How many solar panels do you need to charge a power station?
Short answer
Plan on about 300 to 400 W of solar panels to recharge a 1,000 Wh power station in one day. Each 100 W of panels delivers roughly 225 to 450 Wh a day, depending on how much sun you get. The power station's maximum solar input also caps how fast it can charge, however many panels you connect.
Solar charging calculator
How the calculation works
Solar output depends on peak sun hours: the number of hours per day that equal full, direct midday sun. Most of the US gets roughly 3 to 6 peak sun hours depending on region and season.
Panels rarely deliver their full rating. Heat, angle, haze and charging losses typically cut output to around 75 percent, so we multiply by 0.75. Energy per day equals panel watts, times peak sun hours, times 0.75.
What 100 W of panels produces per day
| Conditions | Peak sun hours | Energy from 100 W of panels |
|---|---|---|
| Cloudy, or northern states in winter | 3 | 225 Wh |
| Typical US average | 4 | 300 Wh |
| Sunny spring or summer day | 5 | 375 Wh |
| Desert Southwest in summer | 6 | 450 Wh |
For the sun hours at your exact address, the free PVWatts calculator from the National Renewable Energy Laboratory gives month-by-month figures.
Panel watts to recharge 80% in one day
Recharging from 20% to 100% is the common case during an outage, since you rarely run a battery completely flat.
| Power station | At 4 sun hours | At 5 sun hours |
|---|---|---|
| 256 Wh | 100 W | 100 W |
| 512 Wh | 150 W | 150 W |
| 1,024 Wh | 300 W | 250 W |
| 2,048 Wh | 550 W | 450 W |
| 3,600 Wh | 1,000 W | 800 W |
The input limit catches people out
Every power station has a maximum solar input in watts. Connecting more panels than that does not charge any faster during the middle of the day, although a little extra can help in the morning, evening and on cloudy days. Check the limit before buying panels.
Tips for faster solar charging
- Point panels south (in the US) and tilt them toward the sun. Adjust the angle a couple of times a day if you can.
- Keep panels cool and clean. Output drops as panels heat up, and dust or shade on even part of a panel costs a lot.
- Charge while you use as little as possible during the day, and save the battery for the evening.
Frequently asked questions
How many solar panels do I need to charge a 1,000 Wh power station?
About 300 to 400 W of panels will recharge a 1,000 Wh power station from nearly empty in one typical day of 4 to 5 peak sun hours. With a single 100 W panel it takes three or more days.
How long does a 100 W solar panel take to charge a power station?
A 100 W panel produces roughly 225 to 450 Wh on a clear day, depending on your location and season. That recharges about a quarter to a half of a 1,000 Wh power station per day.
Why does my 200 W panel only deliver about 150 W?
Rated watts are measured in ideal lab conditions. Heat, panel angle, haze, dust and charge controller losses reduce real output, which is typically 70 to 80 percent of the rating at midday.
Can I connect any solar panel to my power station?
Only if the panel's open-circuit voltage and current fall within the power station's solar input range, and you have the right connector or adapter. Check both specs before buying, especially when wiring panels in series.
Sources and method
Runtime figures assume 85% of battery capacity reaches AC appliances and typical US appliance ratings. See exactly how we calculate. Found a mistake? Tell us and we will fix it.