Solar battery storage

What a battery does

Solar panels generate most in the middle of the day, when many homes use the least. Without a battery, spare power is exported to the grid and earns a Smart Export Guarantee (SEG) rate, around 12p/kWh according to the Energy Saving Trust. With a battery, you store it and use it later instead of buying electricity at up to 26.32p/kWh (the Ofgem price cap rate for 1 Oct to 31 Dec 2026).

The gap between those two prices is where a battery's value comes from. Some households also charge batteries from the grid overnight on a cheaper time-of-use tariff.

What do batteries cost? (sourced ranges)

Source: Checkatrade solar battery cost guide, updated June 2026. The Energy Saving Trust gives a range of £5,000 to £8,000. Your quote will depend on brand, inverter setup and installation.

0% VAT until 31 March 2027

Under HMRC VAT Notice 708/6, solar panels and batteries installed in homes are zero-rated for VAT from 1 May 2023 to 31 March 2027. That includes batteries added to an existing solar system. From 1 April 2027 the rate is due to become 5%.

When is a battery worth a closer look?

• You're out during the day and use most of your electricity in the evening.
• Your panels already export a lot of what they make.
• You're on, or would switch to, a time-of-use tariff.
• You have or plan an EV or heat pump.

It's less likely to pay off if someone's home all day using the solar directly, or if your system is small. Ask for numbers with and without a battery.

Sizing a battery

Bigger isn't always better. A battery that never fills on a typical day is money you didn't need to spend. Installers usually size against your evening and overnight use and your system's output. Ask how they've sized it, what usable capacity (not just total capacity) you'll get and what the warranty covers.

Battery questions