A home battery without solar earns only on price gaps. Over the 12 months to 13 October 2026, a 10 kWh battery on Agile Octopus would have saved £239 to £266 a year on its own for a home using 3,000 kWh, or £268 to £346 against Flexible Octopus once the tariff switch is counted. At Octopus's £5,336 for 10 kWh that is a payback of about 15 to 20 years on the total and 20 to 22 on the battery's own saving. Octopus Go pays more but needs an electric car; British Gas Charge Power is the battery-owner tariff that does not.
How a battery earns without panels
With no solar, a battery has one job: buy electricity when it is cheap and use it when it is dear. Each kWh it shifts saves the difference between the two prices, minus about a tenth lost in charging and discharging. Over a year, the saving is that gap multiplied by how many kWh the home can actually use outside the cheap hours.
So two things decide whether it pays: the size of the price gap your tariff offers, and how much electricity you use when prices are high.
Which tariffs allow it
| Tariff | Can a battery-only home use it? | Rates on 14 October 2026 (London, including VAT) | Conditions |
|---|---|---|---|
| Agile Octopus | Yes, with a smart meter | Half-hourly; 12-month average 20.3p; evenings 4pm to 7pm averaged 35.2p | A SMETS2 meter, or a Secure SMETS1; prices published between 4pm and 8pm for the next day, capped at 100p |
| British Gas Charge Power | Yes, for any home battery, with or without solar | Half price from midnight to 5am; unit rates not published on the page | A British Gas account, smart meter sending half-hourly readings, fixed Direct Debit |
| Octopus Go | No: needs an electric car charged at home | Variable 8.21p from 00:30 to 05:30 and 29.52p otherwise; 12-month fixed (launched 14 October 2026) 9.40p and 37.29p | Smart meter; £50 early exit fee |
| Intelligent Octopus Go | No: cars and chargers; no battery mention | Six hours off-peak, 23:30 to 05:30 | A compatible car and charger; £50 early exit fee |
| Cosy Octopus | No: needs a heat pump, electric boiler or electric radiators | Variable 12.44p in three daily windows, 25.36p standard, 38.04p from 4pm to 7pm | Smart meter |
| Octopus Flux | No: needs solar and a home battery | Cheap 02:00 to 05:00, peak 16:00 to 19:00 | Octopus requires solar panels and a home battery, an export meter and the MCS certificate |
| Snug Octopus | No: storage heaters only | 8.57p from 00:30 to 06:30 | Storage heaters a smart meter can control |
Other suppliers have overnight tariffs too, mostly for electric vehicle owners. If you add solar later, a battery already on the wall can join Octopus Flux once the panels have an MCS certificate; the retrofit solar battery guide models the payback, and the Octopus Flux rates page lists what Flux pays in each region.
What Agile looked like over 12 months
The chart above averages every half-hour of Agile Octopus prices in London over the 365 days to 13 October 2026. The pattern is steadier than a 30-day sample suggests. The evening peak, 4pm to 8pm, averaged 28p to 35p in every season. The cheapest hours are overnight in winter (about 14p to 15p from midnight to 6am from November to March) and around midday in summer (about 13p from noon to 4pm from April to September), because summer solar across the grid pushes wholesale prices down. The 12-month average was 20.3p, the dearest half-hour was 86.7p and the cheapest was minus 11.3p: in London, 484 half-hours, or 2.8% of the year, were priced below zero.
Prices on Agile are announced the afternoon before, so a battery can plan a full day ahead. Across all 14 regions the pattern is the same, but not the level: the 12-month average ranged from 20.3p in London to 24.4p in North Scotland.
What the battery would have saved: a 12-month back-test
To replace guesswork with data, we ran a simple battery over every day of the year. The home uses 3,000 kWh a year, with the same seasonal shape and evening-peak share as this site’s calculator; the battery holds 10 kWh, delivers 90% of what it stores, charges and discharges at up to 5 kW, covers only the home’s own use (no export) and does at most one full cycle a day. For each day it knows that day’s prices, charges in the cheapest half-hours and discharges in the dearest while the gap beats the charging loss. Standing charges are the same with or without the battery, so they are left out.
| Region | Battery’s own saving on Agile | Agile against Flexible, no battery | Total against Flexible |
|---|---|---|---|
| Eastern England | £254 | £79 | £333 |
| East Midlands | £256 | £69 | £324 |
| London | £239 | £105 | £343 |
| Merseyside and North Wales | £261 | £85 | £346 |
| West Midlands | £245 | £59 | £304 |
| North East England | £245 | £54 | £299 |
| North West England | £245 | £93 | £339 |
| Southern England | £245 | £87 | £333 |
| South East England | £252 | £67 | £319 |
| South Wales | £252 | £61 | £313 |
| South West England | £250 | £39 | £289 |
| Yorkshire | £247 | £77 | £324 |
| South Scotland | £254 | £61 | £315 |
| North Scotland | £266 | £3 | £268 |
The first column is the battery’s own contribution: the same home on Agile with no battery, against the same home with one. The second is what moving to Agile saves (or costs) a home that cannot shift anything, measured against Flexible Octopus at its published rates. The third is the two together, which is the figure this site’s calculator reports. Be careful with it: part of that total is the tariff, and a home could take it without buying a battery.
What the table shows:
- The battery’s own saving is steady, about £240 to £265 in every region. It depends on the evening spike and the overnight dip, and those are much the same everywhere.
- The tariff effect is not. London homes would have saved £105 by switching to Agile before buying anything; North Scotland homes £3. Regions with a higher Flexible rate gain most from Agile’s cheaper hours.
- The battery worked hard. It completed about 204 full-cycle equivalents over the year, roughly 56% of days at a full 10 kWh, because a 3,000 kWh home uses about 8 kWh a day and some of that falls in the cheap hours when no battery is needed.
- Winter and summer are close. In London the battery’s saving averaged about 70p a day from November to March and about 53p from April to August, with September 2026 the best month at about 86p a day.
- Negative prices barely matter. Charging while Agile was paying customers to use power added only about £6 to the year’s saving, because the battery was already filling at low prices.
The back-test lands in the same range as this site’s calculator, which uses a 30-day average Agile profile and gave £335 for London and £222 for North Scotland. The real year was a little better in both: £343 and £268.
Size and usage change the answer
Running the same back-test for London with other batteries and household use gives the battery’s own saving each year:
| Household use | 5 kWh | 10 kWh | 13.5 kWh | 20 kWh |
|---|---|---|---|---|
| 2,000 kWh a year | £159 | £161 | £161 | £161 |
| 3,000 kWh a year | £225 | £239 | £239 | £239 |
| 4,500 kWh a year | £310 | £347 | £354 | £354 |
| 6,000 kWh a year | £355 | £442 | £459 | £467 |
Below about 4,500 kWh a year a 5 kWh battery gets most of the saving: at 3,000 kWh it earns 94% of what a 10 kWh battery does. Above 10 kWh adds nothing until use reaches about 4,500 kWh a year. A faster charge rate barely helps either: raising the limit from 2.5 kW to 7 kW lifted the 10 kWh result only from £234 to £241.
Each region’s tariff rates and modelled battery savings are on its regional page, and the calculator runs your own usage.
The Go and Cosy numbers, for households that qualify
Octopus Go’s cheap window is five hours, 00:30 to 05:30, and its page says you must have an electric car that you charge at home. Octopus’s API shows Go 12M Fixed available from 14 October 2026, and its page says only fixed rates are currently offered; the API still lists the variable product too. This site’s model gives these yearly savings for a 3,000 kWh home with a 10 kWh battery and no solar, against Flexible Octopus on 14 October rates:
| Region | Go variable (8.21p night) | Go 12M Fixed (9.40p night) |
|---|---|---|
| London | £510 | £466 |
| Merseyside and North Wales | £547 | £503 |
| Yorkshire | £481 | £437 |
| South West England | £510 | £466 |
| North Scotland | £503 | £459 |
The fixed product’s day rate is far higher (37.29p in London, against 29.52p on the variable tariff), so a small battery can leave a home worse off: the same London home with 5 kWh saves only £120 on the fixed product, because most of its use is still billed at 37p. On Go the battery needs to be big enough to move nearly all your use. The EV’s own charging at the cheap rate is a separate saving that the battery does not create.
British Gas Charge Power: the battery-owner tariff that does not need a car
British Gas’s Charge Power tariff is built for homes that already have a battery, with or without solar. Its page says electricity used between midnight and 5am gets a 50% discount on the unit rate, the full daily standing charge still applies, it works with all batteries, and customers can export through the Smart Export Guarantee at up to 12p a unit. It needs a British Gas account, a smart meter sending half-hourly readings and a fixed Direct Debit.
The page does not publish the unit rates, so we have not modelled it. The arithmetic you can do without them is simple: a unit stored at half the day rate and delivered at 90% costs about 56% of the day rate, so each kWh the battery moves saves about 44% of the day rate. At a 30p day rate that is 13p per kWh delivered; at 34p, 15p. Multiply by the kWh you can move, then compare the whole-year bill, standing charge included, with the best flat tariff you could get, not just with Charge Power’s own day rate.
The honest payback
Octopus lists a 5 kWh battery-only installation from £3,947 and a 10 kWh one from £5,336 at April 2026 prices. Using London’s back-test:
| Battery | Price | Own saving | Payback on own saving | Payback including the tariff gain |
|---|---|---|---|---|
| 5 kWh | £3,947 | £225 | 17.5 years | 12.0 years |
| 10 kWh | £5,336 | £239 | 22.3 years | 15.6 years |
At the official median installed price for a 6 to 11 kWh battery (£890 per kWh in 2025/26, so £8,900 for 10 kWh) the paybacks are longer still: about 37 years on the battery’s own saving and 26 including the tariff. Most batteries carry 10 to 15 year warranties, so a 22-year payback is a bet on both prices and tariffs lasting. The smaller battery is the better buy on these numbers.
It gets better when:
- You have an electric car and can use an overnight EV tariff for the whole home.
- You use a lot of electricity in the evening, so every kWh stored has somewhere to go.
- You want backup for power cuts, which has a value the savings figures leave out (if the installation includes backup hardware).
- You plan to add solar later, which opens up Octopus Flux and summer solar storage.
If it still adds up
A battery on its own is a simple installation: no roof work and, with a single inverter within 3.68 kW, only a notification to the network operator after commissioning. Check the installer is MCS certified for batteries, confirm the location meets the home-battery fire-safety specification, and get prices from more than one company. Compare home battery storage quotes side by side before committing. If you were hoping for a battery that plugs into a socket with no installer, the 2026 plug-in solar rules do not cover plug-in batteries.
Questions people ask
Can you have a home battery without solar panels?
Yes. Installed on its own, a battery charges from the grid when prices are low and supplies the home when they are high. HMRC's VAT Notice 708/6 covers standalone batteries, so installation carries 0% VAT until 31 March 2027.
Is a home battery worth it without solar?
Only if you can buy electricity at very different prices through the day. A back-test on the last 12 months of real Agile Octopus prices gives £239 to £266 a year from a 10 kWh battery on its own for a home using 3,000 kWh, which is a payback of 20 years or more at Octopus's published price. Homes with an electric car on an overnight EV tariff, or with high evening use, do better.
Which tariff is best for a battery without solar?
Agile Octopus is open to any smart-meter customer, and British Gas Charge Power is designed for homes that already have a battery, with or without solar. Octopus Flux needs solar, Octopus Go needs an electric car charged at home, and Cosy needs a heat pump or electric heating. Check each supplier's current terms before you rely on one.
How big a battery do I need without solar?
Enough to cover the electricity you use outside the cheap hours, and no more. In the back-test a 5 kWh battery earned about 94% of what a 10 kWh one did for a home using 3,000 kWh, and sizes above 10 kWh added nothing. At 4,500 kWh a year 13.5 kWh adds about £7, and at 6,000 kWh about £17, over 10 kWh.
Do I need an electric car for Octopus Go?
Yes. Octopus's Go page says you must have an electric car that you charge at home. Intelligent Octopus Go is for compatible cars and chargers, and neither page mentions home batteries.
Can a battery-only home use British Gas Charge Power?
Yes. British Gas says Charge Power works with all batteries, with or without solar, for customers with a smart meter sending half-hourly readings and a fixed Direct Debit. It gives half-price electricity from midnight to 5am. British Gas does not publish the unit rates on that page, so ask for a personal quote and work out a whole-year bill.
Can I sell battery electricity back to the grid without solar?
The Smart Export Guarantee is a scheme for electricity from eligible generation such as solar, and whether a supplier pays for exports from a battery charged from the grid depends on its own terms. Octopus's Outgoing tariffs are aimed at homes with solar, batteries or other ways of exporting, and its FAQ says a home can charge a battery on cheap Agile prices and export at peak times. A battery-only home should still plan on using its stored energy: at 26p to 37p a unit, using it saves more than the 12p to 16p an export tariff pays.