We built the tool we wished existed when we were sizing our own solar systems — transparent, accurate, and completely free.
Millions of homeowners and small businesses worldwide are switching to solar energy — but most sizing tools are either locked behind sales funnels or riddled with inaccuracies.
SolarCalculator4U was created to give anyone — from a homeowner in Lahore to a contractor in Lagos — a genuinely useful, engineering-grade solar sizing calculator that runs entirely in the browser, with no ads, no paywalls, and no data collection.
Every formula in our calculator is grounded in accepted solar engineering standards — including NREL irradiance data and IEC battery chemistry specifications.
Whether you're in Pakistan, Nigeria, India, or the Philippines — anywhere with sunshine and power challenges — this tool works for your situation.
All calculations happen entirely in your browser. We never collect or store your appliance data. Zero sign-up required.
SolarCalculator4U will remain free forever. We believe the information needed to make smart energy decisions should be accessible to all.
Want to understand exactly how the calculations work?
Read Our Methodology →