At a glance
A campervan solar system is one of the most practical upgrades a van conversion can have. Once installed, it silently charges the leisure battery whenever the van is parked in daylight, extending off-grid time and reducing dependence on campsites with hook-ups or on running the engine to charge. The UK climate is less sunny than southern Europe but generates usable solar power for around eight to nine months of the year – a well-sized system covering a UK summer from April to October without needing any supplementary charging in most cases. Understanding the components and how to size them before buying is the difference between a system that genuinely transforms your van life and one that underperforms and leaves you short of power on day two.
Most UK retailers sell campervan solar kits as a bundle that includes the panel or panels, a charge controller, and the cabling and connectors needed to wire the system together. The leisure battery and inverter are almost always sold separately, as these are the elements most dependent on individual power requirements and budget. A basic 100W kit from a reputable supplier costs around £150-£200 and is adequate for lighting, phone charging, a 12V compressor fridge and a laptop. Scaling up to 200W or 300W adds more capacity for appliances like a coffee machine or hair dryer via a 240V inverter, or simply extends the number of overcast days the system can cover before the battery needs external top-up.
The UK’s position at latitude 50-58 degrees north means solar generation is significantly lower than in southern Europe, but this does not prevent effective off-grid use. A 200W system in southern England generates around 800-1,200Wh per day in high summer (April-September), dropping to 200-400Wh per day in the depths of winter. This seasonal swing is why most van converters size their system for summer use and accept that winter travel may require supplementary charging from a B2B (battery to battery) charger connected to the alternator. In practice, most UK campervanning happens between April and October, making the summer generation figures the most relevant ones for sizing decisions.
What a Campervan Solar Kit Includes
A complete campervan solar kit should contain at minimum: the solar panel(s), a charge controller (either PWM or MPPT), MC4 connectors for joining panel cables, a cable from the controller to the battery, and mounting hardware for the roof. Many kits also include a battery monitor and a fused connection kit. What the kit does not include – and what you must budget for separately – is the leisure battery itself, the cabling inside the van from the battery to your 12V distribution board, and an inverter if you need 240V output.
When comparing kit listings, look carefully at what is actually in the box rather than the headline wattage figure. Some budget kits include only the panel and a basic charge controller, leaving you to source connectors, cable, fuses and mounting hardware separately – which can add £40-£80 to the total cost and trip up first-time buyers who assumed the kit was complete. The best-value kits from established van conversion suppliers include everything from cable entry gland (the waterproof fitting that passes the cable through the roof) to the correct fuse holder and appropriately rated cable for the panel output. Spending slightly more on a complete kit from a specialist retailer rather than a bare panel from a general electronics marketplace almost always delivers better value and fewer frustrating return trips to buy missing parts.
The choice between PWM (Pulse Width Modulation) and MPPT (Maximum Power Point Tracking) charge controllers matters more than many first-time buyers realise. PWM controllers are cheaper and adequate for small systems, but MPPT controllers extract 10-30% more energy from the same panel in real UK conditions – particularly valuable on overcast days when voltage is lower. For any system over 100W, an MPPT controller is the better long-term investment. Most quality kits above 150W now include MPPT as standard.
How to Size Your System
System sizing starts with an honest assessment of daily power consumption. The total watt-hours (Wh) needed per day determines both the panel capacity and the battery size required. Typical van appliances are listed below with approximate daily consumption figures – add up the ones that apply to your use case to arrive at your daily consumption figure, then work backwards to determine what panel and battery capacity you need.
The 1.5x rule for battery sizing. Whatever your calculated daily consumption in Wh, divide by 12 to get Ah, then multiply by 1.5 to avoid regularly discharging below 50% (which degrades lead-acid batteries rapidly). So 360Wh daily / 12 = 30Ah x 1.5 = 45Ah absolute minimum battery. In practice, round up to the next standard size and add a buffer for overcast days. Lithium batteries can be discharged to 80-90% without the same degradation penalty, so the calculation is more forgiving with LiFePO4.
What a Complete System Costs
The cost of a complete campervan solar installation depends heavily on whether you are installing a basic leisure system or a fully specified off-grid setup with lithium batteries. The figures below are for self-installation – professional installation adds around £200-£500 depending on complexity. All prices are approximate 2025 UK retail figures.
What to Look for When Buying a Kit
The most important specification to verify before buying any campervan solar kit is the type of charge controller included. MPPT controllers outperform PWM in real-world UK conditions by a margin that is significant enough to affect daily usable power. Any kit priced under £100 almost certainly includes a PWM controller – this is fine for a 100W system on a budget, but should not be the default choice for anything larger. The controller rating in amps must also match the panel wattage: a 10A controller handles up to 130W on a 12V system; upgrade to 20A or 30A for larger arrays.
Panel quality varies considerably at the budget end of the market. Look for monocrystalline cells rather than polycrystalline – mono panels are more efficient per square centimetre, which matters when roof space is limited. Check that the panel has a bypass diode fitted, which prevents partial shading from one section of the panel from killing output across the whole panel – a common issue on van roofs where a roof rack, vent or aerial creates a shadow stripe. IP65 waterproofing for the junction box is standard on any panel intended for outdoor use; avoid anything rated lower. Warranty terms are also worth checking: a five-year product warranty and 25-year output warranty (guaranteeing at least 80% of rated output) are normal for quality panels from established brands.
Flexible panels are tempting but require careful selection. Flexible solar panels can be bonded directly to curved van roofs without mounting brackets, saving weight and reducing wind noise. However, flexible panels run hotter than rigid glass-fronted panels and degrade more quickly if there is no airflow beneath them. If using flexible panels, ensure they are bonded with a gap or use them only on vans where the roof profile leaves some air movement. Rigid panels on low-profile mounts remain the more reliable long-term choice for most van builds.
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