Faster chargingFoldable solar panel
Portable panels that plug into most power stations. Match the voltage and connector to your station.
Enter your station and panels to see a panel size that fits.
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Solar charging time calculator
How long will your solar panels take to refill a power station? Enter the battery, the panels and your sun hours. Results update as you type.
- Counts real-world losses
- Free, no sign-up
- Runs in your browser
Solar charging time calculator
Your power station
Your solar panels
How long it takes
Charging time in days of sun and hours of full sun, with the power that reaches the battery.
How it works
Solar panels are rated in watts under lab conditions. A battery needs watt-hours to refill. Time is the energy needed divided by the power that actually reaches the battery.
- 1Energy to addbattery Wh × (target % − current %)
- 2Power reaching the batterypanel W × 0.8, capped at the station's maximum solar input. The 0.8 covers heat, sun angle, dust and wiring.
- 3Timeenergy ÷ power gives hours of full sun. Divided by your sun hours a day, that is days.
Sun hours are peak-sun hours, not daylight hours. Charging slows as the battery nears full, and anything plugged in at the same time uses some of the solar power, so allow extra time.
Worked example: a 1,024 Wh station from 20% with one 200 W panel
At 4 sun hours a day, a cautious US average:
Energy to add1,024 Wh × (100% − 20%) = 819 Wh
Power reaching the battery200 W × 0.8 = 160 W
Hours of full sun819 Wh ÷ 160 W = 5.1 hours
Days at 4 sun hours5.1 ÷ 4 = about 1.3 days
A second 200 W panel would halve that, as long as the station accepts 400 W of solar input.
Frequently asked questions
How long does a 200 W solar panel take to charge a 1,000 Wh power station?
About 6 hours of full sun from empty: 1,000 Wh ÷ (200 W × 0.8) = 6.25 hours. At 4 sun hours a day that is about a day and a half.
What are sun hours?
Peak sun hours are the hours of full-strength sun a place gets in a day, adding up weaker morning and evening light. 4 is a cautious average for much of the US. Winter in the north is often 2 to 3, and summer in the south can reach 6 or more.
Why does a 200 W panel give less than 200 W?
Panels are rated in lab conditions. Heat, sun angle, dust, wiring and the charge controller usually cut real output by about a fifth, so the calculator uses 80%.
Can I connect more panels than the station’s solar input?
Only within the station’s voltage and current limits, which are in the manual. Within those limits, extra panel watts get clipped in full sun but help on cloudy days and in the morning and evening. Too much voltage can damage the station.
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All in oneSolar generator kit
A power station bundled with matched panels, so the voltage and connectors already fit.
Enter your station and panels to see a kit size that fits.
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