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
Installed cost
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Est. annual saving
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Payback
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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.