A home battery shifts when you buy electricity, not how much you use. Typical domestic units hold around 5 to 15kWh, so treat one as a meaningful top-up for the car and a bill-shifting tool — not a way to refill a 60kWh EV every night. Last reviewed: 19 August 2026.
What home battery storage actually does
A home battery stores cheap or self-generated electricity and gives it back when power is expensive. On a time-of-use tariff you charge overnight at the low rate and run the house through the evening peak on stored energy. With solar, it holds the daytime surplus instead of exporting it for pennies.
It does not make electricity. The savings come entirely from the price difference between when you buy and when you use — which is why the tariff matters as much as the hardware.
Sizing it sensibly
Start with your actual consumption, not a salesperson's default. A typical UK home uses somewhere between 8 and 12kWh a day, and most of that outside the cheap window. A battery sized to cover your evening and morning use is usually the sweet spot; anything larger sits half-empty and never pays for itself.
If you have an EV, the sums change. Charging the car overnight at the off-peak rate is usually the bigger saving, and the house battery is the smaller piece on top.
Costs, payback and the practical side
Installed costs vary widely with capacity, inverter and whether solar is included. Payback depends on the tariff spread, how much you use in peak hours and whether you also run an EV. Get more than one quote and ask each installer to show the assumptions behind their saving figure.
Practically: batteries need a ventilated, frost-free location with space around them, the installer must be properly certified, and the DNO notification has to be done. Check the warranty in cycles as well as years, and what the guaranteed remaining capacity is at the end of it.
Frequently asked questions
Do I need solar panels for a home battery?
No. On a time-of-use tariff you can charge overnight at the cheap rate and use it during peak hours. Solar adds to the saving but is not required.
What size battery do I need?
Enough to cover your evening and morning use outside the cheap window — typically a fraction of daily consumption, not all of it.
How long do home batteries last?
Warranties are usually quoted in both years and cycles, with a guaranteed remaining capacity at the end. Read both figures before comparing prices.
Does it work in a power cut?
Only if the system is specified with backup capability. Many standard installations shut down with the grid.