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Cheap overnight tariffs and a battery only

Last reviewed 7 October 2026. Written for Broadstairs, Kent. Figures are estimates, not quotes.

Short answer. A time-of-use tariff has cheap and dear times. A battery charges when power is cheap and gives it back when it is dear. We estimate a 5 kWh battery saves about £180 to £270 a year this way, at an example 10p cheap rate.
White wall-mounted home battery beside a consumer unit with neat grey conduit on a brick garage wall
In this guide

How it works

You need a smart meter. The battery charges at night, or whenever power is cheapest, and you use it in the evening peak. Some batteries follow a smart tariff on their own. Others need a schedule.

The honest sums

Say you charge at an example 10p and use that power in place of the 26.32p price cap. After about 10% loss, each unit saves about 15p. A 5 kWh battery cycling on about 330 days might save £230 a year on our model. A 10 kWh battery saves little more in a typical home, because evening use is the limit. We do not quote supplier tariff rates here because they change: check the tariff you are offered.

On a price of £2,750 to £4,750, that is a payback of about 12 to 21 years, against a battery life of about 10 to 12 years (Energy Saving Trust). Treat it as a long-term choice, not a quick saving.

A route for flats

A battery needs no roof. If you own a flat and can put a battery inside, with the freeholder's agreement, a cheap overnight tariff is the only way it can earn. The saving is modest. Our estimator will show it.

When it is strongest

It is strongest with an electric car or heat pump, which use a lot at cheap times. The Energy Saving Trust says a battery can also run a heat pump together with a smart time-of-use tariff.

Questions people ask

Do I need a smart meter?

Yes. Time-of-use tariffs need half-hourly readings from a smart meter.

Can I use a cheap tariff with no solar?

Yes for a battery, if you meet the tariff rules. Some tariffs need an electric car or heat pump.

Is there an exit fee?

Some fixed tariffs have one. Check before you switch.

Want numbers for your own home? Try the estimator or ask for a free quote.

Sources

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