Solar Payback Calculator

How to use this calculator

Enter Installed cost ($), Applicable incentives ($), Net annual savings ($). The result updates in your browser as you edit an input. The prefilled values are examples only.

How the estimate works

Divide installed cost after applicable incentives by net annual savings. Financing and future rate changes are excluded.

What can change the answer?

Simple payback ignores financing, maintenance, future electricity prices, roof work, and discounting. Incentive eligibility must be verified for your project.

Before relying on the result

Check that the figures use the same units and period. Compare the result against a current label, quote, contract, employer policy, or official dataset when appropriate. This estimate does not include factors you have not entered.

Further reference

For source data or a more detailed method, see National Laboratory of the Rockies: PVWatts production model. The calculator does not automatically import data from this source.

Worked example with the default inputs

An installed cost of $25,000, zero entered incentives and $1,800 net annual savings give simple payback of 13.89 years. This ratio excludes financing and changing future savings.

Interpret the result in a planning record

The simple payback calculator divides installed cost after entered incentives by net annual savings. Only include incentives that apply to your project and that you have independently checked. The calculation leaves out financing, future tariff changes, maintenance and the time value of money. It is one comparison measure rather than a complete investment analysis.

Save the input values, units and result together. Change one uncertain input at a time so you can see which assumption moves the answer. A displayed decimal is arithmetic precision, rather than evidence that the measurements or rates are equally precise.

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Read the How to Read a Solar Quote Without Mixing Up the Numbers guide →