Solar Panel Calculator

A solar panel number calculator estimates how many panels are needed based on annual electricity usage, local peak sun hours, and individual panel wattage. Use this calculator for accurate, instant results.

The calculator uses the standard published formula for solar panel number. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

This calculator works with inches, percentages, kilowatts, watts. You can enter values in the units shown — the calculator handles all conversions internally.

The core formula is: Annual generation per panel (kWh) = Wattage × Sun hours/day × 365 / 1,000. Each step in the calculation is shown so you can verify the result manually.