Tariffs

Cheap overnight tariffs and home batteries

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

How it works

You need a smart meter and a tariff with a cheap window. The battery fills inside that window and you use the stored power at the dear times. Some batteries run this on their own. Others need a schedule set in an app.

Not every tariff is open to every home, and some are built around a car or a heat pump. Read a tariff's eligibility rules before you buy a battery for it.

Real rates, South Eastern England, 7 October 2026

From Octopus Energy's public tariff data for the South Eastern region (region J), Direct Debit, VAT at 0%:

• Intelligent Octopus Go, 12-month fixed: 7.6p per kWh at night and about 37.7p by day. The listing shows a £50 exit fee.
• Octopus Go, variable: about 8.2p per kWh in the cheap window, 00:30 to 05:30 British Summer Time, and about 29.9p otherwise.
• Octopus Go, 12-month fixed: 9.5p cheap and about 36.3p otherwise.
• Cosy Octopus: about 12.6p cheap, about 25.7p standard and about 38.5p at peak.

Rates and eligibility change. Treat this as a snapshot from one morning, not a promise.

Look at the spread. The night rate on these tariffs is between about 7.6p and 12.6p, and the dearest rate is about 38.5p. That is a gap of roughly five times, which is why a battery set to the clock can look clever. It is also why a badly set one can cost you money.

The honest sums

Our model uses 10p for the cheap rate. Charge at 10p, lose about 10% in the battery, and a unit costs you about 11p. Use it in place of a unit at the 26.32p price cap and each one saves about 15p (our arithmetic). Over a year a 5 kWh battery saves roughly £230.

At £2,750 to £4,750 installed, payback is about 12 to 21 years, longer than the 10 to 12 years the Energy Saving Trust gives as a typical battery life. Put the battery on solar as well and the cheap rate roughly doubles the saving compared with no tariff, from about £110 to about £230 a year. That is better. It is not magic.

Watch the day rate

Several of these tariffs have day rates well above the 26.32p price cap. A home that charges a battery at night but still uses a lot of power in the day, away from the cheap window, can end up paying more overall. The sum only works if the battery covers your expensive hours. Check your own bills, not the headline night rate.

A short checklist

1. Get a smart meter if you do not have one. The tariffs need half-hourly readings.
2. Read your last year of use and split it into day and night as best you can.
3. Look up the tariff's eligibility rules and the exit fee, if there is one.
4. Set the battery to fill inside the cheap window and check on a real night that it did.
5. Review after three months. Rates move, and so does your use.

Where it is strongest

Think of the battery as a small tank and the car or heat pump as the thing that really drinks. A 5 kWh battery covers a modest evening. A car can take several times that in one night, straight from the cheap window, with no battery in the way. Tariffs like these suit a home with a lot of flexible load: an electric car that charges overnight, or a heat pump. In those homes the cheap window is used every night. See the EV guide.

Questions people ask

Sources

• Octopus Energy: public tariff data (product list)
• Octopus Energy: Intelligent Octopus Go
• Ofgem: changes to the energy price cap, 1 October to 31 December 2026
• Energy Saving Trust: battery storage

More guides

• What solar and a battery cost for a Faversham house
• Is a home battery worth it?
• What size solar and battery do I need?
• Solar only, battery only, or both?
• 0% VAT on solar and batteries, and what it means
• Planning permission and network approval in Faversham
• Pairing an EV charger with solar and battery
• Smart Export Guarantee: real rates, October 2026
• Solar by house type in Faversham