The short answer
A panel produces about 75% of its rating × your peak sun hours in Wh per day. Two 200 W panels on an average Gulf Coast day add roughly 1,560 Wh — most of a day's refrigerator-and-router needs, but not a 3,000 Wh battery's refill.
The formula
Wattstanding calculationEnergy per day (Wh) = panel watts × 0.75 × peak sun hours. Days to refill = capacity ÷ energy per day.
| Panels | Gulf Coast (5.2 h) | Northeast (4.2 h) | Pacific Northwest (3.6 h) |
|---|---|---|---|
| 100 W | 390 Wh/day | 315 Wh/day | 270 Wh/day |
| 200 W | 780 Wh/day | 630 Wh/day | 540 Wh/day |
| 400 W | 1,560 Wh/day | 1,260 Wh/day | 1,080 Wh/day |
| 800 W | 3,120 Wh/day | 2,520 Wh/day | 2,160 Wh/day |
Practical notePeak sun hours are approximate annual averages; winter, cloud and shade can cut output by half or more. Hurricanes bring clouds — plan solar as a supplement, not the only source.
What limits charging
- The station's solar input: a maximum wattage, voltage and current. Panels beyond it are wasted; a panel above its voltage limit can damage it.
- Voltage (Voc) of panels in series; connect panels within the station's range as the maker specifies.
- Connector: MC4, 8 mm and proprietary plugs differ; adapters may be needed.
- Sun and angle: open sun, tilted toward it; partial shade can sharply cut output.
Use the solar recharge calculator and compare panels.
Other ways to recharge
Wall charging is the fastest when power is available, and many stations accept a generator's output through an AC input. Car charging is usually slow. A hybrid plan — solar by day, a short generator run when needed — is common in long outages.
Figures marked as Wattstanding calculations show their working; product figures come from the sources on each product page. How we work