HOMEOWNER GUIDE · REVIEWED 9 OCTOBER 2026

Solar payback: calculate it without the sales guesswork

Simple payback is the installed cost divided by estimated annual net savings. It is a useful comparison, not a guaranteed return.

A worked illustration

If a system costs £8,000 and saves £800 each year after recurring costs, simple payback is 10 years. If savings are £500, it is 16 years. These are arithmetic examples, not forecasts for your home.

Build the annual saving

Separate electricity used in the home from exported electricity. Use your actual tariff and an available export rate. Include standing charges only if they genuinely change, and allow for maintenance and possible equipment replacement.

Compare the assumptions

Ask for generation, shading, self-consumption, export, tariff inflation and degradation assumptions. A battery can change self-consumption and time-of-use savings, but also adds cost and losses. Compare the incremental battery case separately.