Solar Panel Payback & ROI Calculator
Find out how long it takes to break even on a solar installation, estimate your lifetime utility savings, and calculate the true return on investment after the Federal Tax Credit.
About this calculator
This calculator estimates the financial return of a residential solar installation. It derives your household's annual electricity consumption from your average monthly bill and local rate, sizes the solar array needed to cover that usage, then projects year-by-year cumulative savings over a 25-year system lifetime — accounting for panel degradation (0.5%/year) and annual electricity rate increases. The Federal Investment Tax Credit (ITC) is subtracted from the gross system cost upfront to give a realistic net cost basis. The break-even point is the year when cumulative savings exceed the net system cost, and the ROI is the net lifetime gain divided by that net cost.
Field explanations
- Avg. monthly electricity bill
- Your average monthly utility bill in dollars. Used with the utility rate to estimate your household's kWh consumption. Check your last 12 months of bills and use the average — summer and winter usage can vary widely.
- Utility rate (per kWh)
- Your electricity provider's rate in dollars per kilowatt-hour. The US average is around $0.13–$0.16/kWh, but rates range from $0.09 (Louisiana) to $0.30+ (Hawaii, California). Find your exact rate on your utility bill or your provider's website. Use the blended rate (total bill ÷ total kWh), not the tiered marginal rate.
- Gross system cost (before credits)
- The total quoted price for equipment and installation before any tax credits or rebates. As of 2024, a typical residential system (6–10 kW) runs $15,000–$35,000 before incentives. Get at least three installer quotes — costs vary significantly by region.
- Federal ITC (Investment Tax Credit)
- The federal tax credit percentage applied to the gross system cost. The ITC is 30% through 2032 under the Inflation Reduction Act, stepping down to 26% in 2033 and 22% in 2034. This is a dollar-for-dollar reduction in your federal income tax liability, not a rebate — you must have sufficient tax liability to use it.
- Average daily peak sun hours
- The number of hours per day when sunlight intensity averages 1,000 W/m² (full sun equivalent) at your location. This is not the number of daylight hours — a cloudy location with 10 daylight hours may have only 3.5 peak sun hours. Regional presets: Pacific Northwest ~3.5 hrs, Midwest ~4.0 hrs, Southeast ~4.5 hrs, Southwest desert ~5.5–6.5 hrs. Use the NREL PVWatts tool for a precise value for your address.
- Annual electricity rate increase
- The expected annual percentage increase in your utility rate. Historically, US electricity prices have risen about 2–3% per year on average. A higher escalation rate makes solar look more attractive over time since each year of solar savings is worth more.