Solar Panel Installation
A comprehensive guide to choosing, sizing, and installing solar panels on your campervan — from panel types and charge controllers to wiring and testing.
Why Solar for Your Campervan?
Solar panels are the cornerstone of any off-grid campervan electrical system. They silently charge your leisure battery while you're parked up, giving you free electricity from the sun. Even in the UK's often-cloudy climate, modern solar panels produce useful amounts of power year-round. Combined with a properly sized battery and an efficient charge controller, solar gives you the freedom to camp without hookups for days or even weeks at a time.
Free Energy
No running costs once installed — sunlight is free
Off-Grid Freedom
Camp anywhere without needing hookups or campsites
Silent Operation
No noise or fumes — unlike generators
Solar Panel Types
Efficiency: 20 – 23% · Lifespan: 25+ years · Weight: 10 – 12 kg per 100W · £60 – £120 per 100W
Traditional rigid solar panels with an aluminium frame and tempered glass front. The most efficient and widely used type for campervan roofs.
Pros
- Highest efficiency per m²
- Very durable and long-lasting
- Well-proven technology
- Easy to mount with brackets
- Good performance in partial shade (with bypass diodes)
- Widely available and affordable
Cons
- Heavy compared to flexible panels
- Requires mounting brackets (adds height)
- Can't conform to curved roofs
- Aluminium frame can corrode if not maintained
- Adds wind resistance at speed
Efficiency: 18 – 21% · Lifespan: 5 – 10 years · Weight: 2 – 3 kg per 100W · £80 – £180 per 100W
Thin, lightweight panels that can bend to conform to curved van roofs. Glued directly to the roof surface for a low-profile installation.
Pros
- Very lightweight
- Low profile — almost flush with roof
- Can conform to curved surfaces
- No mounting brackets needed
- Minimal wind resistance
- Easy to install with adhesive
Cons
- Shorter lifespan than rigid panels
- Can overheat when glued flat (reduces output)
- More expensive per watt
- Harder to replace if they fail
- No air gap means less cooling
- Some delaminate over time
Efficiency: 13 – 16% · Lifespan: 10 – 15 years · Weight: 1.5 – 2.5 kg per 100W · £150 – £300 per 100W
Copper indium gallium selenide thin-film panels. Very flexible and lightweight, with better performance in low light than crystalline panels.
Pros
- Extremely lightweight and flexible
- Better low-light performance
- Very thin profile
- Good for partial shade conditions
- Can be walked on (some models)
Cons
- Lower efficiency — need more roof space
- Expensive per watt
- Less widely available in UK
- Fewer mounting options
- Technology still maturing
Charge Controllers: PWM vs MPPT
Efficiency: 75 – 85% · £15 – £50
Basic charge controller that switches the solar panel connection on and off rapidly to regulate charging voltage.
Best for: Small systems under 200W, budget builds
Pros
- Very affordable
- Simple and reliable
- Good for small systems
Cons
- Less efficient than MPPT
- Wastes energy as heat
- Panel voltage must match battery voltage
Efficiency: 95 – 99% · £80 – £300
Advanced charge controller that optimises the voltage and current from the solar panel to maximise power harvest. Converts excess voltage into additional current.
Best for: All systems, especially 200W+
Pros
- Much more efficient than PWM
- Harvests 15-30% more energy
- Works with higher voltage panels
- Better performance in partial shade
- Essential for larger systems
Cons
- More expensive
- Slightly more complex to set up
- Overkill for very small systems
System Sizing Guide
Choose a system size based on your power needs and budget. These figures assume UK summer conditions (3-4 peak sun hours per day). Winter output will be significantly lower.
| Level | System | Daily Yield (Summer) | Suitable For | Cost |
|---|---|---|---|---|
| Basic | 100W Panel + 50Ah Battery | 300 – 500 Wh (summer) | Phone charging, LED lights, small fan | £200 – £350 |
| Standard | 200W Panel + 100Ah LiFePO4 | 600 – 1,000 Wh (summer) | Fridge, lights, fans, phone/laptop charging | £500 – £900 |
| Off-Grid | 400W Panel + 200Ah LiFePO4 | 1,200 – 2,000 Wh (summer) | Full off-grid: fridge, lights, laptop, inverter, diesel heater | £1,200 – £2,500 |
| Full-Time | 600W+ Panel + 300Ah+ LiFePO4 | 1,800 – 3,000 Wh (summer) | Full-time living: all above + microwave, hair dryer, coffee machine | £2,500 – £5,000+ |
Installation — Step by Step
Plan Your System
Calculate your daily power consumption, choose your panel size, battery capacity, and charge controller type. Consider your roof space, weight limits, and budget.
- List every electrical device and its wattage × hours of daily use
- Add 30% to your calculated daily consumption for losses and cloudy days
- In the UK, expect 3-4 peak sun hours in summer, 1-2 in winter
- Always use MPPT charge controller for systems over 200W
Mount the Panels
For rigid panels, use Z-brackets or corner brackets to mount the panel to the roof with a 25-50mm air gap underneath for cooling. For flexible panels, clean the roof and use Sikaflex or VHB tape.
- Rigid panels: use stainless steel Z-brackets or ABS corner mounts
- Leave at least 25mm air gap under rigid panels for cooling
- Drill through the roof for cable entry — seal with Sikaflex
- Use a cable gland for a professional, waterproof cable entry
- Flexible panels: clean the roof with IPA, apply Sikaflex 252 in strips
Run the Cables
Route solar cables from the roof through a cable gland to the charge controller location inside the van. Use proper solar cable (4mm² or 6mm²) rated for outdoor/UV exposure.
- Use MC4 connectors for panel-side connections
- Run cables through conduit or trunking for protection
- Keep cable runs as short as possible to minimise voltage drop
- Use 4mm² cable for runs under 5m, 6mm² for longer runs
Install the Charge Controller
Mount the charge controller in a ventilated location near the battery. Connect the battery first, then the solar panels. Never connect panels to the controller without a battery connected.
- ALWAYS connect battery to controller FIRST, then solar panels
- Mount the controller vertically for best heat dissipation
- Keep the controller within 1.5m of the battery if possible
- Install an inline fuse between the controller and battery
Connect the Battery
Connect the charge controller output to your leisure battery. Use appropriately sized cable with an inline fuse. For lithium batteries, ensure your charge controller has a lithium charging profile.
- Use at least 6mm² cable between controller and battery
- Install a 30A fuse within 300mm of the battery positive terminal
- Set the correct battery type on the charge controller (AGM, Gel, or Lithium)
- Victron SmartSolar controllers have excellent Bluetooth monitoring
Test and Monitor
Test the system in full sunlight. Check that the charge controller is showing charging, and monitor the battery voltage. Install a battery monitor for ongoing visibility.
- A fully charged 12V lithium battery reads 13.4-14.6V when charging
- Check panel output matches expectations (actual output is typically 70-80% of rated)
- Install a Victron BMV-712 or similar battery monitor
- Monitor for a few days to ensure the system meets your needs
Solar in the UK — What to Expect
The UK isn't known for its sunshine, but modern solar panels still produce useful power even on cloudy days. Here's a realistic expectation of what a 200W solar system produces across the year:
| Season | Peak Sun Hours | 200W Panel Output | Notes |
|---|---|---|---|
| Summer (Jun–Aug) | 4 – 5 hours | 600 – 800 Wh/day | Enough for most off-grid needs |
| Spring/Autumn | 2.5 – 3.5 hours | 350 – 550 Wh/day | Supplement with B2B charger while driving |
| Winter (Dec–Feb) | 1 – 2 hours | 100 – 300 Wh/day | B2B charger essential; consider hookup |
Where to Buy
Victron Energy (via dealers)
Premium MPPT charge controllers, battery monitors, and inverters. The gold standard.
Visit Victron →Bimble Solar
UK-based solar panel specialist. Good range of rigid and flexible panels for campervans.
Visit Bimble Solar →Photonic Universe
Complete solar kits for campervans with panels, controllers, cables, and mounting hardware.
Visit Photonic Universe →Some links on this page are affiliate links. If you purchase through these links, CamperBuild may earn a small commission at no extra cost to you.