Cheap overnight tariffs and home batteries

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

Short answer. Charging a battery at a cheap overnight rate and using it later is how a battery works without solar. Octopus lists Intelligent Octopus Go at 7.6p per kWh. Our model gives 12 to 21 years payback for 5 kWh on existing solar with a 10p rate, and 12 to 21 years with no solar.

White wall-mounted home battery next to a small consumer unit on a whitewashed garage wall, with a bicycle and a coiled cable

In this guide

How it works
Rates we read
The honest sums

How it works

You need a smart meter and a tariff with a cheap period, usually overnight. The battery fills when power is cheap, then supplies the house when the daytime rate is higher. You save the gap, less the 10% the battery loses.

Rates we read

Octopus's Intelligent Octopus Go page lists smart charging of eligible cars from 7.6p per kWh, with six hours of cheap power each night between 11:30pm and 5:30am, and it says only fixed rates are on offer at the moment. Cosy Octopus needs a heat pump, electric radiator or electric boiler and gives cheap windows 51% below the day rate. Both are examples, not recommendations, and your own rates depend on your region.

The honest sums

With a 10p cheap rate against 26.32p, 5 kWh with no solar is about £2,750 to £4,750 for a saving of about £180 to £270 a year, payback 12 to 21 years in our model. That is better than a battery added to solar with no tariff change, but it is still long next to a 10 to 12 year life.

Questions people ask

Do I need an electric car?

Not for every cheap tariff, but Intelligent Octopus Go needs an eligible car or charger.

Is the cheap rate guaranteed?

No. Tariffs change, and only fixed rates were on offer on the Intelligent Octopus Go page we read.

Can I use it with solar?

Yes. The battery takes solar by day in summer and the cheap rate in winter.

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

Cheap overnight tariffs and home batteries

How it works

Rates we read

The honest sums

Questions people ask

Sources

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