Here's what's shocking: A single square meter of solar panel can generate anywhere from 150 to 250 watts under ideal conditions. But "ideal" rarely exists in real life. In a perfect world, the average roof in the U. can generate around 21,840 kilowatt-hours (kWh) of solar electricity annually—that's more than most homes need. Realistically, your roof's solar generation potential will be less than that. Free calculator with multiple units, efficiency modes, and detailed visualizations. This calculator provides estimates only and should not be used as the sole basis for solar system purchases or financial. We have calculated how many of either 100-watt, 300-watt, or 400-watt solar panels you can put on roofs ranging from very little 300 sq ft roof to huge 5,000 sq ft roof, and summarized the results in a neat chart. This is a standard 10kW solar system, consisting of 25 400-watt solar panels. Formula: Panels = (Roof Area × Usable % × (1 − Spacing Loss %)) ÷ Panel Area → Total Capacity (kW) = Panels × Panel Wattage ÷ 1000.
[PDF Version]