Solar Panels for Campervans, Motorhomes and Caravans UK

A rooftop solar panel is one of the most common upgrades UK campervan and motorhome owners fit, and for good reason: it lets you run a 12V fridge, lighting, water pump and phone/laptop charging for days at a wild camping or non-hookup pitch without needing to plug in or run the engine. It's a genuinely different design problem from home solar, though — smaller loads, a 12V/24V DC system instead of mains AC, a strict weight budget, and none of the government incentives that apply to a house. Here's how to size a system properly for UK conditions.

How much solar do you actually need?

Sizing comes down to two decisions: panel wattage and battery capacity, matched to how you actually use the van.

• Weekend use, no fridge: a single 100W panel is usually adequate for lighting, phone and laptop charging alongside a modest leisure battery.
• Weekend-to-week use with a compressor fridge: 200W of panel paired with a 100Ah lithium (LiFePO4) leisure battery is the combination most UK retailers and van converters land on as the practical sweet spot — enough panel to keep a fridge running through a typical UK summer day, with the battery providing a buffer for overcast spells.
• Full-time van life or year-round use: 300–400W of panel with a 200Ah-plus lithium battery gives meaningfully more headroom through the shorter, duller days outside summer.

Panel output swings hard across the UK year. A single 100W panel produces roughly 300–500Wh on a clear summer day, but that can fall to well under 150Wh on a grey December day — the same seasonal gap that affects home solar, just at campervan scale. Don't size a system around a sunny July afternoon; size it around the dullest realistic day you'll actually camp in, or budget for supplementing with a mains hookup or the vehicle's alternator in winter.

Rigid vs flexible panels for a van roof

The same trade-off that applies to boats applies here. Rigid, framed monocrystalline panels are more efficient, dissipate heat better because the frame creates an air gap under the panel, and last longer — but they add height and weight, and need a rack or standoff mount. Flexible panels sit flush and add almost no wind resistance, which matters for fuel economy and roof-box compatibility, but they run hotter against the roof surface (reducing output) and typically have a shorter working life, often 10–15 years under continuous UV exposure versus 20-plus for a rigid panel. Whichever you choose, an IP65-or-better rated panel and junction box is the minimum for UK weather.

MPPT controllers and the 12V/24V system

An MPPT (Maximum Power Point Tracking) charge controller extracts meaningfully more usable energy than an older PWM controller, particularly in the UK's typically variable, part-cloudy conditions — the same reason MPPT dominates marine and off-grid installs generally. Victron Energy's SmartSolar range is the most common choice among UK van converters, offering Bluetooth monitoring via the VictronConnect app and models sized for everything from a single 100W panel up to multi-panel 400W-plus arrays on a 12V or 24V system. The controller should be fused on both the panel and battery sides, and mounted where it can dissipate heat — not buried in an enclosed cupboard.

Leisure batteries: lithium has mostly replaced AGM

Older campervan conversions commonly used sealed AGM leisure batteries, but they should only be discharged to around 50% of rated capacity to protect cycle life — a 100Ah AGM battery gives roughly 50Ah of genuinely usable capacity. LiFePO4 (lithium iron phosphate) batteries have largely taken over new builds because they offer 80–90% usable depth of discharge, weigh significantly less for the same usable capacity, and last for several times more charge cycles — an important factor given how much weight matters in a van build (see below). The trade-off is a higher upfront cost, though prices have fallen sharply as LiFePO4 has become the default choice across the leisure-vehicle market.

Payload: the limit that catches people out

Every motorhome and caravan has a Maximum Technically Permissible Laden Mass (MTPLM) — the maximum legal weight of the vehicle plus everything in and on it, set by the manufacturer and stamped on the chassis or VIN plate. Solar panels, mounting rails, an extra leisure battery and cabling all count against your payload alongside water, gas, luggage and passengers — and DVSA does check weights at leisure vehicle shows and roadside stops, with enforcement action for vehicles found overloaded. A single rigid panel and mounting kit typically adds several kilograms, and a lithium leisure battery bank can add considerably more — not usually enough on its own to overload a vehicle, but worth adding up alongside everything else you're carrying rather than assuming a small panel is negligible. Check your specific vehicle's payload margin before adding solar, water, and battery capacity together.

Does the 0% VAT relief on solar apply to a campervan?

No — and this is a common point of confusion. The 0% VAT rate on solar panels, batteries and other energy-saving materials (VAT Notice 708/6) is explicitly scoped to residential accommodation — a house, flat or similar dwelling. A motorhome, campervan or caravan is a vehicle, not residential accommodation in the sense HMRC's guidance uses, so a DIY or supply-and-fit campervan solar kit is standard-rated VAT, the same as any other vehicle accessory. If you're comparing quoted prices between a home solar installer and a van conversion company, that VAT difference is one reason the effective cost looks higher for the van kit even before accounting for the smaller scale. For the residential rate and what does qualify, see our guide to VAT on electricity and solar.

Similarly, van and boat solar sits outside the G98 grid-notification framework and the Smart Export Guarantee entirely, because it isn't connected to the electricity grid — there's no DNO to notify and no export income to earn. It's a genuinely self-contained system, closer in spirit to our off-grid solar guide than to a grid-tied home installation.

Getting it installed

Most campervan solar is DIY-fitted or done by a van conversion specialist rather than an MCS-certified domestic solar installer — MCS certification and its associated schemes (SEG, the Boiler Upgrade Scheme) apply to fixed residential and small-scale generation, not vehicle-mounted kits. That means quality control rests more on the individual fitter or your own competence with 12V DC wiring, fusing and cable sizing than on a national certification scheme. Undersized cable on a 12V run is a genuine fire risk — it's the same underlying issue the Boat Safety Scheme specifically checks for on boats — so if you're not confident with DC electrical work, a specialist van conversion company is worth the labour cost.