Use watt-hours for the day
A 100W label describes rated power under specified conditions. Daily energy depends on available sun and losses.
100W solar panel calculator
What can a 100W solar panel run?
Compare the usable energy a panel may collect in one good-sun day with the watt-hours your device needs. This answers the energy question; battery capacity, output watts, startup demand, and electrical compatibility remain separate checks.
Daily load coverage94.5%
The example is slightly short of its four-hour target after the entered losses and reserve.
Quick reference
100W panel energy at different sun hours
This table uses a 70% collection factor before any battery-output loss or reserve. It is scenario math, not a guaranteed panel yield.
| Peak sun hours | Nameplate energy | At 70% collection |
|---|---|---|
| 3 hours | 300Wh | 210Wh |
| 4 hours | 400Wh | 280Wh |
| 5 hours | 500Wh | 350Wh |
| 6 hours | 600Wh | 420Wh |
Interpret the number
Panel watts and device watts are not the same promise
The battery system runs the load
For a stored-energy setup, the battery and inverter must supply the device's running and startup watts even when the panel is producing less.
Watts alone cannot match hardware
Use the solar panel compatibility checker for the first voltage, current, and input-limit screen.
Method references: U.S. Department of Energy on rated PV conditions and performance factors and PVWatts v8 model assumptions. Sources checked July 16, 2026.
Next checks
Match the panel to the rest of the system
Solar recharge time calculator
Estimate how long the panel may take to replace energy in a specific battery.
Calculate recharge time100W vs 200W solar panels
Compare daily collection, charging limits, and the portability tradeoff.
Read the comparisonWill a 100W panel recharge it?
Work backward from battery capacity and the station's input ceiling.
Read the recharge guideFAQ
Common 100W panel questions
How many watt-hours per day?
At 4.5 peak sun hours and a 70% collection factor, the estimate is 315Wh before battery-output loss and reserve. Change both inputs for your conditions.
Can it run a refrigerator?
It may contribute energy, but the appliance's measured daily kWh, compressor startup, battery size, inverter output, and weather decide whether the full system works.