Solar Output Calculator
A free, browser-based calculator. Runs entirely in your browser — no sign up, nothing stored.
100% FreeRuns in your browserBasic
Enter Values
Enter your values and press Calculate to see results.
How to use this calculator
- Enter the system size in watts and the peak sun hours for your area.
- Optionally set efficiency, then Calculate.
How it works
Daily energy = system size (W) × peak sun hours × efficiency, divided by 1000 for kWh. Efficiency (default 75%) covers inverter, wiring, temperature and dirt losses.
Worked example
400 W, 5 sun hours, 75%. 400 × 5 × 0.75 ÷ 1000 = 1.5 kWh a day.
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Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.