Campervan solar in the UK: what 200 W really gives you, month by month
Solar panel adverts quote watts. Your battery cares about watt-hours per day, and in the UK that number swings by a factor of about ten between June and December.
The numbers: 200 W of flat roof panel, Wh per day
Calculated as 200 W × average peak sun hours × 0.75 system factor (heat, dirt, flat mounting, controller and cable losses). Sunshine data: European Commission JRC PVGIS 5.3, SARAH-3, horizontal surface, monthly averages for 2020–2023, retrieved 1 November 2026.
| Location | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| London | 123 | 224 | 393 | 666 | 772 | 828 | 767 | 646 | 488 | 278 | 153 | 90 |
| Cardiff | 116 | 218 | 406 | 682 | 846 | 860 | 783 | 656 | 480 | 268 | 148 | 83 |
| Manchester | 88 | 176 | 368 | 624 | 696 | 767 | 650 | 586 | 434 | 220 | 114 | 72 |
| Edinburgh | 78 | 176 | 360 | 591 | 684 | 750 | 704 | 573 | 393 | 198 | 104 | 51 |
| Inverness | 56 | 146 | 336 | 555 | 644 | 738 | 652 | 546 | 369 | 176 | 81 | 39 |
These are averages. A grey week in July can be far lower, and parking under trees can halve them.
What that means for a typical van
A weekend van using about 600 Wh a day (fridge, lights, phones, fan) would need roughly this much flat solar to cover its use from solar alone:
| Apr | Jun | Sep | Oct | Dec | |
|---|---|---|---|---|---|
| London | 180 W | 145 W | 246 W | 432 W | 1,333 W |
| Edinburgh | 203 W | 160 W | 305 W | 606 W | 2,353 W |
So: - April to September: 200–300 W covers most weekend vans in most of the UK. - October to February: no realistic van roof covers a fridge from solar alone. You need a DC-DC charger (30 A × 1 hour of driving ≈ 360 Wh), hook-up, or lower use.
Five ways to get more from van solar
- Park for the sun. Shade costs more than any controller choice.
- Use an MPPT controller sized for the array (panel W ÷ about 14 V).
- Keep panels clean. Bird droppings on one cell can cut a whole panel's output.
- Tilting helps in winter, but flat panels are simpler and safer while driving.
- Combine sources. Solar for summer, DC-DC for winter, hook-up when needed.
Going to France?
The same 100 W gives roughly 58 Wh a day in Paris in December, 76 Wh in Lyon and 124 Wh in Marseille, against 45 Wh in London (same PVGIS method). In June it's 452, 481, 555 and 414 Wh respectively.
▶ Check your own van month by month with the free calculator: pick from 10 UK and French locations.
Estimates from public PVGIS data and a 0.75 system factor; real output varies. Not professional advice.