Solar charging time calculator
How long will a solar panel take to charge your power station or battery? Includes real-world panel output, solar input limits and peak sun hours.
Results
| Charging time in full sun | 5 h 28 min |
|---|---|
| Days of sun needed | 1.09 days |
| Effective charging power | 150 W |
| Energy to add | 819 Wh |
- This takes more than one day of sun. Add panels, or top up from the wall or a car before heading out.
- Peak sun hours already account for weaker morning and evening light, so charging time is counted in full-sun-equivalent hours.
About this calculator
A "200 W" solar panel almost never charges at 200 W. Portable panels lying on the ground in summer heat typically deliver 60-75% of their rating at midday, and much less in the morning, evening or under haze. Your power station or charge controller also has a maximum solar input. Panels beyond that limit add nothing at peak, though they still help in weak light.
This calculator combines realistic panel output, the input limit and peak sun hours to estimate how many hours, and how many days, it takes to refill your battery from solar. It's useful for planning a camping trip, or for working out whether one panel can keep a fridge or CPAP going through a multi-day outage.
How to use it
- Enter total panel watts. Panels wired in series or parallel simply add up.
- Set the real-world output: about 70% for folding panels, about 80% for rigid panels aimed at the sun.
- Enter the station's or controller's maximum solar input from its spec sheet.
- Enter the battery size, current and target charge, and your location's peak sun hours.
The formula
Energy needed = capacity × (target − current) %.
Effective power = min(panel W × real-world %, input limit).
Hours = energy needed ÷ effective power. Days = hours ÷ peak sun hours.
Worked example (default values)
Inputs
| Solar panel watts (total) | 200 W |
|---|---|
| Real-world panel output | 75 % of rating |
| Max solar input of the station or controller (0 = no limit) | 500 W |
| Battery capacity | 1024 Wh |
| Current charge | 20 % |
| Target charge | 100 % |
| Peak sun hours per day | 5 h |
Results
| Charging time in full sun | 5 h 28 min |
|---|---|
| Days of sun needed | 1.09 days |
| Effective charging power | 150 W |
| Energy to add | 819 Wh |
Tips and common mistakes
Aim the panel. Repositioning a portable panel toward the sun two or three times a day can add 20-30% to daily harvest compared with leaving it flat. Keep panels cool and clean: output falls roughly 0.3-0.4% for every °C the cells heat above 25 °C, and on a hot day cells can easily run 25-35 °C hotter than the air.
Check voltage limits too. Power stations list an input voltage window, e.g. 12-60 V. Wiring panels in series can exceed it. Use the solar string voltage calculator before connecting more than one panel.
Frequently asked questions
How long does a 200W solar panel take to charge a 1000Wh power station?
At about 150 W real output, charging from 20% to 100% (about 820 Wh) takes roughly 5.5 hours of full sun, so about one sunny day.
Can I charge a power station with solar on a cloudy day?
Yes, but output may fall to 10-30% of normal. Expect charging to take several times longer.
Does a bigger panel charge faster?
Yes, roughly in proportion, up to the station's solar input limit.
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Estimates for planning only, based on the assumptions shown. Real-world performance varies with equipment, temperature and installation. Updated October 19, 2026. See our methodology.