Home batteries: what they cost, how much they store and when they pay back
A battery does not generate anything. It moves electricity from a cheap hour to an expensive one, so the saving comes from the gap between those prices — which means your tariff matters more than the hardware.
We'll tell you whether it suits your property before anyone tries to sell you one.
Installed cost
£3,500–£8,000
Around 5–10 kWh usable, including the inverter and fitting
Usable capacity
80–95% of nominal
Batteries are sold on nominal kWh; you cannot use all of it
Warranty
10 years
Typically 6,000–10,000 cycles or a throughput limit, whichever comes first
Annual bill saving
£150–£600
Almost entirely determined by the tariff you are on
Illustrative. Placeholder figures to show what this page will hold. Real ranges arrive with the quote and performance data behind them.
The short answer
A battery earns its keep on a time-of-use tariff with a cheap overnight window, shifting your evening use off the peak rate. On a single flat rate with no solar there is almost nothing for it to capture, and the payback outlives the warranty.
We don't sell home batteries, and no installer pays to appear here. If the answer for your home is no, the page will say so.
Usually worth it if
- Time-of-use tariff with a cheap overnight window
- Solar already fitted and mostly exported in summer
- High evening use from an EV or heat pump
Probably not yet if
- Flat-rate tariff with no solar and no EV
- Loft the only space left for the cabinet
- Insulation and draught-proofing still undone
Costs
What it costs
Cost per kilowatt hour falls as the battery gets bigger, because the inverter, the electrical work and the day's labour are much the same either way. Retrofitting to an existing solar system can mean a second inverter or replacing the one you have. These are the bands we will publish once real quote data is in.
5 kWh, retrofitted to existing solar
Installed cost
£3,000–£5,000
- Annual bill saving
- £150–£350
- Payback
- 12–22 years
10 kWh, off-peak charging, no solar
Installed cost
£4,500–£7,500
- Annual bill saving
- £250–£500
- Payback
- 12–20 years
10 kWh fitted alongside a new solar system
Installed cost
£4,000–£7,000
- Annual bill saving
- £300–£600
- Payback
- 10–18 years
15 kWh or more, large home with an EV or heat pump
Installed cost
£7,000–£12,000
- Annual bill saving
- £400–£900
- Payback
- 10–18 years
Illustrative. Placeholder figures to show what this page will hold. Real ranges arrive with the quote and performance data behind them.
The homes
What the certificates say about home batteries
Every energy certificate in England and Wales records what the assessor found and lists what would raise the rating. Counted up, they show how many homes are still waiting for this.
Certificates recommending one
Under 0.1%
Of homes; only certificates from 2025 on suggest it
Solar on the certificate
1.6%
A battery earns most beside panels
| Measure | Recommended to | The EPC method's cost |
|---|---|---|
| Battery | Under 0.1% of homes | £500–£5,000 |
| Solar panels | 66.4% of homes | £8,000–£10,000 |
From the EPC register to 9 September 2026, each home's latest certificate, England and Wales. A certificate recommends what would raise its rating, by the rules of the year it was lodged. The method's cost is the range the middle recommendation was given, the same for every home: a guide, not a quote.
Grants
What you can claim, nation by nation
Batteries get far less public support than heating measures. The zero VAT rate is the main one, and it now covers batteries fitted on their own as well as those installed with solar. The relief is time-limited, so we will publish the current end date alongside the date we checked it.
England and Wales
- 0% VAT on battery storage
- Smart Export Guarantee
- ECO4
There is no grant aimed at home batteries. The saving comes from a time-of-use tariff, and in some cases from exporting stored electricity under the Smart Export Guarantee — though several suppliers restrict export payments for units that came off the grid rather than the roof. ECO4 may fund storage as part of a wider package for eligible households.
Scotland
- Home Energy Scotland loan
- 0% VAT on battery storage
- Smart Export Guarantee
Home Energy Scotland offers an interest-free loan towards battery storage, usually when it is installed with renewables, with an uplift for eligible rural postcodes. We will publish the current limits and conditions with their source date.
Northern Ireland
- 0% VAT on battery storage
- NI Sustainable Energy Programme
The zero VAT rate applies, but the Smart Export Guarantee does not cover Northern Ireland and there are fewer time-of-use tariffs to arbitrage. Both of those weaken the case for a battery here, so the payback needs checking against what your own supplier actually offers.
Scheme rules change. Each one will carry the date we last checked it against Ofgem and GOV.UK.
Your property
Will it suit your home?
The answer turns on how your home was built, not on what the product can do in a brochure.
Your tariff does the work
A battery only pays if you can buy electricity cheaply at some hours and avoid buying it at others. Time-of-use tariffs with a cheap overnight window are where almost all of the saving comes from; on a single flat rate with no solar, there is very little to capture.
Sizing against what you use
The useful size is roughly the electricity you get through between the end of the cheap window and the start of the next one. Oversizing adds cost that never cycles; undersizing means paying peak rates for the last few hours of the evening.
With solar, or without
Adding storage to an existing solar system can be AC coupled, which bolts on beside the current inverter and works with any brand, or DC coupled through a replacement hybrid inverter, which is slightly more efficient but a bigger job. New installations usually go DC coupled from the start.
Where it goes
A garage, utility room or an outdoor rated cabinet all work. Lofts are a poor choice: the weight needs checking and the temperature swings shorten the life of the cells. Somewhere cool, dry and close to the consumer unit keeps both the cable run and the cost down.
Fire safety and siting
Lithium batteries are regulated products and installation is notifiable electrical work. Industry guidance keeps them out of escape routes, loft spaces and habitable rooms where it can, and asks for separation from anything flammable. Ask the installer which standard they are working to and see it written into the quote.
Backup during a power cut
Most batteries will not keep the lights on by default. Supplying the house when the grid is down needs a changeover switch or a backup gateway and a separate protected circuit, fitted at extra cost. If that is why you want a battery, say so before the quote is written.
In progress
What lands on this page next
Some of this page is built from published data now. Still to come, in order:
- Battery sizing based on your own half-hourly consumption, not a household average
- Cost bands from real quotes, by usable capacity and whether solar is already fitted
- A saving estimate for each time-of-use tariff you could actually switch to
- Which export tariffs pay for stored electricity and which only pay for solar
- How storage changes the case for solar, an EV charger or a heat pump on the same home
Where the answers come from
- Smart meter half-hourly data — when your household actually uses electricity
- Supplier tariff data — off-peak rates, peak rates and export terms
- EPC Register — property type, heating and any existing solar
Questions
Common questions
Will a battery keep my lights on in a power cut?
Usually not, unless it was specified that way. A standard installation shuts down with the grid for safety. Backup needs extra equipment and wiring, and most systems only protect a few chosen circuits rather than the whole house.
Do I need solar panels to have a battery?
No. A battery can charge from the grid during a cheap off-peak window and discharge through the expensive evening rate. Solar gives it a second source of cheap electricity and lifts the number of useful cycles, but it is not a requirement.
What is the difference between nominal and usable capacity?
Nominal is the total the cells hold; usable is what the system will actually let you take out, because some is held back to protect the battery's life. Quotes should state the usable figure, and it is the one to compare between products.
How long will a battery last?
Warranties typically run to ten years and are capped by cycles or by total energy throughput, with a guaranteed remaining capacity at the end — often around 70 to 80% of the original. A battery cycled hard every day on a time-of-use tariff reaches that limit sooner than one that mostly soaks up summer solar.
Can I add a battery to solar panels I already have?
Yes. An AC coupled battery works alongside your existing inverter whatever its make, and is the usual retrofit. Replacing the inverter with a hybrid one is tidier and a little more efficient, but only worth it if the original is near the end of its life anyway.
Do I get paid for exporting from the battery?
Sometimes. Export tariffs in Great Britain are set by each supplier and some pay only for generation from the panels, not for stored grid electricity sold back at peak. Northern Ireland is outside the Smart Export Guarantee altogether. Check the terms before you count that income.
See whether home batteries suit your home
Start with your postcode and we'll work from what is already known about the property.