Estimates how much energy a solar panel produces per day from its rated wattage, local peak sun hours, and a system efficiency factor covering real-world losses.
How it works
The panel’s wattage is multiplied by peak sun hours and the system efficiency percentage, then divided by 1,000 to give kilowatt-hours.
What this does not include
This does not include a payback period or cost analysis — for that, use this site’s solar panel payback calculator instead, which starts from a given annual savings figure.
How to use this calculator
- Enter the panel wattage, average peak sun hours for your location, and a system efficiency estimate.
Frequently asked questions
What are “peak sun hours”?
A standardized measure of how many hours per day the sun delivers energy at full intensity (1000 W/m²) — not the same as total daylight hours.
Why isn’t system efficiency 100%?
Real installations lose some energy to inverter conversion, wiring resistance, heat, dust, and panel aging — a well-installed system typically runs 75-85% efficient.
Is this an exact prediction of my system’s output?
No — it’s an estimate. Actual output varies with weather, shading, panel angle, and seasonal changes in sun hours.
