Solar Panel System GuideSolar tool
Solar Offset Calculator
Estimate what percentage of your annual home electricity use a solar system offsets from its yearly production.
Estimate only.Confirm with a pro and get a real quote. A professional solar site assessment and a written installer quote are authoritative for final system size, production, and cost.
Screening result
Fine Print and Sources
Estimate only. These tools use only the values you enter and simple planning math. Confirm with a pro and get a real quote. A professional solar site assessment and a written installer quote are authoritative for system sizing, production, and final purchase decisions.
Method: offset percentage equals annual production divided by annual home use, times 100. When production is left blank, it is estimated as system kW times 365 times peak sun hours times the derate factor. Real offset varies with production and consumption over the year.
- EnergySage solar sizing guide: explains how annual electricity use, peak sun hours, and panel wattage drive system size and panel count.
- NREL PVWatts calculator: a detailed production model that accounts for location, orientation, shading, and system losses.