Homeowner tool
A salesperson's "recommended" system is often sized to their commission, not your roof. Put in three numbers and get an independent ballpark: how big a system your usage calls for, and whether your roof can even fit it. Everything runs on your device. Nothing you type is sent anywhere.
ZIP, usage, roof. About 30 seconds.
Look for "kWh used" on your utility bill. Best is the average of your last 12 months; a typical month is fine for a ballpark.
Rough it out: length x width of the clear sections that face roughly south, east, or west. Skip north-facing faces, vents, and shaded spots.
Enter a valid ZIP, your monthly usage, and your usable roof area.
* This is an estimate only.
Real system size and production depend on things this tool can't see: shading from trees and neighboring roofs, your roof's actual usable area and pitch, which direction each face points, fire-code setbacks, your panel and inverter choice, and your utility's rules. Treat this as a sanity check to walk into quotes informed, not as a design. Get an on-site assessment from a licensed installer before you buy anything.
Next steps