Calculator
Solar array watts to recharge your load
Size the solar array (watts) needed to replace your daily energy use, given your location's peak sun hours and typical system losses.
Related calculators
Looking for a definition or a quick answer? See the solar & battery glossary for terms used on this page, or the FAQ for common sizing questions. For the full explanation, read the peak sun hours guide.
Sources & standards
- NREL PVWatts Calculator — NREL's solar-production model; its default system-loss breakdown underlies the ~0.75 array loss factor used here.
- NREL PVWatts Version 5 Technical Reference — Documents the individual loss terms (soiling, wiring, temperature, availability) that make up the system derate.
- PVGIS — Photovoltaic Geographical Information System (EU Joint Research Centre) — Long-term solar-irradiation database used for the peak-sun-hour figures by location.
Estimates for planning only. Verify with a meter and follow NEC / local code; have a licensed installer confirm any system before purchase or wiring. See the methodology for formulas and sources.