Calculate the solar system size (kW) and number of panels your home needs from your monthly kWh usage and local sun hours.
Estimate only. Prices, sun hours and rates vary by location and installer.
We convert monthly kWh to a daily need, then divide by your local peak sun hours and a system efficiency factor to size the system, and estimate panel count at 400W each.
Plan your solar project with our free tools.
The right system covers your actual electricity use given how much sun your location gets. We take your monthly kWh, break it into a daily target, and divide by local peak sun hours and a real-world efficiency factor. Cloudier regions need more panels for the same usage — which is why a Phoenix and a Seattle home with identical bills get different system sizes.
Enough kW to cover your daily kWh given local sun hours — often 6–10 kW for a home.
The equivalent hours of full-strength sun per day in your area.
Real systems lose ~20% to heat, wiring and inverter losses.
No — an installer will refine it with your roof and shading.