A home battery without solar: the sums
It can pay if you're already on a cheap overnight rate like Octopus Go and the battery moves the rest of the house onto it, but even then the payback is close to the working life of the battery, so on its own it's hard to justify.
Econotion · Updated 1 November 2026 · From published pricing and specifications. We don't run a home battery ourselves.
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On our sums a 5 kWh battery charged at Go's night rate and used during the day comes out about £410 to £495 a year better off, as long as it's emptied most days. At about £4,600 installed that's a 9 to 11 year payback, and the Energy Saving Trust puts battery life at around 10 to 12 years. On Agile, without an EV, the numbers are weaker.
Go and Agile are only open to Octopus customers. If you're not with them yet you join on a standard tariff first and move across once they've connected to your smart meter, which Octopus says takes around 14 days.
How it works without solar
The battery charges from the grid when electricity is cheap and runs the house when it's expensive, which is how the Energy Saving Trust describes using one. You lose some energy charging and discharging, so each kWh you get back costs a bit more than the kWh you bought.
Tesla publishes a round-trip figure of 89% for the Powerwall 3, and we've used 89% throughout as the other makers mostly don't publish one.
Popular home batteries in the UK
These are the batteries UK installers are quoting most in 2026. Octopus fits three of them itself, and its battery-only prices are the most useful benchmark because they're published.
| Battery | Usable capacity | Power | Warranty | Installed price |
|---|---|---|---|---|
| Tesla Powerwall 3 | 13.5 kWh, expandable to 94.5 kWh | up to 11.04 kW out, 5 kW charging | 10 years, as long as it stays online | £7,999 fitted by Octopus |
| Fox ESS EVO | 10.24 kWh, 95% usable (about 9.7 kWh) | 5, 8 or 10 kW inverter | 12 years | from £5,336 fitted by Octopus |
| Enphase IQ Battery 5P | 5 kWh per unit, stackable | 3.2 kVA per unit | 15 years or 6,000 cycles, to above 60% capacity | Octopus fits two for its £5,336 10 kWh option |
| Anker SOLIX X1 | 5 kWh modules, up to 30 kWh per inverter | 3.6, 5 or 6 kW inverter | 10 years | from about £3,700 for 5 kWh with the inverter, fitted |
| Sigenergy SigenStor | 5.2 or 7.8 kWh modules, up to about 48 kWh | 3.6 to 12 kW (single phase) | 10 years to 70% capacity, or a throughput limit | about £6,995 for around 13 kWh |
| AlphaESS SMILE G3 | 4.56 or 9.3 kWh modules, 95% usable | 3.68, 5 or 8 kW | 10 years to 80% capacity | about £3,950 for 10.1 kWh supplied and fitted |
Octopus's battery-only prices start at £3,947 for 5 kWh (a Fox EVO or one Enphase unit), £5,336 for 10 kWh and £7,999 for a Powerwall 3, and it can fit a battery without solar in most homes. The Anker, Sigenergy and AlphaESS prices come from installer price guides rather than a price the maker publishes, so treat them as a rough guide. Batteries fitted in homes are 0% VAT until 31 March 2027.
A few things to check on any quote:
- whether the price includes the inverter, as some quotes are for the battery alone
- whether backup in a power cut is included, as the Powerwall 3 needs Tesla's Backup Gateway 2 and the Fox EVO needs Fox's EPS-BOX gateway for whole-home backup
- how fast it charges, as a battery on Go needs to fill inside five hours (a Powerwall 3 at 5 kW takes about 2.7 hours)
- what capacity the warranty guarantees at the end, which varies from 60% to 80%
- where the installer plans to put it, as the rules on battery locations changed in October 2026 (see below)
GivEnergy. GivEnergy used to be one of the most popular brands in the UK, but GivEnergy Ltd went into administration on 9 April 2026 and the administrator has said hardware warranties won't be honoured. Installed batteries keep working and the app is run by a separate company that isn't in administration, but don't buy leftover stock on the strength of the 12-year warranty.
Octopus has also announced its own batteries, the Nook range: the Nook Colossus, a wall-mounted 5 or 10 kWh unit that stacks to 30 kWh, and the Nook Cube, a 2 kWh plug-in unit aimed at renters that expands to 10.5 kWh, both with a 12-year warranty. Octopus says they go on sale in 2027.
Which tariff you'd use
On Octopus:
- Octopus Go needs an EV charged at home, and if you have one a battery lets the whole house run on the night rate.
- Flux and Intelligent Flux both need solar, so they aren't open to a battery-only home.
- Agile is the tariff Octopus points battery-only owners to, with prices changing every half hour.
We haven't been able to confirm which other suppliers' tariffs accept a battery with no solar or EV, so check before you buy.
The figures on Octopus Go
Using Octopus's published South Scotland rates for the Go fix available from 30 October 2026, with 0% VAT, of 9.4p/kWh at night and 37.81p/kWh during the day, a 5 kWh battery works out like this:
- filling it takes 5 ÷ 0.89 = 5.6 kWh at 9.4p, about 53p
- emptying it replaces 5 kWh at 37.81p, about £1.89
- the difference is about £1.36 a day
That's about £495 if it's emptied every day of the year, or about £410 if it's fully used on 300 days, which is more realistic. The Energy Saving Trust puts a 5 kWh system at around £4,600, so that's a 9 to 11 year payback, and against Octopus's £3,947 for 5 kWh it's closer to 8 to 10 years. These are our calculations, not an Octopus figure.
Two things push that the wrong way:
- a typical home uses about 7.4 kWh a day and some of that already falls overnight, so a bigger battery won't get fully used
- the Energy Saving Trust quotes two different price ranges on two different pages (£1,500 to £10,000, and £5,000 to £8,000), so a quote could come in well above £4,600
The figures on Agile
On the day we looked at in detail, 24 September in London, overnight Agile prices were about 24 to 27p/kWh, the midday low was 17p and the 4pm to 7pm peak was 39 to 49p, all including the 5% VAT that applied then. The useful gap is between the cheap slots and the evening peak, and a typical home only uses 2 or 3 kWh in those three hours.
At that spread, after losses, it comes to roughly £150 to £300 a year, a 15 to 30 year payback on a £4,600 battery. Plunge pricing days or very cheap nights would help, but you'd need a full year of data to get a reliable figure.
Other things to check
- Where it goes: Amendment 4 of the wiring regulations (BS 7671) is now the current edition, as the IET confirms, and the transition period for the previous edition ended on 15 October 2026. Installer guides say it rules out lofts, bedrooms and escape routes for home batteries and sets minimum distances from doors and windows outside, so ask the installer where it will go and check the quote reflects that.
- Export: suppliers don't have to pay for exporting electricity that came from the grid rather than from renewables.
- Grid rules: a battery counts towards connection limits, so up to 3.68 kW per phase goes through the simpler G98 process and above that it needs G99 approval from your network operator, which Octopus says it handles for its installs.
- VAT: batteries installed in homes are 0% VAT until 31 March 2027, standalone batteries charged from the grid included, and it goes back to 5% after that.
Checking a quote
We wouldn't buy a battery for this alone. If you're already on Octopus Go for the car and a 5 kWh quote comes in well under £4,600, it starts to make sense. To check a quote, take the usable kWh, multiply by 300 days and by (day rate minus night rate ÷ 0.89), then divide the installed price by the result, and if that's more than about 10 years the battery is unlikely to pay for itself before it wears out.
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