Rooftop Solar Payback Calculator for Homeowners
Installing a rooftop solar system is a long-term investment that depends on your system size, local sunlight, electricity rates, incentives, and panel degradation. This calculator lets you enter realistic inputs—such as a 6 kW system, $2.80 per watt installation, and 5.5 average sun hours—in order to estimate annual generation, savings, and how quickly the installation pays for itself.
For example, many suburban homes in the U.S. install 5–7 kW systems. At $2.80 per watt, that equals roughly $16,800 before incentives. With net metering, each kilowatt-hour offsets utility bills, and state/local rebates can cut the upfront cost by 15–30%. Cumulative savings over 25 years, even accounting for annual panel degradation of 0.5%–1%, frequently surpass the sticker price by two- to three-fold.
Calculator Inputs
Typical residential systems fall between 4 and 8 kW. Average in the Sun Belt is between 5 and 6 hours.How the Outputs Relate to Your Investment
First-year energy production is based on system capacity times average daily sun hours, then multiplied by 365 and a 75% performance ratio to account for inverter losses and dust. Electricity savings multiply that kWh figure by your rate, so a 6 kW array producing 14,000 kWh a year at $0.16/kWh translates to $2,240 in avoided utility bills.
Simple payback is the number of years it takes cumulative savings to reach the net cost after incentives; we cap this at 30 years in the calculator to reflect realistic ownership horizons. Twenty-five-year savings include degradation, showing how panels gradually produce slightly less energy even though utility inflation still increases value.