Home battery storage is a battery, usually lithium-ion, fitted in a house or garage to store electricity and release it when it is needed. It charges from rooftop solar panels, from the grid at cheaper times, or both, and an inverter converts the stored power for use in the home.
Sizing: kWh and kW
Two numbers describe a home battery:
| Rating | What it tells you |
|---|---|
| Usable capacity (kWh) | How much energy it can store and give back |
| Power (kW) | How much it can supply at once, which limits how many appliances it can run together |
A sensible size starts from how much electricity you use in the evening and overnight, not from the size of your solar array. For example, a household that uses about 5 kWh between late afternoon and the next morning gains little from a battery much bigger than that, unless it plans to charge from the grid and use the battery through the day. Usable capacity is often lower than the headline capacity, so it is worth checking which figure is quoted.
Pairing with solar or a time-of-use tariff
- With solar panels, a battery stores daytime surplus that would otherwise be exported, so more of your own generation is used at home. That can matter more than export payments, because the price you pay for imported electricity is usually higher than the rate you are paid for exports.
- With a time-of-use tariff, a battery can charge when grid electricity is cheapest, often overnight, and power the home during the more expensive peak. This works with or without solar panels.
Savings depend on your tariff, usage pattern and installation cost, so a battery does not pay for itself in every home. This is general information, not financial advice.
VAT relief
Since 1 February 2024, batteries installed in residential accommodation qualify for the zero rate of VAT on energy-saving materials, according to HMRC. This covers batteries fitted alongside solar panels, retrofitted to an existing system, or installed on their own to store grid electricity. The zero rate is temporary and currently runs until 31 March 2027. The installer applies the VAT rate, so there is nothing to claim back yourself.
Read more: Solar panels for your home in the UK: costs, savings and how they work.