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Solar Payback Calculator

Solar payback calculator

Find out how long solar panels would take to pay for themselves on your home, and what they could save over 25 years. Pick your country, then change any starting figure to match your bills and your quote.

Your home

All amounts in US dollars.

Your home

Sets how much electricity each kW of panels makes in a year at your location.

kWh per month

Check your utility bill: most show monthly kWh. Average your last 12 months if you can.

cents per kWh

Starts at the US residential average. Your bill shows your own rate.

Solar system
kW

Leave blank to size the panels to cover your yearly use, or enter the size on your quote.

Installed price
$per W

Enter the price from your installer quote to see cost, payback and return. Your quote divided by the system size in watts (for example, a 6 kW system is 6,000 W).

Assumptions you can change
% per year

Starts at 0.5%, the median of nearly 2,000 reported rates in an NREL review.

% per year

A scenario, not a forecast. Try 0% and 5% to see how much it matters.

%

Share of the panels’ output your home uses as it is made. 100% assumes all of it offsets power you would otherwise buy, up to your annual use.

A battery only adds savings when you use less than 100% of your solar power directly. Lower “Used directly at home” under assumptions to model that.

Results

Payback period

Add your installer’s quoted price to see payback

First-year savings
$1,962
Savings over 25 years
$66,899
System size
7.1 kW
Sized to cover your yearly use
First-year generation
10,788 kWh
Cumulative savings over 25 yearsAdd your quoted price to compare against the cost.
Year-by-year table
Generation and savings for each of the 25 years
YearGeneration (kWh)Price per kWhSaved that yearSaved so far
110,788$0.182$1,962$1,962
210,734$0.187$2,011$3,973
310,680$0.193$2,061$6,035
410,627$0.199$2,112$8,147
510,574$0.205$2,165$10,312
610,521$0.211$2,219$12,530
710,468$0.217$2,274$14,804
810,416$0.224$2,330$17,134
910,364$0.230$2,388$19,522
1010,312$0.237$2,447$21,970
1110,261$0.244$2,508$24,478
1210,209$0.252$2,571$27,049
1310,158$0.259$2,634$29,683
1410,107$0.267$2,700$32,383
1510,057$0.275$2,767$35,150
1610,007$0.283$2,836$37,986
179,957$0.292$2,906$40,892
189,907$0.301$2,979$43,871
199,857$0.310$3,053$46,923
209,808$0.319$3,128$50,052
219,759$0.329$3,206$53,258
229,710$0.338$3,286$56,544
239,662$0.349$3,367$59,911
249,613$0.359$3,451$63,362
259,565$0.370$3,537$66,899

Savings count only electricity your home no longer buys. Power sent to the grid is valued at zero. Grid emissions data has not been verified yet, so no carbon figure is shown. See the methodology for every formula and source.

Country pages

Each country page has the same calculator plus answers to local questions.

Guides for US homeowners

  • How solar payback is calculated

    The payback formula step by step: system size, yearly output, the value of each kWh, rising prices and panel wear, with a worked example and the inputs that move the answer most.

  • Solar panel degradation explained

    Why solar panels make a little less power each year, what the research says about typical rates, how to read a performance warranty and how much wear changes payback.

  • Do home solar batteries pay off?

    When a battery adds real savings to a solar system and when it only adds cost, how to work out the most a battery is worth to you, and what the numbers leave out.

Frequently asked questions

How is the payback period worked out?
Each year, the calculator multiplies the electricity your panels replace by the price you would have paid for it, and adds that to a running total. The payback period is the point where the running total equals the installed price. Within the year that happens, it assumes savings arrive evenly, so a result of 11.4 years means partway through year 12.
Where do the starting figures come from?
From published government and laboratory sources: US electricity prices and household use from the US Energy Information Administration, US solar output from the PVWatts tool, UK unit rates and typical use from Ofgem, UK solar output from the European Commission PVGIS tool, and UK installed prices from the Department for Energy Security and Net Zero. The methodology page lists every figure with its source link and the date it was checked.
Why do I need to enter a price for a US system?
We only use figures we can check against a primary source. A US installed-price figure has not been verified yet, so the US calculator asks for the price on your quote. Until you enter one, it shows generation and savings but not payback.
Does the calculator count payments for power sent to the grid?
No. It values only the electricity your home uses instead of buying it. Anything sent to the grid is valued at zero. If you are paid for exported power, your real payback will be shorter than the estimate.
What costs are left out?
Maintenance, replacement parts such as inverters, loan interest and the time value of money are not included. The installed price you enter is treated as a single payment at the start.
Are my figures stored?
No. The calculator runs in your browser and the figures you type are not sent to us.

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