Solar Panel Payback Calculator
A free, practical calculator. Your inputs stay in this browser.
How it works
Enter your monthly electricity use and price, system size, and installed cost per watt. Production is estimated at 1,400 kWh per kW per year (a U.S. average), the 30% federal tax credit is applied to the system cost, and the calculator returns the payback period and 25-year net savings.
Example
A 7 kW system at $2.90/W for a home using 900 kWh/month at $0.18/kWh pays back in about 8.1 years and saves about $29,890 over 25 years.
FAQ
How does the 30% federal tax credit work?
It reduces the net system cost used in the payback math. Whether you can claim the full credit depends on your tax situation — talk to a tax professional.
Where does 1,400 kWh per kW per year come from?
It is a U.S. average for rooftop solar production. Sunny states produce more; cloudy climates, shading, or poor roof orientation produce less.
What is not included?
Panel degradation over time, financing interest, maintenance or inverter replacement, state and local incentives, and future net-metering policy changes.