Solar Panel Efficiencyi How Is It Calculated?
Photovoltaic solar generation combines array capacity, tilt angle, geographic solar irradiance, and atmospheric cloud cover.
This tool utilizes standard US peak sun hour data. The American Southwest averages over 5.5 to 6.5 peak hours daily, while northern states average 3.5 to 4.5 peak sun hours.
Tilt angle significantly impacts yearly production. For most US latitudes (~30°N to ~45°N), a tilt angle matching local latitude (typically 30°–38°) maximizes annual kilowatt-hour output. Flat (0°) or vertical (90°) mounting can lose 20–30% of potential yield.
Cloud cover reduces solar irradiance: thick overcast conditions reduce solar generation by 60–80%. This calculator estimates daily and monthly kWh yields to project electricity bill savings.