A home battery stores spare solar power (or cheap night-time power) so you can use it later. The right size depends on how much you use in the evening.
Look at how much electricity you use from late afternoon to bedtime. That's what a battery can cover. Your smart meter app or bill shows your use in kWh (kilowatt hours, the units on your bill).
Sources: Energy Saving Trust, Battery storage, checked 25 Oct 2026; Which?, checked 25 Oct 2026
The Energy Saving Trust puts battery systems at £1,500 to £10,000, with a 5 kWh system around £4,600 Estimate. Batteries last about 10 to 12 years.
Which? puts costs from under £2,000 to £10,000. Batteries usually come with a 10-year warranty. Over a solar system's 25+ years, you're likely to need to replace the battery at least once.
Payback could take many years. It depends on your tariff, your usage and the install price. A battery doesn't always pay for itself, so ask each installer for their saving estimate in writing.
Sources: Energy Saving Trust, Battery storage, checked 25 Oct 2026; Which?, checked 25 Oct 2026
Batteries fitted in your home have 0% VAT until 31 March 2027, then 5%.
Source: HMRC VAT Notice 708/6. Checked 25 Oct 2026
Start with what solar could make on your roof. Our battery calculator is coming soon.
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