Enter your average electricity bill and country. Solargrin fills in the rest with local sun-hour and pricing data — you can override anything.
Estimate only, based on national averages. Local shading, roof orientation and utility rules will change the real numbers — use this to shortlist, not to sign a contract.
Further reading: How Many Solar Panels Do You Actually Need? A Complete 2026 Guide
Solargrin sizes your system the same way an installer's back-of-envelope estimate does: it converts your electricity spend into annual usage, then figures out how large an array is needed to produce that much energy given your area's average sunlight.
"Efficiency" here is a derate factor that accounts for inverter conversion loss, wiring resistance, dust, and panel temperature — real-world arrays rarely hit their lab-rated output, so 80% is a conservative, realistic default.
Sun hours, electricity rates and typical install cost per watt vary enormously by market — a system that pays back in 4 years in Pakistan can take 12+ years in a low-rate US state. Switching the country dropdown updates all three defaults so the estimate stays realistic without you having to look anything up.
This estimate is based on what you use, not what your roof can physically hold — if you want the reverse view, the Roof Size to Solar Calculator tells you the maximum system your roof can fit.
Most homes need one panel for every 350–500 kWh of annual usage. Enter your monthly bill above for a number specific to your usage and location.
Only up to the point where production matches usage. Oversizing beyond your utility's net-metering export rate often adds cost without proportional savings — see the ROI calculator to check the marginal return.
It's accurate enough to know your rough budget and to sanity-check installer quotes, but a real design needs a site survey for shading, roof condition and orientation.