Solar Payback Calculator: Payback Years and Lifetime Savings

Find out how long rooftop solar takes to pay for itself and what it could save over its life, using your own quote, electricity rate, local production and export credit. The calculator accounts for panel aging and rising electricity prices.

How to use this tool

1. Enter the system size and the installed price per watt from your quote.
2. Enter only incentives you have confirmed for your address and installation date.
3. Enter annual production per kilowatt from your installer’s estimate or NREL’s PVWatts.
4. Enter your electricity rate, how your utility credits exported power, and an expected yearly price increase.

Worked example

A 7 kW system at $3.00 per watt costs $21,000 before incentives. At 1,300 kWh per kW it produces 9,100 kWh in year one, worth about $1,547 at 17 cents per kWh with full credit for exports. With prices rising 2.5 percent a year and panels losing 0.5 percent a year, cumulative savings pass the cost in about 13 years.

Understanding your results

Payback is the first year your cumulative savings exceed the net cost. The biggest levers are price per watt, your electricity rate and the export credit. If your utility credits exports at well below retail, payback lengthens unless you use more solar at home or add storage. The estimate excludes financing, inverter replacement and roof work.

Common mistakes to avoid

• Counting incentives you have not confirmed.
• Using a generic production number instead of a site-specific estimate.
• Assuming full retail credit for exports where your utility uses net billing.
• Comparing quotes by total price instead of price per watt.

Next steps

Size the system with the Solar Panel Calculator and read Home Solar for net metering and incentives.

Frequently asked questions

What is a good solar payback period?

Payback depends heavily on local rates and policies. Many homeowners consider a payback well inside the panels’ warranty period worthwhile, but compare it with other uses of the money and confirm all assumptions.

Does solar raise my home's value?

Some studies have found owned solar systems can add value, but results vary by market. Leased systems can complicate a sale. Ask a local real estate professional.

How long do solar panels last?

Panels commonly carry 25 year power warranties and degrade slowly. Inverters usually need replacing sooner, which this calculator does not include.

This tool is for planning and education only. It does not store your entries. Work on home wiring must be done by a licensed electrician. Read our disclaimer.