Solar Charge Time Calculator

Estimate recharge time from battery watt-hours, panel watts, station input limit, sun hours, and realistic solar derating.

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Optional station preset

Full refill at current solar input

3h 13mFull refill at current solar input: 3h 13m

Based on 300 W effective solar input. Refill needs 3h 13m of usable sun, about 0.7d at 4.5 peak sun hours/day.

Refill target963 Wh
Daily solar1,350 Wh
Runtime offset16h 53m
Load coverageoffsets load
Conservative4h 1m
Estimated3h 13m
Optimistic2h 44m

Conservative assumes harder conditions; optimistic assumes favorable conditions.

Solar output changes with shade, heat, clouds, panel angle, wiring, charge-controller behavior, and whether the station is already near full. Treat this as a planning estimate.

What To Check Next

Use With Runtime

Add the daily solar Wh to your load plan only when panels are deployed during usable sun hours.

Measurement Tip

Compare the station display's solar input against this estimate and adjust the derate until it matches your real setup.

Verify your watts

  • Check the device label for running watts or input amps and volts.
  • Use a plug-in watt meter for AC loads when the result matters.
  • For cycling loads, measure long enough to capture on/off behavior.

Check output path

  • AC inverter loads usually lose more energy than direct DC loads.
  • Keep reserve for cold weather, battery age, and load changes.
  • Do not treat label capacity as fully usable watt-hours.

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