Most campervans run well on 200 to 400W of solar. A weekender with a compressor fridge, lights, and phone charging needs about 200W; full-time living with a laptop and Starlink wants 400 to 600W. Here's how to size yours instead of guessing.
| Equipment | Typical use per day |
|---|---|
| 12V compressor fridge | 500 to 600 Wh |
| Starlink (8 hours) | 300 to 400 Wh |
| Laptop (charged daily) | 150 Wh |
| 12V fan (overnight) | 100 Wh |
| Diesel heater fan (winter) | 50 Wh |
| LED lights (evening) | 30 to 50 Wh |
| Phone and tablet charging | 30 Wh |
| Water pump | 10 Wh |
A typical build lands at 700 to 900 Wh per day: fridge, lights, charging, and a laptop. Starlink pushes it past 1,100.
Divide daily watt-hours by your location's peak sun hours, then divide by 0.7 to cover wiring, controller, and battery losses. Peak sun hours run about 5 in the southern US in summer, 3 to 4 in the shoulder seasons, and as low as 2 in a UK or northern-US winter.
Example: 800 Wh ÷ 4 sun hours ÷ 0.7 = 285W, so a 300W setup. The same load in a UK winter: 800 ÷ 2 ÷ 0.7 = 570W. Size for the worst month you'll actually camp in, and remember panels lying flat on a roof give up midday output in winter: our RV tilting guide shows how much.
Carry about two days of consumption in usable battery, so cloudy days don't end the trip. At 800 Wh per day that's roughly 1,600 Wh: around 150Ah of lithium at 12V.