Solar Payback Calculator

Calculate how long a solar system takes to repay its cost through bill savings.

About Solar Payback Calculator

Simple payback divides the up-front cost by the recurring annual benefit to get the number of years before the solar system has paid for itself. Everything after that point is net gain, which the lifetime figures make explicit. Payback is the first screen most buyers apply: a system that pays back inside its warranty period is a very different proposition from one that does not.

Formula

Solar Payback

Payback (years) = Installed cost after any grant ÷ annual annual bill saving

Installed cost after any grant: Up-front cost
Annual bill saving: Recurring saving or return per year

Worked example

With the default values below, Solar Payback Calculator returns Payback Period of 7.13. Change any input above and every figure here is recalculated in your browser.

Inputs used

Installed cost after any grantminimum 0: 8,200
Annual bill savingminimum 0: 1,150
Expected lifeaccepts 1–60 years: 20 years

Results

Payback Period: 7.13 years
Payback Period: 85.6 months
Lifetime Saving: $23,000.00
Net Lifetime Benefit: $14,800.00
Lifetime Return: 180.5%

Step by step

1Values used
2Solar Payback
3Payback Period= 7.13 years
4Payback Period= 85.6 months
5Lifetime Saving= 23,000.00
6Net Lifetime Benefit= 14,800.00
7Lifetime Return= 180.5

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation or tax into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Solar Payback calculated?

Payback (years) = Installed cost after any grant ÷ annual annual bill saving Simple payback divides the up-front cost by the recurring annual benefit to get the number of years before the solar system has paid for itself. Everything after that point is net gain, which the lifetime figures make explicit.

Why does Solar Payback matter?

Payback is the first screen most buyers apply: a system that pays back inside its warranty period is a very different proposition from one that does not.

What values do I need to enter?

This calculator takes 3 inputs: Installed cost after any grant, Annual bill saving, Expected life. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.