from moisture

My location: Mounted on wall next to leisure battery, 0.5m away.

Step 2: Cable Sizing

From starter battery to DC-DC input:

  • Long run (5-8m typical)
  • High current (30-60A)
  • Thick cable needed (16-35mm²)

Example: 30A DC-DC, 6m run from starter battery

  • Voltage drop target: <3%
  • Required: 25mm² cable minimum
  • I used: 25mm² (just adequate)

From DC-DC output to leisure battery:

  • Short run (0.5-1m)
  • Same current as input
  • Same cable size (16-25mm²)

Step 3: Starter Battery Connection

Safety first: Disconnect starter battery negative before working.

Process:

  1. Identify starter battery positive:
    • Under bonnet
    • Usually near engine
  2. Install fuse holder:
    • Within 300mm of starter battery positive
    • Fuse rating: DC-DC current × 1.25
    • Example: 30A charger = 40A fuse
  3. Connect cable:
    • Ring terminal to battery post
    • Through fuse holder
    • Route carefully (avoid heat, moving parts)
  4. Route through bulkhead:
    • Find existing grommet/hole
    • Or drill new hole (seal with grommet and sealant)
    • Protect cable with additional sleeve
  5. Run to DC-DC charger location:
    • Secure every 30-50cm
    • Avoid heat sources
    • Protect from chafing

Negative from starter battery:

  • Connect to chassis/earth point near starter battery
  • Or run separate negative (better but more cable)
  • I used chassis ground (adequate)

Step 4: Leisure Battery Connection

DC-DC output to leisure battery:

  1. Positive output from DC-DC:
    • To leisure battery positive
    • Through fuse (30-60A depending on charger)
    • Short cable run (0.5-1m)
  2. Negative output from DC-DC:
    • To leisure battery negative
    • Through shunt (if battery monitoring)
    • Or direct to battery
  3. Proper crimping:
    • Thick cable needs good crimps
    • Use hydraulic crimping tool if possible
    • Heat shrink over connections

Step 5: DC-DC Configuration

Check manufacturer instructions:

Some DC-DC chargers require:

  • Configuration switches (battery type)
  • DIP switches (voltage settings)
  • Programming (via app or buttons)

My Renogy 30A DC-DC:

  • DIP switches for battery type (set to lithium)
  • No programming needed
  • Automatic operation when engine running

Step 6: Testing

Before first start:

  1. Check all connections tight
  2. Verify polarity:
    • Input positive to starter positive
    • Output positive to leisure positive
    • Negatives to negatives/ground
  3. Start engine:
    • DC-DC should activate (LED indicator)
    • Multimeter on leisure battery should show rising voltage
    • Should see 14.2-14.6V (charging voltage)
  4. Check current flow:
    • Clamp meter on output cable
    • Should see charging current (20-40A typical)
    • Reduces as battery charges

My testing results:

  • Engine start: DC-DC activated (green LED)
  • Leisure battery: 12.8V → 14.4V (charging)
  • Current: Started at 28A, reduced to 15A after 30 mins
  • Success

Inverter Installation

Converts 12V DC to 230V AC for household devices.

Step 1: Location Selection

Requirements:

  • Very close to battery (massive current draw)
  • Ventilated (generates heat)
  • Accessible (for on/off switch)
  • Space for cable routing

My location: Under passenger seat next to battery, 0.5m away.

Step 2: Cable Sizing (Critical)

Inverter draws huge current:

Example: 1000W inverter

  • Power: 1000W
  • Voltage: 12V
  • Efficiency: 90%
  • Current: 1000W ÷ 12V ÷ 0.9 = 93A

That’s massive current.

Cable sizing:

  • 1000W inverter, 0.5m cable run
  • 93A current
  • Need: 25mm² minimum (I used 35mm² for safety)

If cable is too thin:

  • Overheats (fire risk)
  • Voltage drop (inverter shuts down)
  • Efficiency loss

Step 3: Fusing

Fuse rating: Inverter max current × 1.25

Example: 1000W inverter (93A typical, 120A peak)

  • Fuse: 125-150A
  • I used: 125A MIDI fuse

Fuse location: Within 300mm of battery positive

Step 4: Physical Installation

Mounting inverter:

  1. Secure mounting:
    • Bolted to floor or wall
    • Won’t vibrate loose
    • Adequate ventilation (100mm clear space around)
  2. Cable connections:
    • Positive: Battery positive → fuse → inverter
    • Negative: Battery negative → inverter
    • Use large ring terminals (M8 or M10)
    • Hydraulic crimping essential (thick cables)
  3. Switch (recommended):
    • High-current switch on positive
    • Or remote on/off (many inverters have this)
    • Prevents parasitic drain when not in use

My installation:

  • Inverter bolted to floor under seat
  • 35mm² cables (positive and negative)
  • 125A fuse, 200mm from battery
  • Remote on/off switch on control panel

Step 5: 230V Output

From inverter 230V output:

If simple setup (one or two devices):

  • UK socket connected directly to inverter output
  • Simple but limited

If multiple devices:

  • Install small consumer unit
  • Distribute to multiple sockets
  • More complex but flexible

My setup: Direct connection

  • Single 230V socket near battery
  • Extension lead when needed
  • Simple, adequate for my usage

Step 6: Testing

Safety first: 230V can kill.

Testing procedure:

  1. Inverter OFF, check wiring:
    • Polarity correct (positive to positive)
    • All connections tight
    • No bare wire exposed
  2. Turn inverter ON:
    • Should power up (LED or display)
    • May beep or make noise (normal)
  3. Check output voltage:
    • Multimeter on AC setting
    • Should read 230V ±10V
    • My inverter: 232V (perfect)
  4. Test with load:
    • Plug in laptop charger or similar
    • Should work normally
    • Check inverter isn’t overheating
  5. Check current draw from battery:
    • Clamp meter on 12V input cable
    • 100W load should draw ~10A from battery
    • Matches expected current

Warning signs:

  • Voltage way off (210V or 250V = problem)
  • Excessive heat (inverter too small or poor ventilation)
  • Strange noises (could indicate fault)
  • Shutdowns (voltage drop or overload)

240V System Installation

For hookup and inverter-powered 230V circuits. This is dangerous voltage.

Safety Warning

230V can kill you. If you’re not confident, hire a qualified electrician.

Safety rules:

  • Never work on live 230V
  • Always disconnect before working
  • Use RCD protection (essential)
  • Test cables are dead before touching
  • Follow regulations (BS 7671 in UK)

Step 1: Hookup Inlet Installation

If adding campsite hookup capability:

Location:

  • Exterior wall (access from outside)
  • Low on vehicle (near ground)
  • Protected from road spray
  • Accessible when parked

Installation:

  1. Cut hole in exterior wall:
    • Size for inlet (usually 60-80mm)
    • Use hole saw
    • Deburr edges
  2. Mount hookup inlet:
    • Gasket between inlet and wall
    • Secure with screws
    • Weatherproof
  3. Wire connections (inside van):
    • Live (brown) to RCD live
    • Neutral (blue) to RCD neutral
    • Earth (green/yellow) to earth bus bar

My installation:

  • Inlet on rear corner (low)
  • 3-pin 16A inlet (standard campsite)
  • Gasket sealed, no leaks in 2 years

Step 2: RCD Installation

RCD (Residual Current Device) = lifesaver.

What it does: Trips in milliseconds if current leakage detected (e.g., you touch live wire).

Specification:

  • 30mA trip current (for human protection)
  • Rated for system current (16A typical for vans)

Installation:

  1. Mount RCD:
    • Accessible location
    • Din rail or panel mount
    • First component after hookup inlet
  2. Wire hookup inlet to RCD input:
    • Live to RCD live in
    • Neutral to RCD neutral in
    • Earth to earth bus (not through RCD)
  3. Test RCD:
    • Test button should trip RCD
    • Should reset after testing
    • If doesn’t trip, RCD is faulty (replace)

Step 3: Consumer Unit Installation

Distributes 230V to multiple circuits:

Components:

  • MCBs (Miniature Circuit Breakers) for each circuit
  • Or fuse holders
  • Bus bars for distribution

Wiring:

  1. RCD output to consumer unit input
  2. Each circuit:
    • Live through MCB (6A or 10A typical)
    • Neutral to neutral bus bar
    • Earth to earth bus bar
  3. Circuits:
    • Kitchen socket: 10A MCB
    • Bedside socket: 6A MCB
    • Inverter feed: 10A MCB
    • Mains battery charger: 6A MCB

My system:

  • 4-way consumer unit
  • Each socket on separate MCB
  • Allows isolation of individual circuits

Step 4: 230V Socket Installation

Standard UK 3-pin sockets:

Location planning:

  • Kitchen (for blender, kettle, etc.)
  • Bedside (for phone charging, laptop)
  • Workstation (if remote work setup)

Installation:

  1. Mount socket back box:
    • Secure to wall
    • Flush mount or surface mount
  2. Run cable from consumer unit:
    • 2.5mm² three-core cable (live, neutral, earth)
    • Protect in conduit
    • Secure every 30cm
  3. Wire socket:
    • Live (brown) to L terminal
    • Neutral (blue) to N terminal
    • Earth (green/yellow) to E terminal
    • Double-check colors
  4. Test before closing up:
    • Voltage test (230V between L and N)
    • Earth continuity test
    • RCD trip test

My sockets:

  • Two sockets (kitchen and bedside)
  • Surface-mounted (easier in van)
  • Separate MCB protection
  • Both work from hookup or inverter (switchable)

Step 5: Mains Battery Charger

Charges leisure battery from hookup:

Installation:

  1. Mount charger:
    • Near battery
    • Ventilated
    • Protected from moisture
  2. 230V input:
    • From consumer unit (6A MCB)
    • Three-core cable
    • Proper strain relief
  3. 12V output to battery:
    • Positive to battery positive (fused)
    • Negative to battery negative
    • Same as other charging sources
  4. Configure charger:
    • Battery type (lithium/AGM/etc.)
    • Charging voltage
    • Current limit

My charger (Victron Blue Smart 20A):

  • Connected to consumer unit
  • Auto-detects hookup connection
  • Charges battery automatically
  • Bluetooth monitoring (see status on phone)

Step 6: Switchover System

Choose power source (hookup vs inverter):

Option 1: Manual changeover

  • Switch between hookup and inverter
  • Simple, cheap
  • Must remember to switch

Option 2: Automatic transfer switch

  • Detects hookup presence
  • Switches automatically
  • More expensive (£80-150)
  • Better user experience

Option 3: Separate circuits

  • Hookup powers some sockets
  • Inverter powers others
  • No switching needed
  • Simple but less flexible

My setup: Manual switch

  • Three-position switch: OFF / Hookup / Inverter
  • Feeds 230V socket circuits
  • Must manually select (acceptable for my usage)

Step 7: Earthing

Critical for safety:

All 230V equipment must be earthed.

Earth system:

  1. Earth bus bar:
    • All earth wires connect here
    • Including: sockets, appliances, metal parts
  2. Van chassis:
    • Connect earth bus to chassis
    • Large cable (6-10mm²)
    • Ensures fault current has path to ground
  3. Hookup earth:
    • When on hookup, earth from campsite
    • Provides earth reference
    • Essential for RCD operation

My earthing:

  • Earth bus bar in consumer unit
  • Connected to chassis (10mm² cable)
  • All sockets earthed
  • All metal components bonded to earth

System Integration

Bringing everything together into one coherent system.

Step 1: Final Connections

Verify before powering up:

  1. Every circuit has fuse
  2. All connections tight
  3. No bare wires exposed
  4. Polarity correct everywhere
  5. Cable strain relief adequate

Create final checklist:

  • [ ] Battery secured
  • [ ] Main fuse installed (last step)
  • [ ] Bus bars mounted
  • [ ] All 12V circuits connected and fused
  • [ ] DC-DC charger wired and tested
  • [ ] Solar controller wired (if installed)
  • [ ] Inverter wired and fused
  • [ ] 240V RCD installed and tested
  • [ ] All 230V circuits protected
  • [ ] Earth bonding complete
  • [ ] No shorts detected (multimeter test)

Step 2: Power-Up Sequence

Don’t just flip everything on at once.

Sequence:

  1. Insert main fuse (battery to bus bar)
    • System is now live
    • Check voltage at bus bar (12.4V typical)
  2. Turn on DC-DC charger (if installed)
    • Start engine
    • Verify charging (LED indicator)
    • Check voltage rise on leisure battery
  3. Connect solar (if installed)
    • Controller should detect panels
    • Begin charging if sun available
  4. Test each 12V circuit individually:
    • Turn on one circuit
    • Verify device works
    • Check current draw
    • Turn off, move to next circuit
  5. Test inverter:
    • Turn on inverter
    • Check 230V output
    • Test with small load
    • Turn off
  6. Test 240V system (if installed):
    • Connect hookup (or turn on inverter)
    • Test RCD (press test button)
    • Test each socket
    • Verify earth bonding

Step 3: Load Testing

With system running:

Run everything simultaneously:

  • All lights on
  • Fridge running
  • Heater on (if winter)
  • Charge devices on USB
  • Inverter powering laptop

Monitor:

  • Battery voltage (should stay >12V under load)
  • Current draw (battery monitor)
  • Any hot cables (warning sign)
  • Any strange smells (burning = stop immediately)

My testing:

  • All loads on: 18A draw from battery
  • Battery voltage: 12.6V (stable)
  • No hot cables
  • All devices working correctly
  • Pass

Testing and Commissioning

Don’t skip this phase. Testing catches problems before they become failures.

Test 1: Polarity Verification

Every circuit:

  1. Set multimeter to DC voltage
  2. Measure at device:
    • Red probe to positive
    • Black probe to negative
    • Should read 12-14V
    • Reverse reading = wiring backwards (fix immediately)
  3. Check all circuits

Test 2: Voltage Drop Testing

For each circuit:

  1. Measure voltage at bus bar (source)
  2. Measure voltage at device (load) while running
  3. Calculate drop: Source voltage – Load voltage
  4. Should be <3%:
    • Example: 12.6V source, 12.3V load = 0.3V drop (2.4%, acceptable)

If voltage drop excessive:

  • Cable too thin (replace with thicker)
  • Poor connections (re-crimp)
  • Cable too long (reroute or upsize)

Test 3: Current Draw Verification

For each device:

  1. Check nameplate rating
  2. Measure actual current (clamp meter)
  3. Should match (within 10-20%)

Unexpected current:

  • Higher than rated: Possible fault, investigate
  • Much lower: May indicate problem or device not running full power

Test 4: Fuse Testing

Verify each fuse:

  1. Correct rating for circuit
  2. Actual continuity (multimeter)
  3. Properly seated in holder

Deliberately blow one fuse (use test fuse):

  • Verify system protects correctly
  • Fuse blows before cable damage
  • Replace with correct rating

Test 5: RCD Testing (240V)

Monthly requirement:

  1. Press RCD test button
  2. Should trip immediately (<30ms)
  3. Reset RCD
  4. If doesn’t trip: Replace RCD (it’s faulty)

Test 6: Earth Continuity (240V)

Every earth connection:

  1. Multimeter in continuity/resistance mode
  2. Test from earth pin of socket to chassis
  3. Should have very low resistance (<1Ω)
  4. High resistance = poor earth (fix immediately)

Test 7: Insulation Resistance

Professional test (optional but recommended):

Specialist insulation tester:

  • Tests cable insulation integrity
  • Detects hidden damage
  • Professional electrician can do this

Test 8: Load Profile Testing

Over 24 hours:

  1. Use van normally
  2. Monitor battery:
    • SOC at start
    • Daily consumption
    • Lowest SOC reached
  3. Verify calculations accurate:
    • Expected 70Ah use
    • Actual 72Ah use
    • Close enough

Test 9: Charging Testing

Each charging source:

Solar:

  • Verify current flow in sun
  • Check voltage regulation
  • Confirm controller settings

DC-DC:

  • Start engine
  • Verify charging begins
  • Check current matches rating

Hookup (if installed):

  • Connect to hookup
  • Verify charger activates
  • Check charging current

Test 10: Integration Testing

All systems together:

  • Charge from solar while using power
  • Charge from DC-DC while using power
  • Switch between hookup and inverter
  • Run maximum load safely

My testing lasted 3 days:

  • Day 1: Individual circuit tests
  • Day 2: Integration testing
  • Day 3: Real-world usage testing
  • Found 2 minor issues (loose connection, one fuse rating wrong)
  • Fixed and retested
  • System perfect since

Cable Management

Final phase. Makes maintenance easier and looks professional.

Step 1: Bundle Cables

Group cables logically:

  1. Power distribution (battery to bus bar)
  2. Each circuit (bus bar to device)
  3. Charging cables (solar, DC-DC)
  4. 240V cables (separate from 12V)

Bundling:

  • Cable loom (split conduit)
  • Cable ties every 30cm
  • Leave slack for service

Step 2: Secure Routing

Along van structure:

  • Use cable clips or saddles
  • Follow ribs or framework
  • Avoid movement areas

Through panels:

  • Grommets protect cables
  • Strain relief prevents pulling
  • Seal against water

My routing:

  • Main cables along passenger-side rib
  • Branch circuits to devices
  • All in split loom
  • Secured every 30cm
  • Looks tidy, easy to trace

Step 3: Labeling

Label at both ends:

  • Circuit origin (bus bar)
  • Circuit destination (device)
  • Cable size
  • Fuse rating

My labels:

  • “Lights Main – 10A – 2.5mm²”
  • “Fridge – 15A – 4mm²”
  • Clear, won’t rub off

Step 4: Access Points

Leave access for:

  • Fuse replacement
  • Connection inspection
  • Future circuit additions
  • Troubleshooting

Don’t bury cables where you can’t access them.

Step 5: Documentation

Create permanent record:

  1. Wiring diagram (laminated)
  2. Circuit list with:
    • Circuit name
    • Fuse rating
    • Cable size
    • Device location
  3. Component list
  4. Store in van

Future you will thank present you when troubleshooting in 2 years.

Troubleshooting

Common problems and solutions.

Problem: No Power at Device

Check:

  1. Main fuse installed?
  2. Circuit fuse blown? (check and replace)
  3. Switch on? (if switched circuit)
  4. Connections tight at bus bar?
  5. Connections tight at device?
  6. Cable damaged? (continuity test)

Problem: Fuse Keeps Blowing

Causes:

  1. Short circuit (cable damaged)
  2. Device faulty (drawing excess current)
  3. Fuse rating too low
  4. Cable too thin (overheating)

Diagnosis:

  • Disconnect device
  • Replace fuse
  • If fuse holds, device is faulty
  • If fuse still blows, short in cable

Problem: Low Voltage at Device

Causes:

  1. Voltage drop (cable too thin/long)
  2. Poor connections (high resistance)
  3. Battery depleted

Solutions:

  • Measure voltage at source and load
  • Calculate drop
  • Upsize cable if needed
  • Re-crimp connections
  • Charge battery

Problem: RCD Trips Immediately

Causes:

  1. Earth fault (cable damaged)
  2. Wet connections
  3. Faulty appliance

Diagnosis:

  • Disconnect all loads
  • Reset RCD
  • If trips, wiring fault
  • If holds, reconnect loads one by one
  • Trips when specific load connected = that load is faulty

Problem: Inverter Shuts Down Under Load

Causes:

  1. Battery voltage too low
  2. Overload (device draws more than inverter rated for)
  3. Cable too thin (voltage drop)
  4. Poor battery connections

Solutions:

  • Charge battery
  • Reduce load
  • Check cable size adequate
  • Tighten battery connections

Final Thoughts

I’ve installed four electrical systems over six years. The first took four weekends and had three major problems that required partial rewiring. The most recent took three days with zero issues.

The difference wasn’t skill or experience—it was methodology. The first system was “figure it out as I go.” The recent system was planned for a week before touching a wire. I drew diagrams, calculated every cable size, planned every route, prepared every tool. The installation itself was just executing the plan.

Here’s what I’ve learned: electrical installation rewards planning and punishes improvisation. The time spent planning (1 week) saved me three weekends of rework. The money spent on proper tools (£150) saved me from dangerous poor connections. The effort of proper testing (3 days) prevented failures that would’ve cost weeks of troubleshooting.

And please, don’t skip safety. Fuse everything. Use proper cable sizes. Test RCDs monthly. The £200 spent on protection could save your £30,000 van from fire. I’ve seen the aftermath of electrical fires in vans—they’re total losses. It’s not worth the risk.

My current system has been flawless for 14 months. It powers everything I need, charges reliably, and I’ve never once worried about safety. It cost £435 in materials and three days of work. That’s £17/month over 26 months for unlimited off-grid power. Worth every penny and every hour.

Now go plan your system properly, and actually follow the plan instead of improvising halfway through when you realize you forgot to buy ring terminals.

Where to Buy (UK Sources)

Cables:

  • 12V Planet: Quality automotive cable
  • Vehicle Wiring Products: Specialist auto electrical
  • Auto Marine Electrical: Marine/automotive grade

Components:

  • 12V Planet: Complete range, quality components
  • Blue Sea Systems: Premium marine (via chandleries)
  • Screwfix: Basic switches, consumer units
  • CPC Farnell: Wide range, technical specs

Tools:

  • Screwfix: Drills, basic tools
  • Amazon UK: Crimping tools, multimeters
  • RS Components: Professional test equipment

240V Components:

  • Screwfix: RCDs, consumer units, sockets
  • Toolstation: Similar to Screwfix
  • CEF (City Electrical Factors): Trade supplier

Specialist Van Components:

  • 12V Planet: Van-specific items
  • Carbest/Dometic: German quality (premium)
  • Various eBay sellers: Budget options

Continue Reading
By
Electrical & Off-Grid Power

Campervan Electrical Systems Explained (Complete Guide)

No Comments
Campervan Electrical Systems Explained (Complete Guide)

I’ve built electrical systems on four vans now. The first one was a disaster—undersized cables, no fusing, random wire colours, and a battery that lasted about 8 months before dying from constant over-discharge. The second was overengineered—£3,000 spent on components I didn’t need, could barely fit under the seat.

The forth system? Perfect. Well, not perfect. But it’s been running flawlessly for 26 months, cost £1,200, powers everything I need, and I understand every component and why it’s there.

Here’s what nobody tells you: electrical systems aren’t complicated if you understand the fundamentals. Voltage, current, resistance—that’s literally it. Everything else is just application of those three concepts. But people skip the fundamentals, jump straight to “what battery should I buy,” and end up with systems that don’t make sense.

I’ve made every mistake: mixed cable sizes, forgotten fuses, undersized batteries, oversized inverters, poor crimping, no battery monitoring, inadequate ventilation. Learn from my expensive education.

This is a complete guide to campervan electrical systems: the theory you need to understand why things work, the practical application for actually building systems, the calculations everyone avoids, and the mistakes that cost me plenty so they don’t cost you anything.

Table of Contents

  1. Electrical Fundamentals
  2. 12V vs 230V Systems
  3. Battery Technology
  4. Charging Sources
  5. Power Consumption
  6. System Design
  7. Wiring and Cables
  8. Fusing and Protection
  9. Distribution and Switching
  10. Monitoring
  11. Safety
  12. Common Mistakes
  13. Example Systems

Electrical Fundamentals

Right. If you don’t understand voltage, current, and resistance, you’ll struggle with everything else. Five minutes of theory saves hours of confusion.

Voltage (V)

What it is: Electrical pressure. Think of water pressure in pipes.

In vans:

  • 12V nominal (actually 11-14.6V depending on charge state)
  • 24V in some larger vehicles
  • 230V AC from inverter or hookup

Why it matters: Your devices need specific voltage. Wrong voltage damages equipment. A 12V fridge won’t work on 6V. A 12V LED on 24V will burn out.

Analogy: Voltage is like water pressure. Higher pressure pushes more water. Higher voltage pushes more electrons.

Current (A – Amps)

What it is: Flow rate of electricity. Like litres per minute of water.

In vans:

  • Small devices: 0.5-5A (LED lights, phone charging)
  • Medium devices: 5-20A (water pump, laptop charging, TV)
  • Large devices: 20-100A+ (inverter, diesel heater, fridge compressor)

Why it matters: Current determines cable size. High current needs thick cables. It also determines battery capacity needed.

Analogy: Current is flow rate. A trickle vs a fire hose. Both are water, but volume differs.

Resistance (Ω – Ohms)

What it is: Opposition to current flow. Like friction in pipes.

In vans:

  • Good conductors (copper wire): Very low resistance
  • Poor conductors: High resistance, generate heat
  • Fuses: Designed to have specific resistance

Why it matters: Resistance causes voltage drop and heat. Long, thin cables have high resistance. This wastes power and creates fire risk.

Analogy: Resistance is like pipe friction. Narrow pipes have more resistance than wide pipes.

Ohm’s Law: The Only Formula You Need

V = I × R

Where:

  • V = Voltage (volts)
  • I = Current (amps)
  • R = Resistance (ohms)

Rearranged:

  • I = V ÷ R (current equals voltage divided by resistance)
  • R = V ÷ I (resistance equals voltage divided by current)

Example: 12V LED drawing 1A

  • Resistance = 12V ÷ 1A = 12Ω

Power (W – Watts)

The formula: P = V × I

Where:

  • P = Power (watts)
  • V = Voltage (volts)
  • I = Current (amps)

Rearranged:

  • I = P ÷ V (current equals power divided by voltage)
  • V = P ÷ I (voltage equals power divided by current)

Example 1: 60W laptop charger at 12V

  • Current = 60W ÷ 12V = 5A

Example 2: 900W kettle at 230V

  • Current = 900W ÷ 230V = 3.9A

Example 3: 900W kettle through inverter at 12V

  • Inverter draws from 12V battery
  • Current = 900W ÷ 12V ÷ 0.9 (efficiency) = 83A
  • That’s why you need thick cables for inverters

Energy (Wh or Ah)

Watt-hours (Wh): Total energy used

Formula: Energy (Wh) = Power (W) × Time (hours)

Example: 60W laptop for 4 hours = 240Wh

Amp-hours (Ah): Energy at specific voltage

Conversion: Ah = Wh ÷ Voltage

Example: 240Wh at 12V = 20Ah

Why both measurements?

  • Watt-hours (Wh) is absolute energy
  • Amp-hours (Ah) is energy at specific voltage
  • Batteries are rated in Ah (at their voltage)
  • Devices are rated in W (watts)

Practical Application

Calculate current draw:

Device: 12V fridge rated 45W

  • Current = 45W ÷ 12V = 3.75A

Calculate daily energy:

Same fridge runs 8 hours per day

  • Energy = 45W × 8h = 360Wh
  • Or: 3.75A × 8h = 30Ah (at 12V)

Calculate battery size needed:

Daily consumption: 360Wh (30Ah at 12V) Want 3 days autonomy (no charging)

  • Total needed = 360Wh × 3 = 1,080Wh
  • At 12V = 90Ah minimum
  • Account for discharge limits (50% for lead-acid, 80% for lithium)
  • Lead-acid: 90Ah ÷ 0.5 = 180Ah battery
  • Lithium: 90Ah ÷ 0.8 = 112Ah battery (call it 120Ah)

This is how you size systems. Everything stems from these calculations.

12V vs 230V Systems

Understanding when to use 12V vs 230V saves money and improves efficiency.

12V DC System (Low Voltage)

What it is: Your van’s native electrical system. Battery voltage.

Voltage range:

  • Fully charged: 12.7-14.6V (charging)
  • Nominal: 12V
  • Discharged: 10.5-11V (stop using here)

Advantages:

  • Direct from battery (no conversion loss)
  • Efficient for 12V devices
  • Safe (low voltage won’t kill you)
  • Simple wiring
  • Standard automotive components

Disadvantages:

  • High current for given power (thick cables needed)
  • Limited device availability (not everything comes in 12V)
  • Voltage drop issues over distance

Best for:

  • LED lighting
  • Fans
  • Water pumps
  • 12V fridges/coolers
  • USB charging (via 12V adapters)
  • Diesel heaters
  • Anything designed for automotive use

230V AC System (Mains Voltage)

What it is: Household mains voltage. Requires inverter or hookup.

Voltage: 230V AC (50Hz in UK)

Sources:

  • Inverter (converts 12V DC to 230V AC)
  • Hookup at campsites
  • Generator (rare in vans)

Advantages:

  • Powers all household devices
  • Lower current for given power (thinner cables)
  • Familiar to everyone

Disadvantages:

  • Requires inverter (cost, efficiency loss 10-20%)
  • Dangerous voltage (can kill)
  • More complex wiring
  • RCD protection required

Best for:

  • Laptops (if no USB-C charging)
  • Kitchen appliances (blenders, toasters, kettles)
  • Power tools
  • Hair dryers
  • Anything that only comes in mains voltage

The Efficiency Argument

Example: Charging a laptop

Method 1: Inverter (12V → 230V → 19V)

  • Battery (12V DC) → Inverter (230V AC) → Laptop charger (19V DC)
  • Inverter efficiency: 85-92%
  • Laptop charger efficiency: 85-90%
  • Total efficiency: 72-83% (17-28% loss)

Method 2: 12V DC adapter (12V → 19V)

  • Battery (12V DC) → DC-DC adapter (19V DC)
  • Adapter efficiency: 88-94%
  • Total efficiency: 88-94% (6-12% loss)

Difference: Method 1 wastes 2-3× more power

Real numbers: 60W laptop, 4 hours daily

  • Inverter method: 288Wh from battery
  • DC adapter: 256Wh from battery
  • Savings: 32Wh daily = 960Wh monthly

On 200Ah battery (2,400Wh capacity), that’s 40% extra capacity recovered.

When to Use Each

Use 12V DC when:

  • Device available in 12V version
  • High-frequency usage (daily)
  • Efficiency matters (off-grid living)
  • Example: Fridge, lights, water pump, laptop (USB-C), phone charging

Use 230V AC when:

  • No 12V alternative exists
  • Occasional use only (efficiency loss acceptable)
  • High power (paradoxically easier—e.g., 2000W kettle via inverter uses thick cables but for 3 minutes only)
  • Example: Hair dryer, blender, power tools, toaster

My system: 90% is 12V DC. Inverter exists for occasional use (power tools, blender, guests’ laptop chargers). It’s off unless needed.

Hookup vs Off-Grid

Hookup (campsite mains):

  • Connect to 230V mains supply
  • Battery charger converts 230V → 12V (charges battery)
  • Can run 230V devices directly
  • Unlimited power (within campsite limits)

Off-grid (no hookup):

  • Battery powers everything
  • Solar/alternator recharge battery
  • Must manage power carefully
  • Inverter for 230V devices (if needed)

My reality: 95% off-grid. Hookup maybe 5 nights per year. System designed for off-grid, hookup is bonus.

Battery Technology

Your battery is the heart of your system. Choose wrong and everything else suffers.

Lead-Acid Batteries

Types:

  • Flooded: Traditional car batteries, require maintenance
  • AGM (Absorbed Glass Mat): Sealed, maintenance-free
  • Gel: Sealed, different chemistry

Advantages:

  • Cheap (£100-200 for 100Ah)
  • Available everywhere
  • Proven technology
  • Safe

Disadvantages:

  • Heavy (25-30kg for 100Ah)
  • Only 50% usable capacity (over-discharge damages them)
  • Short lifespan (500-1000 cycles)
  • Slow charging
  • Temperature sensitive
  • Require ventilation (hydrogen gas when charging)

Real capacity: 100Ah lead-acid battery

  • Only use 50Ah (50% discharge maximum)
  • Effective capacity: 50Ah

Lithium Batteries (LiFePO4)

Chemistry: Lithium Iron Phosphate (safest lithium variant)

Advantages:

  • 80-90% usable capacity
  • Lightweight (10-12kg for 100Ah)
  • Long lifespan (2000-5000 cycles)
  • Fast charging
  • Temperature tolerant
  • No maintenance
  • No ventilation needed

Disadvantages:

  • Expensive (£400-800 for 100Ah)
  • Requires BMS (Battery Management System)
  • Cannot charge below 0°C
  • Initial cost barrier

Real capacity: 100Ah lithium battery

  • Can use 80-90Ah safely
  • Effective capacity: 80-90Ah

Capacity Comparison

100Ah lead-acid (AGM):

  • Cost: £150-200
  • Weight: 28kg
  • Usable: 50Ah
  • Lifespan: 500-800 cycles
  • Cost per usable Ah per cycle: £0.0075/Ah/cycle

100Ah lithium (LiFePO4):

  • Cost: £500-700
  • Weight: 11kg
  • Usable: 85Ah
  • Lifespan: 3000-4000 cycles
  • Cost per usable Ah per cycle: £0.0020/Ah/cycle

Lithium is actually cheaper long-term. Plus weighs 1/3 as much.

My Experience

Van 1: 110Ah AGM lead-acid (£160)

  • Lasted 18 months (350-400 cycles)
  • Weight was 30kg
  • Usable capacity ~55Ah
  • Died from over-discharge (my fault, no monitoring)

Van 2: 200Ah lithium LiFePO4 (£680)

  • Still going after 26 months (600+ cycles)
  • Weight is 22kg
  • Usable capacity ~170Ah
  • No degradation noticed

Lithium paid for itself through longevity and better capacity. Would never go back to lead-acid.

Sizing Your Battery Bank

Formula: Daily consumption (Ah) × Days autonomy ÷ Usable capacity % = Battery size

Example 1: Weekend warrior

  • Daily use: 30Ah
  • Want 2 days autonomy
  • Lead-acid (50% usable)
  • Calculation: 30 × 2 ÷ 0.5 = 120Ah lead-acid

Example 2: Full-time living

  • Daily use: 70Ah
  • Want 3 days autonomy
  • Lithium (85% usable)
  • Calculation: 70 × 3 ÷ 0.85 = 247Ah lithium (call it 250Ah)

My system: 200Ah lithium

  • Daily use: 65-70Ah
  • Autonomy: 2-2.5 days (170Ah usable ÷ 70Ah daily)
  • Plus solar recharges daily (usually)
  • Perfect balance

Battery Location

Requirements:

  • Low in van (weight distribution, safety)
  • Ventilated (lead-acid) or sealed space okay (lithium)
  • Protected from damage
  • Accessible for connections
  • Temperature controlled (cold affects performance)

Common locations:

  • Under seating
  • Under bed
  • In front passenger footwell (single-seat conversions)
  • Dedicated battery box

My setup: Under passenger seat

  • Easy access
  • Low center of gravity
  • Protected by seat structure
  • Ventilated naturally

Battery Safety

Lead-acid:

  • Produces hydrogen when charging (explosive)
  • Requires ventilation to outside
  • Acid can leak if tipped (AGM less risk)
  • Vent cap maintenance (flooded type)

Lithium:

  • No gas production
  • BMS prevents overcharge/over-discharge
  • Fire risk if damaged (rare with LiFePO4)
  • Cannot charge below 0°C (BMS should prevent)

Protection needed:

  • Fusing on positive terminal
  • Secure mounting (won’t move in crash)
  • Ventilation (lead-acid)
  • BMS (lithium)
  • Temperature monitoring (optional but helpful)

Charging Sources

Your battery needs recharging. Three main sources.

Solar Charging

How it works: Panels convert sunlight to electricity, charge battery via controller.

Components:

  • Solar panels (£80-150 per 100W)
  • MPPT controller (£80-200)
  • Cables and mounting

Advantages:

  • Free energy
  • Silent
  • No engine running required
  • Enables off-grid living
  • Low maintenance

Disadvantages:

  • Weather dependent
  • Initial cost (£400-1,000)
  • Roof space required
  • Winter output is poor (UK)

Typical output (UK, 200W panels):

  • Summer: 60-80Ah daily
  • Winter: 15-25Ah daily
  • Overcast: 20-40Ah daily

When solar makes sense:

  • Off-grid living
  • Stationary camping (not driving daily)
  • Have roof space
  • Can afford initial investment

When solar doesn’t make sense:

  • Drive daily (alternator charges anyway)
  • Park in shade (trees, buildings)
  • Very high consumption (solar can’t keep up)
  • Tight budget (alternator charging cheaper)

Alternator Charging (DC-DC Charger)

How it works: Engine alternator charges starter battery. DC-DC charger takes power from starter battery, charges leisure battery safely.

Components:

  • DC-DC charger (£150-300)
  • Cables from starter to leisure battery
  • Fusing

Advantages:

  • Fast charging (20-60A typical)
  • Works while driving
  • Doesn’t drain starter battery
  • No roof space needed

Disadvantages:

  • Only charges while driving
  • Engine must run (fuel cost)
  • Initial cost (£200-400 installed)
  • Noise/pollution

Typical output: 30A DC-DC charger

  • 30 minutes driving = 15Ah
  • 1 hour driving = 30Ah
  • 2 hours driving = 60Ah

When DC-DC makes sense:

  • Drive frequently
  • Limited roof space
  • High consumption (need fast charging)
  • Cold climates (lithium heating)

When DC-DC doesn’t make sense:

  • Stationary for weeks
  • Trying to minimize driving
  • Have adequate solar
  • Tight budget (solar is better long-term)

My setup: 200W solar + 30A DC-DC

  • Solar covers 90% of needs
  • DC-DC is backup (drive 2-3× weekly)
  • Perfect combination

Split Charge Relay vs DC-DC Charger

Old method: Split charge relay

  • Simple switch connecting batteries when engine runs
  • Cheap (£20-40)
  • Works for lead-acid
  • Doesn’t work well for lithium
  • No charging optimization

Modern method: DC-DC charger

  • Proper battery-to-battery charger
  • Optimizes charging for battery type
  • Protects starter battery
  • Works with smart alternators
  • Supports lithium batteries

Use DC-DC charger. Split charge is outdated and problematic with modern vehicles.

Hookup (Mains Charging)

How it works: Plug into campsite 230V supply. Battery charger converts 230V → 12V, charges battery.

Components:

  • Battery charger (£50-200)
  • Hookup cable and inlet
  • RCD protection
  • Consumer unit

Advantages:

  • Unlimited power
  • Fast charging
  • Can run 230V devices directly
  • No sun/driving needed

Disadvantages:

  • Campsite cost (£10-30/night)
  • Not off-grid
  • Requires hookup facilities
  • Additional components (£150-300)

When hookup makes sense:

  • Mainly campsite camping
  • High consumption
  • Don’t want solar/DC-DC
  • Winter camping (solar insufficient)

When hookup doesn’t make sense:

  • Off-grid living
  • Wild camping focus
  • Already have solar/DC-DC

My usage: 5-10 nights per year

  • Emergency backup only
  • Mainly off-grid
  • Charger cost £80, barely used
  • Wish I’d skipped it

Combining Charging Sources

Best combination (what I run):

  • Solar (primary): 200W panels, daily charging
  • DC-DC (backup): 30A when driving
  • Hookup (rarely): Emergency only

Budget combination:

  • DC-DC only: 30-40A charger, drive 30+ mins daily
  • Cheapest if you drive regularly
  • No solar cost

Off-grid hardcore:

  • Solar (oversized): 400-600W panels
  • DC-DC (optional): Backup for winter
  • No hookup at all

Sizing guidelines:

If daily consumption is 50Ah:

  • Solar: 200-300W (summer coverage, winter struggles)
  • DC-DC: 30A (1-2 hours driving replaces daily use)
  • Or combination: 150W solar + 20A DC-DC

If daily consumption is 100Ah:

  • Solar: 400-600W (winter still struggles)
  • DC-DC: 40-60A (2-3 hours driving replaces daily use)
  • Combination recommended

Power Consumption

Understanding what uses power is essential for system sizing.

Measuring Consumption

Method 1: Nameplate ratings

  • Check device label for watts or amps
  • Calculate energy: Power × Hours used
  • Works for planning

Method 2: Actual measurement

  • Use DC clamp metre or power metre
  • Measure real consumption
  • More accurate (devices often use less than rated)

Typical Device Consumption

Lighting:

  • LED strip (1m): 4-6W
  • LED bulb: 3-8W
  • Halogen bulb (don’t use these): 10-20W

12V Devices:

  • Water pump: 30-60W (runs 5-15 mins daily)
  • Diesel heater fan: 10-25W (runs hours in winter)
  • MaxxFan vent: 5-40W (variable speed)
  • USB charging: 10-20W

Fridge/Cooling:

  • Compressor fridge: 40-60W (runs ~8h daily, cycles on/off)
  • Thermoelectric cooler: 40-50W (runs constantly, inefficient)
  • Coolbox: 30-40W

Computing:

  • Laptop: 30-65W (4-8 hours daily for remote work)
  • Tablet: 10-20W
  • Phone charging: 5-15W

230V via Inverter:

  • Hair dryer: 1000-2000W (5-10 mins)
  • Kettle: 900-2000W (3-5 mins)
  • Blender: 300-600W (2-5 mins)
  • Toaster: 800-1200W (3-5 mins)

Add inverter loss: Multiply by 1.15 for inefficiency

  • 1000W hair dryer = 1150W from battery

My Actual Daily Consumption

Summer day (no heating):

  • LED lighting: 15W × 4h = 60Wh (5Ah)
  • Fridge: 45W × 8h = 360Wh (30Ah)
  • Laptop: 60W × 4h = 240Wh (20Ah)
  • Phone charging: 15W × 2h = 30Wh (2.5Ah)
  • Water pump: 40W × 0.25h = 10Wh (0.8Ah)
  • Misc: 50Wh (4Ah)
  • Total: 750Wh (62.5Ah)

Winter day (heating needed):

  • Above items: 750Wh (62.5Ah)
  • Diesel heater: 20W × 6h = 120Wh (10Ah)
  • More lighting: 15W × 2h = 30Wh (2.5Ah)
  • Total: 900Wh (75Ah)

Heavy use day (working + cooking):

  • Above items: 750Wh
  • Laptop: 60W × 8h = 480Wh (40Ah)
  • Inverter for blender: 500W × 0.1h = 50Wh (4Ah)
  • Extra lighting: 50Wh (4Ah)
  • Total: 1,330Wh (110Ah)

Most days: 60-75Ah Heavy days: 90-110Ah (rare)

Calculating Your Consumption

Template:

DevicePower (W)Hours/DayDaily WhDaily Ah
Lights15W4h60Wh5Ah
Fridge45W8h360Wh30Ah
Laptop60W4h240Wh20Ah
Heating20W4h80Wh6.7Ah
Misc––50Wh4.2Ah
Total790Wh65.9Ah

Then:

  • Add 20% buffer: 65.9 × 1.2 = 79Ah
  • This is your daily consumption target
  • Size battery and charging for this

Reducing Consumption

Easy wins:

  1. LED lighting (not halogen): Saves 50-80% on lighting
  2. 12V fridge (not thermoelectric): 50% more efficient
  3. USB-C laptop charging (not inverter): Saves 15-20% on laptop power
  4. Good insulation (less heating needed): Saves 30-50% in winter

Behavioral changes:

  1. Laptop sleep mode when not typing: Saves 50% laptop power
  2. Switch off lights when leaving van: Obvious but forgotten
  3. Fridge temperature: Set to 4°C not 1°C (saves 20% power)
  4. Minimize inverter use: Only turn on when needed

My changes (reduced consumption 30%):

  • Switched to 12V charging for laptop (USB-C)
  • Better insulation (less heater runtime)
  • More efficient fridge (40W instead of 60W)
  • LED lights throughout

Went from 90Ah daily to 65Ah daily.

System Design

Bringing everything together into a coherent system.

Design Process

Step 1: Calculate consumption

  • List all devices
  • Estimate usage hours
  • Calculate daily Ah

Step 2: Size battery

  • Daily Ah × Days autonomy ÷ Usable %
  • Choose battery type (lithium recommended)

Step 3: Plan charging

  • Solar? Size for typical weather
  • DC-DC? Size for driving frequency
  • Hookup? Maybe, maybe not

Step 4: Calculate cable sizes

  • Maximum current per circuit
  • Cable length
  • Voltage drop calculation

Step 5: Plan distribution

  • Fused circuits
  • Switches for circuits
  • Monitoring points

Step 6: Safety protection

  • Fuses on all circuits
  • RCD for 230V
  • Battery protection

Example System 1: Weekend Warrior

Consumption: 30Ah daily Usage: Weekends, occasional week trips Driving: Yes, frequently

Battery: 100Ah lithium (£500)

  • Usable: 85Ah
  • Autonomy: 2.5 days

Charging: 30A DC-DC charger (£180)

  • 1 hour driving = 30Ah
  • No solar (saves £400)

Power distribution:

  • Lights: 10A circuit
  • Fridge: 10A circuit
  • USB charging: 15A circuit
  • Water pump: 15A circuit

Inverter: 600W (£100)

  • Occasional use only

Total cost: ~£950 (battery, DC-DC, fuses, cables, inverter)

Example System 2: Full-Time Off-Grid

Consumption: 70Ah daily Usage: Full-time, stationary weeks at a time Driving: Occasionally

Battery: 200Ah lithium (£680)

  • Usable: 170Ah
  • Autonomy: 2.4 days

Charging:

  • Solar: 300W (£380 with controller)
  • DC-DC: 30A backup (£180)

Power distribution:

  • Lights: 10A circuit
  • Fridge: 15A circuit
  • Laptop/USB: 20A circuit
  • Heater: 10A circuit
  • Water pump: 10A circuit
  • Misc: 10A circuit

Inverter: 1000W (£150)

  • Occasional use

Monitoring: Battery monitor (£120)

  • Essential for off-grid

Total cost: ~£1,850 (battery, solar, DC-DC, distribution, inverter, monitoring)

My System (Real-World)

Consumption: 65Ah daily average, 90Ah heavy days

Battery: 200Ah LiFePO4 (£680)

  • Usable: 170Ah
  • Autonomy: 2-2.5 days

Charging:

  • Solar: 200W Renogy (£220 panels, £100 controller)
  • DC-DC: 30A Renogy (£180)
  • Hookup: 20A charger (£80) – rarely used

Distribution:

  • Main bus bar with 6 fused circuits
  • Individual switches for lights, fridge, heater
  • Always-on circuit for battery monitor

Inverter: 1000W Renogy (£180)

  • Off unless needed
  • Switched

Monitoring: Victron SmartShunt (£130)

  • Tracks everything
  • Bluetooth to phone

Total cost: £1,570 (excluding labor)

Performance: Flawless for 26 months

  • Never run out of power (came close once in winter)
  • Solar covers 90% of charging
  • DC-DC used 2-3× weekly
  • Hookup maybe 5 nights in 2 years

Perfect balance for my usage.

Oversizing vs Undersizing

Oversizing (my first van):

  • 400W solar on van using 50Ah daily
  • Overkill, wasted £300
  • Battery fully charged by 11am, wasted rest
  • Heavy (extra panel weight)

Undersizing (mate’s van):

  • 100W solar, 100Ah battery, 80Ah daily use
  • Constantly struggling
  • Had to use hookup frequently
  • Frustrating

Right-sizing (current van):

  • 200W solar, 200Ah battery, 65Ah daily
  • Balanced
  • Occasional struggle in winter (expected)
  • Comfortable summer
  • Budget friendly

Guideline: Size for 80-90% coverage. Accept occasional shortage (drive, hookup, reduce usage). Don’t chase 100% coverage—expensive and wasteful.

Wiring and Cables

Get this wrong and you have fires. Get it right and you never think about it.

Cable Sizing Fundamentals

Why size matters:

  • Too thin: Overheats, fire risk, voltage drop
  • Too thick: Expensive, difficult to work with, unnecessary

Factors affecting sizing:

  1. Current: Higher current needs thicker cable
  2. Length: Longer runs need thicker cable
  3. Acceptable voltage drop: Usually 3% maximum
  4. Temperature: Hot environments need derating

Voltage Drop Calculation

Formula: Voltage drop (V) = (Current × Length × 2 × Resistance per m) ÷ 1000

Where:

  • Current in amps
  • Length in metres (one way)
  • ×2 for positive and negative
  • Resistance per m depends on cable size

Resistance per metre (copper cable at 20°C):

Cable SizeResistance (mΩ/m)
1.5mm²13.3
2.5mm²8.0
4mm²5.0
6mm²3.3
10mm²1.95
16mm²1.21
25mm²0.78
35mm²0.55

Example: 10A load, 5m cable run, 2.5mm² cable

  • Voltage drop = (10 × 5 × 2 × 8.0) ÷ 1000 = 0.8V
  • Percentage = 0.8V ÷ 12V = 6.7%
  • Too high! (target <3%)

Better: Same load, 4mm² cable

  • Voltage drop = (10 × 5 × 2 × 5.0) ÷ 1000 = 0.5V
  • Percentage = 0.5V ÷ 12V = 4.2%
  • Still high, but acceptable

Best: Same load, 6mm² cable

  • Voltage drop = (10 × 5 × 2 × 3.3) ÷ 1000 = 0.33V
  • Percentage = 0.33V ÷ 12V = 2.75%
  • Good!

Practical Cable Sizing Guide

For 12V systems:

CurrentLength <2mLength 2-5mLength >5m
Up to 5A1.5mm²2.5mm²4mm²
5-10A2.5mm²4mm²6mm²
10-20A4mm²6mm²10mm²
20-40A6mm²10mm²16mm²
40-60A10mm²16mm²25mm²
60-100A16mm²25mm²35mm²
100-150A25mm²35mm²50mm²

My system:

  • Lights (5A, 4m): 2.5mm²
  • Fridge (6A, 3m): 4mm²
  • Heater (3A, 2m): 2.5mm²
  • USB (10A, 2m): 4mm²
  • Inverter (100A, 0.5m): 25mm²
  • Battery to bus (60A, 1m): 16mm²

Cable Types

Automotive cable:

  • Stranded copper (flexible)
  • PVC insulation
  • Temp rated to 70-90°C
  • Use this for everything

NOT household wire:

  • Solid core (inflexible, breaks from vibration)
  • Lower temperature rating
  • Not suitable for vehicles

Marine/boat cable:

  • Tinned copper (corrosion resistant)
  • Expensive
  • Overkill for vans unless very humid environment

Solar cable:

  • UV resistant insulation
  • Double-insulated
  • Rated for outdoor use
  • Use for roof panel connections

Crimping and Connections

Methods:

1. Crimped connections (my preference)

  • Use proper crimping tool (£20-80)
  • Cable lug/terminal
  • Heat shrink over connection
  • Permanent, reliable

2. Soldered connections

  • Solder wire to terminal
  • Heat shrink over
  • Strong but more work
  • Can fail if joint flexes (vibration)

3. Screw terminals (temporary only)

  • Okay for testing
  • Not suitable for permanent installation
  • Can vibrate loose

4. Wago connectors

  • Push-in spring connectors
  • Quick and easy
  • Okay for low-current household
  • NOT suitable for vehicles (vibration)

Use crimping. It’s reliable, permanent, and vibration-resistant.

Crimping tips:

  1. Strip correct length (15mm typical)
  2. Insert fully into lug
  3. Crimp in correct tool position
  4. Tug test (should not pull out)
  5. Heat shrink over connection
  6. Label cable

Cable Routing

Best practices:

  1. Secure every 30cm with cable ties or clamps
  2. Protect through metal panels with grommets
  3. Keep away from heat sources (exhausts, heaters)
  4. Avoid water sources (sinks, roof leaks)
  5. Bundle cables in loom or conduit
  6. Label at both ends
  7. Leave slack for service (not guitar-string tight)
  8. Route positive and negative together (reduces electrical noise)

Where to route:

  • Along van ribs/structure
  • Behind panels/insulation
  • Under floor (if protected)
  • Through walls/bulkheads with grommets

My routing:

  • Main positive from battery through bulkhead to rear
  • Bus bar in rear electrical cabinet
  • Individual circuits from bus bar to devices
  • All cables in split-loom conduit
  • Secured every 30cm
  • Labeled at origin and destination

Fusing and Protection

This is safety. Don’t skip fuses.

Why Fuses Matter

Without fuse: Cable short → high current → heat → fire → van burns

With fuse: Cable short → high current → fuse blows → circuit disconnected → no fire

Fuses sacrifice themselves to protect cables and equipment.

Fuse Sizing

Formula: Fuse rating = Maximum circuit current × 1.25

Example: 10A load

  • Fuse = 10 × 1.25 = 12.5A
  • Use 15A fuse (next standard size up)

Cable must be rated for fuse current, not load current.

Example: 10A load, 15A fuse

  • Cable must handle 15A (the fuse won’t blow until 15A)
  • Use 2.5mm² minimum (rated 20A+)

Fuse Types

Blade fuses (automotive):

  • Mini: 2-30A
  • Standard: 3-40A
  • Maxi: 20-100A
  • Common, cheap, available everywhere
  • Use for loads <80A

ANL fuses (high current):

  • 30-500A range
  • Large format
  • Excellent for battery protection
  • Use for 80A+ circuits

MIDI fuses:

  • 30-150A
  • Compact
  • Good for medium-high current

My system:

  • Main battery: 100A ANL fuse
  • Inverter: 125A MIDI fuse
  • Individual circuits: 10-20A blade fuses

Fuse Locations

Critical rule: Fuse within 300mm of battery positive terminal

Why: If cable shorts before fuse, no protection. Cable from battery to fuse is vulnerable.

Every circuit needs fusing:

  • Battery to bus bar: One large fuse
  • Each circuit from bus bar: Individual fuse

My fusing:

  • Battery positive: 100A ANL fuse (30cm from terminal)
  • Bus bar to inverter: 125A fuse
  • Bus bar circuits: 6× blade fuses (10-20A each)

Circuit Breakers vs Fuses

Circuit breakers:

  • Resettable (flip switch)
  • More expensive
  • Bulky
  • Useful as switches AND protection

Fuses:

  • One-time use
  • Cheap
  • Compact
  • Pure protection

My choice: Fuses for protection, switches for switching. Clearer separation of functions.

RCD (Residual Current Device)

For 230V systems only (inverter or hookup):

What it does: Detects current imbalance (leakage to earth), trips instantly

Why essential: 230V can kill. RCD trips in milliseconds if you touch live wire.

Rating: 30mA trip current (standard for human protection)

Installation: After hookup inlet, before consumer unit

Cost: £30-60 for quality RCD

Do not skip RCD if you have 230V in your van. It saves lives.

Distribution and Switching

How you organize and control circuits.

Bus Bar System

What it is: Central point where circuits connect

Components:

  • Positive bus bar (fused circuits)
  • Negative bus bar (common ground)

Advantages:

  • Organized wiring
  • Easy to add circuits
  • Clear fusing
  • Professional appearance

My setup:

  • 12-way positive bus bar with blade fuse holders
  • Negative bus bar (unfused)
  • Mounted in electrical cabinet
  • All circuits radiate from here

Switches

Types:

Rocker switches:

  • Panel-mount
  • Illuminated or not
  • 10-20A typical
  • Good for permanent installations

Toggle switches:

  • Smaller footprint
  • Less intuitive
  • Cheaper
  • Good for secondary circuits

Push-button momentary:

  • For water pumps (press = run)
  • Not suitable for sustained loads

My switches:

  • Main circuits: Illuminated rocker switches on control panel
  • Inverter: Large rocker (accidentally left on is wasteful)
  • Water pump: Momentary push-button

Control Panel

Centralized switching:

Benefits:

  • All switches in one location
  • Know what’s on/off at a glance
  • Professional appearance
  • Easy to use

My control panel (3D printed + switches):

  • Row 1: Lights (3 zones), USB, Heater
  • Row 2: Fridge (always on), Inverter, Aux
  • Bottom: Battery monitor display

Takes 2 seconds to check what’s on.

Always-On vs Switched Circuits

Always-on (direct from battery):

  • Battery monitor
  • CO/smoke alarms
  • Fridge (if desired)
  • Emergency lighting

Switched (through control panel):

  • Main lighting
  • Heater
  • Water pump
  • Inverter
  • USB charging (maybe—I leave mine always-on)

Balance: Essential devices always-on, everything else switched.

Monitoring

You’re flying blind without monitoring. I learned this expensively.

Why Monitor?

Without monitoring:

  • Guess at battery state
  • Surprise dead battery
  • Over-discharge (damages battery)
  • No idea what’s using power
  • Can’t diagnose issues

With monitoring:

  • Know exact state of charge
  • See current draw in real-time
  • Track charging sources
  • Diagnose power hogs
  • Optimize usage

My first van: No monitoring

  • Over-discharged battery multiple times
  • Battery died after 18 months
  • Constant anxiety about power

Current van: Victron SmartShunt

  • Know exactly what’s happening
  • Never stressed about power
  • Battery health excellent after 26 months

Battery Monitors (Shunt-Based)

How they work:

  • Shunt measures every amp in/out
  • Counts amp-hours (coulomb counting)
  • Calculates state of charge

Accuracy: ±1-3% with quality monitors

Best monitors:

  • Victron SmartShunt: £120-140 (my choice)
  • Renogy 500A: £80-100 (good value)
  • BMV-712: £200-240 (display + Bluetooth)

Installation: Shunt on negative cable from battery. ALL negatives route through shunt.

Voltage Monitoring (Basic)

Cheaper option: Voltage display (£8-15)

Problems:

  • Voltage varies by load
  • Can’t determine accurate SOC
  • 12.4V could be 60% or 80% depending on conditions

Only useful: Very rough indicator

Don’t rely on voltage alone. Get proper battery monitor if you can afford it.

What to Monitor

Essential:

  • State of charge (%)
  • Voltage (V)
  • Current (A)
  • Remaining capacity (Ah)

Useful:

  • Power (W)
  • Time remaining (hours)
  • Historical data (Ah in/out)
  • Daily min/max values

Nice-to-have:

  • Temperature
  • Battery health
  • Charge cycles
  • Per-device consumption (requires multiple shunts)

My Victron app shows everything essential in real-time. I check it daily.

Safety

This section might save your life or van.

Fire Risks

Causes:

  1. Undersized cables (overheating)
  2. Poor connections (resistance → heat)
  3. No fusing (short circuits)
  4. Damaged insulation
  5. Overloading circuits

Prevention:

  • Proper cable sizing
  • Quality connections (crimped)
  • Fuse everything
  • Regular inspections
  • Avoid cheap components

Fire extinguisher: Mount one. ABC rated, 1-2kg. Near door. Check annually.

Electrical Shock

12V is safe: Can’t feel it, won’t hurt you

230V is dangerous: Can kill

Protection:

  • RCD on all 230V circuits
  • Double insulation on cables
  • Proper earth/ground
  • Professional installation (if unsure)

Procedure:

  • Never work on 230V live
  • Disconnect before maintenance
  • Verify dead with tester
  • Treat all 230V as live until proven otherwise

Gas Detection (Indirect Electrical Issue)

Why in electrical guide? Because electrical fires produce CO, and lithium batteries can produce toxic gases if damaged.

Install:

  • CO detector (carbon monoxide)
  • Smoke detector
  • Both mains/battery powered with backup
  • Test monthly

My setup:

  • Combined CO/smoke detector (hardwired to always-on circuit)
  • Battery backup
  • Located centrally, ceiling height

Hydrogen Gas (Lead-Acid)

Lead-acid batteries produce hydrogen when charging (explosive).

Requirements:

  • Ventilate to outside
  • No ignition sources near battery
  • Sealed battery box with vent
  • Never charge in sealed space

Lithium batteries: No hydrogen production, no venting needed.

Short Circuit Protection

Every circuit needs:

  1. Fuse appropriately sized
  2. Fuse close to battery (within 300mm)
  3. Cable sized for fuse rating
  4. Secure connections (won’t vibrate loose)

Check regularly:

  • Tighten connections (vibration loosens)
  • Inspect for damage
  • Look for heat discoloration
  • Verify fuses correct rating

Battery Safety

Lithium specific:

  • BMS prevents overcharge/over-discharge
  • Cannot charge below 0°C (BMS should prevent)
  • Fire risk if physically damaged (punctured)
  • Keep away from metal objects (short risk)

Lead-acid specific:

  • Acid can leak (corrosive)
  • Hydrogen gas (explosive)
  • Heavy (secure mounting essential)

General:

  • Fuse on positive terminal
  • Secure mounting (won’t move in accident)
  • Accessible for maintenance
  • Protected from physical damage

Common Mistakes

I’ve made all of these. Learn from my failures.

Mistake 1: Undersizing Battery

What I did: 110Ah AGM for 70Ah daily usage

  • Usable capacity: 55Ah (50% limit)
  • Couldn’t make it through one day
  • Constant over-discharge
  • Battery died in 18 months

Lesson: Size battery for 2-3 days autonomy, not just one day.

Mistake 2: No Fusing

What I did: First van had random circuits without fuses

  • “It’ll be fine”
  • Had a short circuit in LED strip
  • Cable overheated
  • Melted insulation
  • Caught it before fire (lucky)

Lesson: Fuse everything, without exception.

Mistake 3: Thin Cables

What I did: Used 2.5mm² for inverter (should be 25mm²)

  • 80A draw through 2.5mm² cable
  • Cable got hot enough to burn skin
  • Voltage drop was 2.8V (massive)
  • Inverter shut down from low voltage

Lesson: Calculate voltage drop, don’t guess cable sizes.

Mistake 4: Mixed Cable Colours

What I did: Used whatever cable I had

  • Black for positive, red for negative sometimes
  • Blue for some things
  • Caused confusion
  • Nearly wired things backwards

Lesson: Red = positive, black = negative, always. Buy proper colours.

Mistake 5: Poor Crimping

What I did: Used pliers instead of crimping tool

  • Connections looked okay
  • Vibration loosened them
  • Intermittent faults
  • High resistance = heat

Lesson: Buy proper crimping tool (£20-80). Worth every penny.

Mistake 6: No Monitoring

What I did: First van had voltage display only

  • Couldn’t tell real state of charge
  • Over-discharged battery multiple times
  • Battery sulfated (lead-acid damage)
  • Died after 18 months

Lesson: Invest in proper battery monitor. £100-150 saves £400+ battery.

Mistake 7: Oversized Inverter

What I did: Bought 2000W inverter for occasional laptop charging

  • Cost £250
  • Used maximum 100W
  • Wasted £150 vs 1000W inverter
  • Higher idle draw (waste power)

Lesson: Size inverter for actual needs + 25%, not “what if” scenarios.

Mistake 8: Cheap Components

What I did: Bought generic fuse holders (£3 vs £8)

  • Corroded within months
  • High resistance
  • Heat damage
  • Had to replace with quality units

Lesson: Buy quality for critical safety components. Fuse holders, cable lugs, terminals—don’t cheap out.

Mistake 9: No Labeling

What I did: Didn’t label cables

  • Six months later, needed to trace circuit
  • No idea which cable was which
  • Spent 2 hours tracing
  • Eventually used multimeter on every cable

Lesson: Label everything at both ends. Future you will thank present you.

Mistake 10: Ignoring Voltage Drop

What I did: Long thin cables to fridge (10m of 2.5mm², 6A load)

  • Voltage drop: 1.2V
  • Fridge saw 11.2V instead of 12.4V
  • Ran inefficiently
  • Compressor struggled

Lesson: Calculate voltage drop for every circuit. Keep drops under 3%.

Example Systems

Real-world system designs for different use cases.

System 1: Budget Weekend Warrior

Profile:

  • Weekend camping
  • Drives to sites (30+ mins)
  • Low power use
  • Budget: £800 max

Consumption: 30Ah daily

  • Lights: 10Ah
  • Phone charging: 5Ah
  • Water pump: 2Ah
  • Misc: 13Ah

Battery: 100Ah AGM (£150)

  • Usable: 50Ah
  • 1.5 days autonomy

Charging: 30A DC-DC charger (£180)

  • Driving charges battery
  • No solar (saves £300-400)

Distribution:

  • 4-way fuse box (£25)
  • 4 circuits: lights, pump, USB, aux

Inverter: 300W (£50)

  • Occasional use only

Monitoring: Voltage display (£12)

  • Basic but functional

Total: ~£650 (battery, DC-DC, distribution, inverter, cables)

Performance: Adequate for weekend use. Driving charges battery. No off-grid capability.

System 2: Full-Time Off-Grid

Profile:

  • Full-time living
  • Stationary weeks at a time
  • Moderate-high power use
  • Budget: £1,800

Consumption: 70Ah daily

  • Lights: 15Ah
  • Fridge: 30Ah
  • Laptop: 20Ah
  • Heater: 8Ah (winter)
  • Misc: 7Ah

Battery: 200Ah lithium (£680)

  • Usable: 170Ah
  • 2.4 days autonomy

Charging:

  • Solar: 300W (£380 total)
  • DC-DC: 30A (£180)
  • Hookup charger: 20A (£80)

Distribution:

  • 8-way bus bar (£40)
  • Switches for all circuits (£60)
  • Proper control panel

Inverter: 1000W (£150)

  • Regular use

Monitoring: Victron SmartShunt (£130)

  • Essential for off-grid

Total: ~£1,700 (battery, charging, distribution, inverter, monitoring)

Performance: Comfortable off-grid. Solar covers 85-90% of needs. DC-DC backup. Hookup emergency only.

System 3: Remote Worker

Profile:

  • Full-time living
  • High laptop usage
  • Moderate movement
  • Budget: £2,000

Consumption: 90Ah daily

  • Lights: 12Ah
  • Laptop: 45Ah (8 hours)
  • Fridge: 28Ah
  • Phone/tablet: 8Ah
  • Misc: 7Ah

Battery: 300Ah lithium (£980)

  • Usable: 255Ah
  • 2.8 days autonomy

Charging:

  • Solar: 400W (£520)
  • DC-DC: 40A (£220)

Distribution:

  • 10-way bus bar with monitoring (£60)
  • Control panel with switches (£80)

Inverter: 1000W (£150)

  • Daily use for laptop

Monitoring: Victron BMV-712 (£220)

  • Display + app

Extras:

  • USB-C PD outlets (£60) – efficient laptop charging

Total: ~£2,290 (over budget but worth it)

Performance: Handles high consumption. Large battery for cloudy days. Fast DC-DC for driving days. USB-C reduces inverter use.

My System (Reference)

Profile:

  • Full-time living
  • Remote work 3-4 days/week
  • Stationary with occasional driving
  • Built over time: £1,570 total

Consumption: 65Ah average, 90Ah heavy days

Battery: 200Ah lithium (£680)

Charging:

  • Solar: 200W (£320)
  • DC-DC: 30A (£180)
  • Hookup: 20A (£80)

Distribution:

  • 8-way bus bar (£35)
  • Control panel (£70)
  • All circuits switched

Inverter: 1000W (£180)

  • Switched off when not in use

Monitoring: Victron SmartShunt (£130)

Extras:

  • USB-C PD (£50)
  • Water pump (£40)
  • Switches/cables (£85)

Total: £1,570

Performance: Perfect for my use. Occasional winter struggles (expected). Solar covers 90% of charging. DC-DC used 2-3× weekly. Never run out of power (came close once in December).

Final Thoughts

I’ve built four electrical systems now. The first cost £450 and lasted 14 months before major issues (dead battery, unsafe wiring, no monitoring). The current system cost £1,570 and has been flawless for 26 months.

The difference wasn’t spending more money. It was understanding the fundamentals and making informed decisions. The first system was guesswork: “I need a battery… this one’s cheap… that’ll do.” The current system was calculated: “I use 70Ah daily… I need 200Ah lithium with 300W solar and 30A DC-DC backup.”

Here’s what I’ve learned: electrical systems aren’t complicated if you understand the basics. Calculate consumption honestly. Size battery for 2-3 days autonomy. Match charging to consumption. Use proper cables. Fuse everything. Monitor everything. It’s not difficult—it’s methodical.

The most common mistake isn’t technical—it’s skipping the planning phase. People buy components before understanding their needs. They end up with random incompatible parts that sort-of work but aren’t optimal. Spend a week planning before spending a pound on components.

And please, don’t skimp on safety. Proper fusing costs £30. A van fire costs everything. Proper cables cost £100 extra. Melted cables cost a rebuild. Quality crimping tool costs £50. Poor connections cost intermittent faults and frustration. The savings aren’t worth it.

My £1,570 system powers laptop work, fridge, heating, lighting, cooking, and charging for unlimited off-grid living (9-10 months yearly in UK). That’s £60/month if I keep the van 2 years, £31/month over 4 years. Considering I’d spend £10-20/night on campsite hookup, the system paid for itself in months.

Now go calculate your actual consumption, size your system properly, and build something that works instead of cobbling together random components and hoping for the best.

Further Resources

Books:

  • “The 12 Volt Bible for Boats” (Miner/Maloney) – ignore boat-specific bits, fundamentals apply
  • “RV Electrical Systems” (Bill Moeller) – comprehensive but American-focused

Websites:

  • 12V Planet guides (www.12vplanet.co.uk/guides)
  • Victron community forums (community.victronenergy.com)
  • HandyBob’s Blog (handybobsolar.wordpress.com) – technical, American, but excellent

YouTube:

  • DIY Solar Power with Will Prowse (American but good fundamentals)
  • Victron Energy Official (product-specific but educational)
  • Natures Generator (various builds and troubleshooting)

Calculators:

  • Voltage drop: www.calculator.net/voltage-drop-calculator.html
  • Battery sizing: Various van conversion sites
  • Cable sizing: automotive wiring charts

Where to learn:

  • Online electrical courses (not specific to vans but teach fundamentals)
  • Ask experienced van builders (forums, Facebook groups)
  • Experiment on test bench before installing in van

Where to Buy (UK Sources)

Batteries:

  • Lithium: Fogstar, Alpha Battery, Roamer, Power Queen (all on Amazon/direct)
  • Lead-acid: Tayna, local automotive suppliers

Charging:

  • Solar: Renogy UK, 12V Planet, Bimble Solar, Amazon UK
  • DC-DC: Renogy, Victron, Sterling (12V Planet, Amazon)
  • Chargers: Victron, CTEK, Ring (Amazon, specialist suppliers)

Components:

  • Cable: 12V Planet, Vehicle Wiring Products, Auto Marine Electrical
  • Fuses/distribution: 12V Planet, Blue Sea Systems (marine suppliers)
  • Terminals/lugs: Vehicle Wiring Products, RS Components

Monitoring:

  • Victron: 12V Planet, Amazon UK, Victron dealers
  • Renogy: Renogy UK, Amazon UK
  • Generic: Amazon UK (quality varies)

Tools:

  • Crimping tools: Engineer PA-09 (Amazon), generic hydraulic crimpers
  • Multimeters: Fluke (expensive but worth it), UNI-T (budget but decent)
  • Cable strippers: Klein, Knipex, Weidmüller

Continue Reading
By
Solar Power Systems

How to Install a Campervan Solar System

No Comments
How To Install A Campervan Solar System

I’ve installed solar on four vans now. The first installation took me 11 hours, involved three trips to the hardware shop for parts I’d forgotten, and resulted in a small roof leak that took two days to discover. The fourth installation took 6 hours start to finish with zero leaks and perfect cable management.

The difference? Understanding where the difficult bits actually are, having the right tools ready, and knowing which steps you absolutely cannot skip (spoiler: it’s the ones involving sealant and testing).

Here’s what nobody tells you: drilling holes in your van roof is genuinely nerve-wracking the first time. You’ll second-guess yourself constantly. That’s normal. But if you follow proper procedures, use correct sealant, and test everything before final assembly, it’s actually difficult to cock it up badly.

I’ve made every mistake you can make: forgotten to prime bolt holes (rust developed), used bathroom silicone instead of marine sealant (failed after 8 months), didn’t test before sealing (had to reopen everything), and mounted panels in stupid locations (shade from roof vent). Learnt from my failures.

This is a complete, step-by-step guide to installing campervan solar system: the planning nobody does properly, the tools you actually need, the techniques that prevent leaks, and the testing procedures that catch problems before they’re sealed forever.

Table of Contents

  1. Planning Your Installation
  2. Tools and Materials
  3. Pre-Installation Testing
  4. Roof Preparation
  5. Panel Mounting
  6. Cable Entry and Routing
  7. Controller Installation
  8. Battery Connections
  9. System Testing
  10. Troubleshooting
  11. Maintenance

Planning Your Installation

Don’t skip this. Seriously. I’ve watched people start drilling before measuring properly. It always ends badly.

Step 1: Measure Your Roof Space

You’ll need:

  • Tape measure
  • Paper and pencil
  • Masking tape

Process:

  1. Measure total roof dimensions (length × width)
  2. Mark obstacles with masking tape:
    • Roof vents (measure their footprint)
    • Roof rack mounting points
    • Antenna mounts
    • Anything protruding from roof
  3. Identify curved areas (edges where roof curves down). These are unusable for rigid panels.
  4. Measure usable flat area remaining after obstacles
  5. Draw to scale on paper (1:20 scale works well)
    • Example: 1cm on paper = 20cm on roof

My van example (VW Transporter):

  • Total roof: 4.9m × 1.9m
  • Roof vents: Two vents (60cm × 50cm each)
  • Roof bars: Four mounting points
  • Curved edges: ~25cm around perimeter
  • Usable area: 6.8m² approximately

Step 2: Plan Panel Layout

Cut paper rectangles to scale representing your panels.

Standard 100W panel: ~120cm × 55cm Standard 150W panel: ~150cm × 67cm

Considerations:

  1. Shadow mapping: Will roof vent cast shadow? At what times of year? Low winter sun creates longer shadows—stand back and visualize sun angles.
  2. Cable routing: Panels need to connect. Plan which panels wire together and where cables run.
  3. Cable entry point: Where do cables enter van? Near which panel? This determines layout.
  4. Access for maintenance: Can you reach all junction boxes for future maintenance?
  5. Airflow: Leave some gaps between panels and roof (mounting brackets provide this).

My layout (2× 100W panels):

  • Both panels landscape orientation
  • 10cm gap between panels (cable routing)
  • Positioned to minimize shade from front roof vent
  • Cable entry through rear roof vent
  • Junction boxes face inward (accessible from gap)

I spent 2 hours playing with paper rectangles. This prevented mounting panels in locations that would’ve been shaded or had difficult cable routing.

Step 3: Mark Panel Positions

Once layout is finalized:

  1. Transfer measurements to roof using masking tape
    • Mark panel corners
    • Mark mounting bracket positions
    • Mark cable routing paths
  2. Double-check shadows in late afternoon (low sun angle simulates winter)
  3. Verify roof vent clearance (measure twice)
  4. Check mounting bracket positions don’t hit roof structure
    • Feel underneath headliner
    • Ensure brackets mount to solid roof, not just skin
  5. Take photos of marked layout (reference during installation)

Step 4: Identify Cable Entry Point

Three main options:

Option A: Through existing roof vent

  • Advantages: No new holes, easy routing
  • Disadvantages: Limited by vent location
  • Best for: Most people

Option B: New cable gland

  • Advantages: Place cables wherever needed
  • Disadvantages: Extra hole to drill and seal
  • Best for: Professional installations or when vent routing impossible

Option C: Through existing penetrations (antenna holes, etc.)

  • Advantages: No new holes
  • Disadvantages: Limited locations, may require removing fixtures
  • Best for: Specific circumstances

I use Option A (through roof vent). It’s the easiest and least risky method.

Step 5: Plan Wiring Route Inside Van

Before you start:

  1. Trace path from cable entry to controller location
    • How do cables run?
    • Through walls? Along roof liner?
    • Behind panels?
  2. Measure cable length needed
    • Actual route length (not straight line)
    • Add 1m extra for connections and mistakes
    • Round up to next whole metre
  3. Plan controller location
    • Near battery (minimize high-current cable runs)
    • Accessible for monitoring
    • Protected from moisture
    • Visible if controller has display
  4. Plan battery location (if not already installed)
    • Low in van (weight distribution)
    • Ventilated space (especially lead-acid)
    • Accessible for maintenance
    • Protected from damage

My setup:

  • Cables enter through rear roof vent
  • Run along roof liner edge (hidden)
  • Drop down rear wall behind furniture
  • Controller mounted on rear wall
  • 0.5m cable run from controller to battery
  • Total cable run: 6m from panels to controller

Safety Planning

Before touching tools:

  1. Check weather forecast (dry day for installation—moisture kills sealant adhesion)
  2. Plan for leaks (have tarp ready if weather turns)
  3. Disconnect battery during electrical work (prevents shorts)
  4. Have fire extinguisher accessible (lithium battery safety)
  5. Work with someone if possible (passing tools to roof, safety spotter)

Tools and Materials

Here’s what you actually need. I’ve listed essentials vs nice-to-have.

Essential Tools

Drilling and mounting:

  • Cordless drill (12V+ minimum, 18V better)
  • Drill bit set: 2mm, 3mm, pilot sizes, final bolt sizes (6mm, 8mm typical)
  • Step drill bit (optional but brilliant for clean holes)
  • Deburring tool or round file
  • Tape measure
  • Spirit level
  • Pencil/marker
  • Masking tape
  • Centre punch (marks drill locations accurately)

Electrical:

  • Wire strippers (essential for clean cable prep)
  • Crimping tool (for cable terminals)
  • Soldering iron + solder (optional, but I prefer soldered connections)
  • Multimeter (absolutely essential for testing)
  • Screwdrivers (Phillips and flathead, various sizes)
  • Spanner set (for bolt tightening)
  • Cable cutters (for thick solar cable)

Sealant application:

  • Sealant gun (for Sikaflex tubes)
  • Disposable gloves (sealant is sticky and difficult to clean)
  • Paper towels/rags
  • Isopropyl alcohol (90%+, for cleaning)
  • White spirit (for cleaning uncured Sikaflex)

Essential Materials

Mounting hardware:

  • Mounting brackets (depends on panel and mounting method)
  • Stainless steel bolts (M6 or M8 typical, 30-40mm length)
  • Stainless steel washers (large diameter for load spreading)
  • Stainless steel nylock nuts (prevent loosening from vibration)
  • Backing plates (aluminum or stainless, for inside roof)

Sealant:

  • Sikaflex 252 or 521UV (proper marine sealant, £15-20 per tube)
  • NOT bathroom silicone (will fail)
  • NOT cheap sealant (will fail)
  • Buy 2-3 tubes (you’ll use more than expected)

Cables:

  • Solar cable: 4-6mm² for most systems (buy 10-20% extra)
  • Battery cable: 16-25mm² for controller to battery (high current)
  • Cable glands (if drilling new holes)
  • MC4 connectors (for panel connections)
  • Cable ties (UV-resistant)
  • Heat shrink tubing (various sizes)

Electrical:

  • Inline fuses + holders (solar: 15-20A, battery: 30-60A depending on system)
  • Cable lugs (for battery connections)
  • Junction box (if splitting solar array)

Protection:

  • Primer (rust prevention for drilled holes)
  • Touch-up paint (match van color)
  • Cable sleeve/loom (protects cables from chafing)

Nice-to-Have Tools

  • Torque wrench (proper bolt tensioning)
  • Right-angle drill attachment (tight spaces)
  • Inspection mirror (see behind panels)
  • Endoscope camera (check roof structure before drilling)
  • Cable tracer (for routing inside walls)

What I Actually Use

My essential toolkit:

  • DeWalt 18V drill (overkill, but I own it)
  • Basic drill bit set
  • Step drill bit (makes clean holes easily)
  • Klein wire strippers
  • Engineer PA-09 crimping tool
  • Fluke multimeter (cheaper ones are fine)
  • Wera screwdriver set
  • Sikaflex 252 (3 tubes for complete installation)
  • Standard socket set

Total tool cost (if buying new): £150-250 If you own basic tools already: £50-80 for solar-specific items

Pre-Installation Testing

Test everything before mounting. I learned this the hard way.

Test 1: Panel Output Verification

Before mounting panels:

  1. Connect multimeter to panel output
    • Red probe to positive (usually marked red wire)
    • Black probe to negative (usually black wire)
    • Set meter to DC voltage
  2. Measure open-circuit voltage (Voc)
    • In bright sunlight
    • Panel disconnected from everything
    • Should read 18-22V for “12V” panel (this is normal)
    • Should read 36-44V for two 100W panels in series
  3. Check current output
    • Set meter to DC amps (10A+ range)
    • Connect meter in series with panel and a load (or short circuit briefly)
    • Should read close to panel rating (5-6A for 100W panel)
    • Do this quickly (under 5 seconds—sustained short circuit can damage cells)
  4. Verify polarity
    • Positive should be positive
    • Negative should be negative
    • Mark with tape if not clearly labeled

If panels don’t produce expected voltage/current:

  • Check in full sun (not cloudy)
  • Ensure panel isn’t shaded at all
  • Verify multimeter is working (test on known voltage)
  • If still wrong, panel may be faulty (return before installation)

Test 2: Controller Function Test

Before mounting controller:

  1. Connect controller to battery
    • Follow polarity carefully (wrong polarity kills controllers)
    • Use appropriate cable size (see controller manual)
    • Include inline fuse on positive cable
  2. Controller should power up
    • Display lights up (if it has display)
    • LEDs indicate status
    • No error codes
  3. Connect panel to controller
    • Verify correct polarity
    • Controller should detect panel voltage
    • Should show “charging” or “waiting” status
  4. Monitor charging current
    • Should show amps flowing to battery
    • Verify current matches expectations (panel rating minus losses)

If controller doesn’t work:

  • Verify battery voltage (should be 11-14V for 12V system)
  • Check all connections are tight
  • Verify fuses aren’t blown
  • Check polarity (triple check)
  • Consult controller manual troubleshooting section

Test 3: Cable Continuity Test

For each cable before installation:

  1. Set multimeter to continuity mode (beep setting)
  2. Touch probes to both ends of same conductor
  3. Should beep (indicating continuous circuit)
  4. Test both positive and negative
  5. Test for shorts between positive and negative (should NOT beep)

This catches damaged cables before installation. I’ve had cables with internal breaks that looked fine externally—continuity testing found them.

Roof Preparation

This is critical. Surface prep determines whether your installation lasts 2 months or 20 years.

Step 1: Clean Roof Thoroughly

You need:

  • Degreaser or strong detergent
  • Scrubbing brush
  • Hose or buckets of water
  • Isopropyl alcohol 90%+
  • Clean rags/cloths

Process:

  1. Wash entire roof with degreaser
    • Remove all dirt, dust, debris
    • Pay attention to mounting areas
    • Rinse thoroughly
  2. Dry completely
    • Chamois or microfiber cloths
    • Ensure no water remains
    • Wait 1-2 hours in sun if necessary
  3. Final clean with isopropyl alcohol
    • Wipe mounting areas only
    • This removes any remaining oils/residues
    • Let evaporate completely (2-3 minutes)

Critical: Don’t install if roof is damp. Sealant won’t adhere properly. I’ve had sealant fail because I rushed this step—installed same day as washing. Bad move.

Step 2: Mark Hole Locations

Transfer your planned layout to roof:

  1. Place brackets in planned positions
  2. Mark mounting holes with pencil
    • Through bracket holes
    • Mark center of each hole clearly
    • Double-check measurements
  3. Verify positions with tape measure
    • Check distances match plan
    • Ensure brackets are square
    • Confirm clearance from roof furniture
  4. Use centre punch to mark hole centers
    • Creates small dimple
    • Prevents drill bit wandering
    • Mark all holes before drilling any

Step 3: Verify No Obstructions

Before drilling, check underneath:

  1. Feel inside van at marked locations
    • Is there solid roof structure?
    • Any wiring/pipes in the way?
    • Enough space for backing plates?
  2. Use endoscope camera if available
    • Check roof structure
    • Identify any hidden obstacles
    • Confirm thickness of roof material
  3. Check for double-skinned areas
    • Some vans have double-layer roofs
    • Mark if you’ll drill through two layers
    • May need longer bolts

My mistake: Drilled into double-layer roof with too-short bolts. Had to buy longer bolts and redrill slightly offset. Check first.

Step 4: Prepare Paint/Primer

You’ll need:

  • Rust-preventative primer (Rustoleum or similar)
  • Touch-up paint matching van color (optional)
  • Small brush

Have these ready before drilling. You want to prime holes immediately after drilling to prevent rust starting.

Panel Mounting

This is where you commit. Deep breath. You’ve planned properly. It’ll be fine.

Step 1: Drill Pilot Holes

Start small:

  1. Select 2-3mm drill bit
  2. Drill first pilot hole
    • Start perpendicular to surface
    • Drill slowly at first (prevents bit wandering)
    • Feel for any changes in resistance (might indicate hitting structure)
    • Drill through completely
  3. Check from inside
    • Verify hole is where expected
    • Ensure no damage to interior
    • Confirm spacing
  4. If first hole is good, drill remaining pilots

Why pilot holes?

  • Easier to correct mistakes (small holes are easier to seal than large ones)
  • Prevents bit wandering on final drilling
  • Lets you verify positioning before committing

Step 2: Drill Final Holes

Enlarge to bolt size:

  1. Select correct size bit for your bolts
    • M6 bolts: 6.5mm hole
    • M8 bolts: 8.5mm hole
    • Slightly oversized allows bolt insertion
  2. Drill slowly
    • Let drill do the work
    • Don’t force it
    • Keep bit perpendicular
  3. Deburr holes immediately
    • Use deburring tool or round file
    • Remove sharp edges (prevents cable damage and corrosion)
    • Both inside and outside

Step drill bit alternative:

  • Creates cleaner holes with less effort
  • Self-deburrs as it cuts
  • More expensive (£15-25) but worth it
  • I use step bits for all roof drilling now

Step 3: Prime and Seal Holes

Immediately after drilling:

  1. Blow out metal shavings (compressed air or breath)
  2. Apply rust-preventative primer to bare metal
    • Inside hole edges
    • Let dry 5-10 minutes
    • Essential for preventing rust
  3. Optional: touch-up paint on exterior
    • Matches van appearance
    • Additional rust protection
    • Purely cosmetic but nice

I learned this the hard way. Didn’t prime bolt holes on first installation. After 10 months, visible rust around bolts. Had to remove panels, clean rust, reprime, reinstall.

Step 4: Apply Sealant to Brackets

This is critical:

  1. Put on disposable gloves (Sikaflex is sticky)
  2. Apply sealant to bracket underside
    • Continuous bead around perimeter
    • Cover all edges
    • Don’t skimp (excess will squeeze out—this is good)
  3. Apply sealant to bolt threads
    • Each bolt gets coating
    • This seals bolt shaft
    • Prevents water wicking down threads

Sikaflex 252 vs 521UV:

  • 252: General marine sealant, excellent adhesion
  • 521UV: Better UV resistance, same adhesion
  • Both work excellently
  • I use 252 (slightly cheaper)

Step 5: Mount Brackets

Work quickly (Sikaflex skins over in 10-30 minutes):

  1. Position bracket over holes
  2. Insert bolts from outside
    • Through bracket
    • Through roof
    • Sealant on threads will seal as you insert
  3. Inside van: add backing plate
    • Spreads load
    • Prevents roof crushing
    • Large washer works if no backing plate
  4. Add washer and nylock nut
  5. Tighten bolts
    • Snug, not crushing
    • Excess sealant should squeeze out (good sign)
    • Uniform tightness on all bolts

Tightening sequence (for 4-bolt bracket):

  • Tighten opposite corners first (1, then 3, then 2, then 4)
  • This prevents bracket warping
  • Final tighten in same sequence

Step 6: Clean Excess Sealant

While still wet:

  1. Remove excess squeezed-out sealant
    • Paper towel for bulk
    • White spirit on rag for cleanup
    • Don’t remove all—leave slight bead at edges
  2. Clean bolt heads and bracket surfaces
  3. Inspect seal
    • Should be continuous around bracket
    • No gaps
    • Slight bead of sealant visible

Let cure 24-48 hours before mounting panels or driving. Sikaflex needs time to cure fully.

Step 7: Mount Panels to Brackets

After sealant has cured:

  1. Position panel on brackets
    • Usually 4 bolts per panel (one per corner)
    • Align mounting holes
  2. Insert bolts with washers
    • Stainless steel bolts
    • Washers prevent crushing panel frame
    • Spring washers prevent loosening
  3. Tighten bolts
    • Snug, not excessive
    • Panels should be secure but not deformed
    • Check tightness periodically (vibration can loosen)

Panel orientation:

  • Junction box accessible (for future maintenance)
  • Cable routing direction considered
  • Frame mounting holes aligned with brackets

Cable Entry and Routing

This determines how clean your installation looks and functions.

Method 1: Through Roof Vent (Recommended)

My preferred method:

  1. Remove roof vent assembly
    • Usually 4-6 screws
    • Carefully lift out
    • Note how it reassembles
  2. Identify cable routing path
    • Down vent housing
    • Or along edge of vent opening
    • Avoid moving parts (vent mechanism)
  3. Drill small hole for cables
    • In vent housing or frame
    • 12-16mm hole for typical solar cables
    • Deburr thoroughly
  4. Install cable gland
    • Proper watertight gland (£5-8)
    • Seal with small amount of Sikaflex
    • Tighten compression fitting
  5. Route cables through gland
  6. Reinstall roof vent
    • Check seal is intact
    • Test vent operation
    • Verify cables don’t interfere

Method 2: New Cable Gland

If vent routing isn’t feasible:

  1. Select location for gland
    • Near panels
    • Accessible from inside
    • Solid roof structure
  2. Drill hole (size depends on gland)
    • Usually 12-20mm
    • Deburr carefully
  3. Prime hole (rust prevention)
  4. Install cable gland
    • Apply Sikaflex to gland base
    • Insert from outside
    • Secure inside with nut
    • Tighten compression fitting around cables

Cable glands: Buy proper marine/automotive rated glands. Cheap ones leak.

Panel Wiring on Roof

Series connection (my setup):

  1. Connect panel 1 positive to panel 2 negative
    • Use MC4 connectors (solar panels usually come with them)
    • Simply plug together
    • Verify connection is secure
  2. Run remaining wires to cable entry
    • Panel 1 negative = array negative
    • Panel 2 positive = array positive
    • These run to controller

Parallel connection:

  1. Use junction box on roof
    • All positives connect together
    • All negatives connect together
    • Weatherproof box essential
  2. Single cable pair runs from junction box to controller

Cable Routing Inside Van

Best practices:

  1. Use cable loom or sleeve
    • Protects cables from chafing
    • Professional appearance
    • UV protection
  2. Secure every 30-50cm
    • UV-resistant cable ties
    • Avoid sharp bends (radius > 10× cable diameter)
    • Keep away from hot surfaces
  3. Label cables
    • “Solar Positive”, “Solar Negative”
    • Future you will thank present you
  4. Avoid high-traffic areas
    • Don’t route under carpets or panels that flex
    • Keep away from water sources
    • Protect from physical damage

My routing (VW Transporter):

  • Entry through rear roof vent
  • Along roof liner edge (behind trim)
  • Down rear pillar (behind plastic panel)
  • To controller on rear wall
  • Total length: 6m

Controller Installation

Where you put the controller matters.

Choosing Controller Location

Ideal location:

  • Near battery (minimize high-current cable length)
  • Dry area (protected from moisture)
  • Accessible for monitoring
  • Visible if controller has display
  • Ventilated (controllers generate heat)

My location: Rear wall of van, 0.8m from battery, protected by furniture.

Mounting Controller

Most controllers have mounting holes:

  1. Mark mounting holes on wall
    • Use spirit level (controller should be level)
    • Mark with pencil
    • Verify clearance for cables
  2. Drill pilot holes
    • Appropriate for your wall material
    • Wood: 2-3mm pilot
    • Metal: 3-4mm pilot
  3. Mount controller with screws
    • Stainless steel screws
    • Washers for load spreading
    • Ensure controller is secure

Cable access:

  • Cables enter from bottom (prevents drips entering controller)
  • Leave slack for future service
  • Don’t over-tighten cable glands (if controller has them)

Wiring Controller to Solar Panels

Always connect battery BEFORE solar panels (prevents voltage spike damage).

  1. Route solar cables to controller
  2. Strip cable ends (10-15mm of insulation)
  3. Insert into controller solar terminals
    • Usually marked “SOLAR+” and “SOLAR-“
    • Polarity is critical (verify with multimeter if unsure)
    • Tighten terminal screws securely
  4. Verify connection
    • Gentle tug test (should not pull out)
    • Check no bare wire exposed outside terminal

Installing Solar Fuse

Fuse goes on positive cable between panels and controller:

  1. Calculate fuse rating
    • Panel short-circuit current × 1.25 = fuse rating
    • Example: 6A panel current × 1.25 = 7.5A, use 10A fuse
  2. Install inline fuse holder
    • Within 30cm of panel connection
    • Accessible (you may need to replace fuse)
    • Waterproof fuse holder for roof installations
  3. Insert fuse
    • Correct rating
    • Quality fuse (not cheap glass fuses that vibrate and break)

My setup: 15A blade fuse in waterproof holder, 20cm from cable entry point.

Battery Connections

High current connections. Take care here.

Safety First

Before connecting:

  1. Verify all connections upstream are correct
    • Solar panels connected properly
    • Controller wired correctly
    • Fuses in place
  2. Double-check polarity (wrong polarity damages controllers and batteries)
  3. Disconnect any loads from battery temporarily
  4. Wear eye protection (battery connections can spark)

Battery Cable Sizing

Controller to battery requires thick cable:

  • 200W system: 16mm² cable minimum
  • 300W system: 25mm² cable
  • 400W+ system: 35mm² cable

Why so thick?

Solar controllers can deliver 30-60A to batteries (MPPT controllers especially). Thin cables overheat and drop voltage.

My setup: 200W system, 25mm² cable (0.5m run from controller to battery). Overkill but safe.

Cable Preparation

  1. Cut cables to length (measure actual route, add 0.5m slack)
  2. Strip 15mm insulation from ends
  3. Crimp cable lugs
    • Use proper crimping tool
    • Crimp is permanent (should be impossible to pull off)
    • Use correct size lug for cable
  4. Heat shrink over connection
    • Seals moisture out
    • Professional appearance
    • Apply heat evenly
  5. Label cables
    • “Solar Controller Positive”
    • “Solar Controller Negative”

Battery Fusing

Essential safety feature:

Fuse on positive cable:

  • Between controller and battery
  • Within 30cm of battery positive terminal
  • Rating: 1.25× maximum controller current

Example: 30A controller × 1.25 = 37.5A, use 40A fuse

Fuse types:

  • ANL fuse (best for high current)
  • MIDI fuse (common in automotive)
  • Blade fuse (okay for <30A)

I use ANL fuses (£3-5) with proper holders (£8-12). Rock solid.

Connecting to Battery

Connection sequence:

  1. Connect negative cable FIRST
    • Attach to battery negative terminal
    • Tighten securely
    • No spark (negative is safer to connect first)
  2. Connect positive cable LAST
    • Through fuse holder
    • To battery positive terminal
    • May spark slightly (normal)
    • Tighten securely

Why this sequence? If you drop a tool while connecting positive-first, it can short to ground. Connecting negative first makes this less likely to cause problems.

Controller Configuration

After battery connected:

  1. Controller should power up
    • Display lights (if it has one)
    • LEDs indicate status
  2. Configure battery type
    • Lithium, AGM, Gel, Flooded lead-acid
    • Incorrect setting damages batteries
    • Refer to battery manufacturer specs
  3. Set charging voltages (if controller allows)
    • Bulk/absorption voltage
    • Float voltage
    • Some controllers have presets (easier)
  4. Connect solar panels (final step)
    • Controller should detect panel voltage
    • Begin charging if battery isn’t full
    • Monitor current flow

System Testing

Don’t skip this. Testing catches problems while they’re still easy to fix.

Test 1: Voltage Verification

With multimeter:

  1. Measure battery voltage
    • Should be 12.4-14.6V (12V system)
    • Note exact voltage
  2. Measure solar panel voltage
    • At controller solar terminals
    • Should be 18-22V per panel (varies by series/parallel)
    • In full sun
  3. Verify controller display matches multimeter
    • Within 0.1-0.2V is acceptable
    • Large discrepancies indicate issues

Test 2: Current Flow Test

On sunny day:

  1. Check controller display for charging current
    • Should show amps flowing to battery
    • Should approach panel rating in full sun
    • Example: 2× 100W panels = ~10-11A in series
  2. Monitor for 30 minutes
    • Current should be stable
    • May vary with clouds
    • No sudden drops to zero (would indicate fault)
  3. Check battery voltage rise
    • Should increase gradually
    • Example: 12.4V → 12.8V over 1-2 hours
    • Indicates charging is working

Test 3: Load Test

Verify system powers loads:

  1. Connect typical load (lights, fridge, etc.)
  2. Monitor battery voltage
    • Should drop slightly under load (normal)
    • Should stabilize
    • Solar should reduce voltage drop (charging while under load)
  3. Verify controller manages charging correctly
    • Doesn’t shut off under load
    • Maintains appropriate charging

Test 4: Shade Test

Check for wiring issues:

  1. Shade one panel completely (cardboard over panel)
  2. Monitor system response
    • Current should drop (expected)
    • Should not drop to zero (would indicate series wiring issue)
    • Should continue charging from unshaded panel (parallel only)
  3. Remove shade, check recovery
    • Current should return to normal
    • Immediate response

Test 5: Overnight Monitor

Let system run overnight:

  1. Note battery voltage at sunset
  2. Check again at sunrise
    • Voltage should have dropped slightly (self-discharge and loads)
    • Controller should start charging when sun rises
    • Monitoring ensures controller sleeps/wakes correctly

Test 6: Leak Check

Critical after installation:

  1. Wait for heavy rain (or use hose)
  2. Check inside van around all mounting points
    • Feel for moisture
    • Look for water stains
    • Check immediately after rain
  3. Inspect panel mounting bolts
    • Should be dry
    • No water pooling
    • Sealant should be intact

If leaks found:

  • Don’t panic
  • Identify exact entry point
  • Remove bolt/bracket
  • Clean old sealant
  • Reapply fresh Sikaflex
  • Reinstall

I found a small leak after first installation (bathroom silicone failed). Fixed with proper Sikaflex. No issues since.

Troubleshooting

Common problems and solutions.

Problem: No Charging Current

Symptoms:

  • Controller shows 0A charging
  • Battery voltage not rising
  • Panels producing voltage but no current flow

Causes & Solutions:

  1. Battery already fully charged
    • Solution: This is normal. Wait until battery discharges slightly.
    • Check: Battery voltage >14.4V = full, won’t accept charge
  2. Panel not in sun
    • Solution: Wait for sunny conditions
    • Check: Panel voltage should be 18-22V per panel in sun
  3. Faulty connection
    • Solution: Check all connections are tight
    • Wiggle wires while monitoring (loose connection will cause current fluctuation)
  4. Blown fuse
    • Solution: Check solar fuse, replace if blown
    • Investigate what caused fuse to blow
  5. Controller fault
    • Solution: Check controller display for error codes
    • Consult manual for troubleshooting

Problem: Low Charging Current

Symptoms:

  • Charging, but much less than expected
  • Example: 200W system producing 3-4A instead of 10-11A

Causes & Solutions:

  1. Cloudy weather
    • Solution: This is normal. Expect 20-60% output on cloudy days
    • No fix needed
  2. Shading
    • Solution: Reposition van to avoid shade
    • Even partial shade dramatically reduces output
  3. Wrong wiring configuration
    • Solution: Verify series/parallel wiring matches controller setup
    • Check polarity
  4. Dirty panels
    • Solution: Clean panels with water and soft cloth
    • Dust/dirt reduces output 10-20%
  5. Hot panels
    • Solution: This is normal in summer
    • Panels lose ~10% efficiency when hot
    • No fix, just accept it
  6. Cable voltage drop
    • Solution: Measure voltage at panels vs controller
    • Should be <0.3V difference
    • If higher, cables too thin or too long

Problem: Controller Error Codes

Common errors:

“Battery overvoltage”

  • Cause: Charging voltage too high
  • Solution: Adjust controller settings for battery type
  • Check: Battery type setting correct?

“Battery undervoltage”

  • Cause: Battery deeply discharged
  • Solution: Charge battery from mains/alternator first
  • Controller may not charge from very low voltage

“PV overvoltage”

  • Cause: Solar panel voltage exceeds controller rating
  • Solution: Check series wiring (too many panels in series?)
  • Verify controller rated for panel voltage

“PV reverse polarity”

  • Cause: Solar panel wires backwards
  • Solution: Disconnect immediately, swap wires
  • Check for controller damage (may need replacement)

“Temperature”

  • Cause: Controller overheating
  • Solution: Improve ventilation
  • Reduce load or move controller to cooler location

Problem: Fluctuating Current

Symptoms:

  • Current reading jumps around
  • Not stable
  • Varies second-to-second

Causes & Solutions:

  1. Clouds passing
    • Solution: This is normal
    • Clouds vary panel output rapidly
    • No fix needed
  2. Loose connection
    • Solution: Check and tighten all connections
    • Wiggle test each connection while monitoring
  3. Faulty panel
    • Solution: Test each panel individually
    • Replace faulty panel
  4. Controller MPPT tracking
    • Solution: Some fluctuation normal as MPPT seeks maximum power
    • If excessive (>20% variation in stable sun), controller may be faulty

Problem: Battery Not Reaching 100%

Symptoms:

  • Battery charges to 90-95% then stops
  • Never fully charged

Causes & Solutions:

  1. Insufficient solar
    • Solution: Battery uses more power than solar generates
    • Reduce consumption or add more solar
  2. Short charging time
    • Solution: Battery needs 4-6 hours of good sun to fully charge
    • Park in sun longer
  3. Wrong absorption voltage
    • Solution: Check controller settings match battery requirements
    • Lithium typically needs 14.2-14.6V absorption
  4. Battery degraded
    • Solution: Old batteries lose capacity
    • Test with load tester
    • May need replacement

Problem: Roof Leak

Symptoms:

  • Water inside van after rain
  • Wet around mounting bolts
  • Staining on ceiling

Solutions:

  1. Identify exact leak point
    • Feel around all bolts during/after rain
    • May need to remove interior panels to access
  2. Remove bolt and bracket
    • Note orientation for reinstall
    • Let area dry completely
  3. Clean old sealant
    • Remove all traces
    • Clean with isopropyl alcohol
  4. Reapply Sikaflex 252
    • Generous amount
    • On bracket underside
    • On bolt threads
  5. Reinstall and let cure 48 hours
    • Don’t drive until fully cured
    • Monitor after next rain

Prevention: Use proper marine sealant (Sikaflex), not bathroom silicone.

Maintenance

Solar systems are low-maintenance, but not no-maintenance.

Monthly Checks

5 minutes, once a month:

  1. Clean panels if dusty/dirty
    • Water and soft cloth
    • Don’t use abrasive cleaners
    • Morning or evening (not hot panels)
  2. Check mounting bolts for tightness
    • Vibration can loosen bolts over time
    • Quick visual and tactile check
  3. Inspect cables for damage
    • Look for chafing, cuts, damage
    • Check UV damage on cable jacket
    • Resecure loose cables
  4. Verify charging is working
    • Check controller display
    • Confirm current flow on sunny day

Annual Checks

30 minutes, once per year:

  1. Deep clean panels
    • Remove accumulated grime
    • Check for physical damage (cracks, delamination)
  2. Inspect all sealant
    • Look for cracks, gaps, or degradation
    • Reapply if necessary
    • Check bolt areas especially
  3. Check connections
    • Tighten all electrical connections
    • Look for corrosion (green/white deposits)
    • Clean terminals if needed
  4. Test full system
    • Verify charging current matches expectations
    • Check battery charging to 100%
    • Confirm controller settings haven’t changed
  5. Inspect interior cable routing
    • Check for chafing where cables pass through holes
    • Verify cable ties are secure
    • Look for moisture ingress around cable entry

Long-Term Maintenance

Every 2-3 years:

  1. Reseal mounting points
    • Sealant degrades over time
    • Remove bolts, clean, reapply fresh sealant
    • Preventative maintenance
  2. Replace worn cables
    • UV degrades cable jackets
    • If cracking or brittleness visible, replace
  3. Update controller firmware (if applicable)
    • Victron and some other brands offer updates
    • Improves performance and fixes bugs

Panel Cleaning Tips

Do:

  • Clean with water and soft cloth
  • Clean in morning/evening (cool panels)
  • Use long brush for hard-to-reach panels
  • Dry after cleaning (prevents water spots)

Don’t:

  • Use abrasive cleaners (scratches glass)
  • Clean hot panels (can crack from thermal shock)
  • Use pressure washer (can damage seals)
  • Walk on panels (will crack cells)

Final Thoughts

My first solar installation took 11 hours, involved two trips to buy forgotten parts, and resulted in a small leak that took a week to notice. My most recent installation took 6 hours with zero issues.

The difference? I learned that solar installation isn’t difficult—it’s methodical. The people who struggle are the ones who skip planning, rush through sealant application, or forget to test before sealing everything permanently.

If you take away one thing from this guide: test everything before making it permanent. Connect panels before mounting. Wire controller before sealing cables. Check for leaks before calling the job done. Problems found early are easy fixes. Problems found after everything’s sealed are expensive nightmares.

The most common mistake isn’t technical—it’s rushing. Take your time. Do proper surface prep. Use correct sealant. Test thoroughly. Your future self will thank you when the installation works flawlessly for years.

And please, use proper marine sealant. The £15 you save using bathroom silicone will cost you hours of remedial work when it fails after 6-12 months. Sikaflex 252 is expensive because it actually works. I’ve learned this the expensive way so you don’t have to.

My 200W system has been flawless for 22 months. Zero leaks, zero failures, zero regrets. It took 7 hours to install including multiple test cycles and proper sealant curing time. That 7 hours has saved me hundreds of hours of hookup dependency and given me freedom to camp anywhere.

Now go install some solar panels on your van, and actually read the Sikaflex application instructions before squeezing the trigger.

Where to Buy (UK Sources)

Solar panels:

  • Amazon UK (wide selection)
  • Renogy UK (www.renogy.com/uk)
  • 12V Planet (www.12vplanet.co.uk)
  • Bimble Solar (www.bimblesolar.com)

Controllers:

  • Amazon UK (EPEver, Renogy)
  • 12V Planet (premium brands)
  • Victron dealers (victronenergy.co.uk)

Mounting hardware:

  • Renogy UK (complete kits)
  • Amazon UK (generic brackets)
  • Van conversion specialists

Sealant (critical):

  • Sikaflex 252: Marine chandleries, eBay, Amazon
  • Sikaflex 521UV: Same sources
  • Don’t buy from hardware shops (they stock bathroom silicone, not marine sealant)

Cables:

  • 12V Planet (quality solar cable)
  • Vehicle wiring specialists
  • Amazon UK (verify specifications)

Tools:

  • Screwfix (drills, tools)
  • Toolstation (similar to Screwfix)
  • Amazon UK (specialized tools)

Continue Reading
By