Battery size finder
Find the right battery size for your UK home. Match usable capacity to your actual electricity usage — with or without solar. Free, no email.
Savings assume a smart tariff with cheap overnight units. Not a quote.
Our recommendation
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In this size class
How the sizing works
A battery only pays for itself on the energy it actually shifts. We size for your evening and overnight use — roughly 45% of a typical day — plus headroom for an EV or heat pump, then snap to the usable capacities batteries actually ship in.
With solar, the battery stores your spare generation instead of exporting it at 15p and buying it back at 27p. Without solar, it charges cheap overnight on a smart tariff and covers your peak hours — the maths still works, just more slowly.
Bigger is not better. Capacity you don't cycle daily is dead money — if you're between sizes, take the smaller one.
Common battery sizing questions
Most UK homes do well with 5-10kWh of usable capacity. The sweet spot balances daily cycling against having enough for your evening usage. Our size finder matches capacity to your actual annual usage. Oversizing means paying for capacity you never cycle.
Yes — if you're on a time-of-use tariff. Charging at 7p/kWh overnight and using it during the day saves about 18p per kWh shifted. A 10kWh battery cycling daily saves roughly £650/year. Read our battery without solar guide.
Modern LFP batteries are warrantied for 6,000-10,000 cycles — 16-27 years of daily cycling. Most guarantee 70-80% capacity at 10 years. Expect 15-20 years of useful life from a quality battery.
Related guides
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