Home Batteries: When They Pay Off, and When They Don't
A home battery sounds like the obvious partner for solar panels: store the sunshine, use it at night. Sometimes that is exactly right. Sometimes it is an expensive extra that takes a very long time to pay back. Here is how to tell the difference.
What a battery actually does
Your panels make power at midday, but many homes use most of their electricity in the morning and evening. Without a battery, a typical home uses around 40% of what its panels produce. With one, that can rise to 70 to 80%. The rest of the sunshine is either sold to the grid or, with a battery, saved for later.
The money maths in one line
A battery earns its keep by the gap between what you pay to buy power and what you are paid to export it. In the UK, with imports around 26p per kWh and export payments around 12p, each stored kWh is worth roughly 14p. A typical 10 kWh battery costs about £4,000 to £6,500 installed and pays back in roughly 9 to 14 years. In Germany and Italy the gap works the same way: the bigger the difference between your bill price and your export payment, the better a battery looks.
When a battery tends to pay off
- You use little power during the day (everyone out at work) so a lot of your solar would otherwise be exported.
- You are on a time-of-use tariff, where you can charge cheaply overnight and use it at peak times.
- You have, or soon will have, an EV or heat pump with evening or overnight demand.
- You plan to stay in your home for eight years or more.
When it probably does not
- Someone is home most days and already uses much of the solar directly.
- Your export payment is already close to what you pay for imports.
- Your system is small, so there is little surplus to store.
- You mainly want it for blackout backup (that is a fine reason, just not a savings one).
Good to know
In the UK, 0% VAT applies to batteries installed with solar until March 2027. A battery can also usually be added later, so you do not have to decide on day one. Prices and warranties vary a lot between brands, so compare quotes carefully.
Your next step
The honest answer depends on your roof, your habits and your tariff. Try the free Solar Roof Planner below to see your estimated output and a battery sense-check for your own home. No sign-up, no pressure.