Guide

How EV tariffs and home batteries work together

Quick answer

How does a battery make an overnight EV tariff go further?

A time-of-use tariff charges less for electricity at off-peak times, usually overnight. A home battery fills up at that low rate and powers the house through the expensive peak hours, while the car charges overnight too. Both the house and the car then buy most of their electricity at the cheaper rate, not the peak one.

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Technician fitting a wall-mounted home battery system indoors

How time-of-use tariffs work

Several suppliers offer tariffs with a cheaper rate for a few hours each night and a standard or higher rate for the rest of the day. The times and rates vary by supplier and change often.

For that reason we check what is available when we prepare your quotation, rather than recommending one tariff for everyone.

Tablet on a kitchen worktop, used to check home energy settings

What the battery adds

Without a battery, only the things you run overnight benefit from the cheaper rate. With a battery, the house can run on stored off-peak electricity through the day and evening, including the peak hours when electricity costs most.

If you also have solar panels, the battery stores daytime surplus as well, so less is exported for a low payment and more is used at home.

Making it automatic

A smart charger and a battery with a good app can follow your tariff automatically. The car charges in the off-peak window, the battery fills at the same time, and you do not need to remember to do anything.

You can still override the schedule when you need a full charge in a hurry, and the system goes back to its normal routine afterwards.

We install through MCS-certified partners across Scotland. Your postcode decides whether SP Energy Networks or SSEN is your network operator, and the network approval is handled as part of the process.

Reviewed by the Scottish Energy Efficiency team. Last updated: 28 October 2026.

FAQ

Frequently asked questions

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What is a time-of-use tariff and how does it help?

A time-of-use tariff offers cheaper electricity during off-peak hours, usually overnight. A home battery charges at the cheap rate and discharges during peak hours, so both your house and car buy power at the low rate instead of the high one.

How much can a battery save on an EV tariff?

It depends on the gap between your day and night rates, how much electricity you use at peak times and the battery size. Your quotation shows the assumptions so you can check them against your own bills; we do not quote a standard figure.

Can a battery charge my EV at the cheap rate?

Yes. The battery stores cheap overnight power, and the car can draw from the battery or charge directly during the off-peak window. A smart charger coordinates both so the house and car use the cheapest available electricity.

Which EV tariffs are available in Scotland?

Several suppliers offer overnight time-of-use tariffs in Scotland. The rates and off-peak windows change often, so we check what is available at the time of your quotation rather than recommending a single tariff.

Do I need a smart meter for a time-of-use tariff?

Yes. Time-of-use tariffs need a smart meter so the supplier can measure when you use electricity. If your smart meter is not communicating, it needs to be fixed by your supplier before you can switch.

Keep reading

Related guides

More on solar, batteries and EV charging in Scotland.

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