How much does a solar battery cost in the UK?

A home battery fitted by an installer costs roughly £4,100 for 5 kWh and £5,100 for 10 kWh when it is added to a house on its own, and about £900 less when it goes in at the same time as new solar panels, because one hybrid inverter can then run both. These are our estimates, fitted to installed prices published by Octopus Energy (Octopus page, read 23 September 2026), MoneySavingExpert (updated August 2026) and Sunsave (updated July 2026). They include installation and VAT, which is currently 0% on batteries fitted in homes.

Bigger batteries cost less per kWh of storage, but only pay off if your home can use the extra energy. How much a battery saves depends mainly on your tariff, especially whether it lets you charge cheaply overnight, and when you use electricity; the worked examples below show the arithmetic. For how batteries work and how to size one, see our solar battery storage guide.

Solar battery prices by capacity

Battery capacity is measured in kWh, the amount of energy it can store. It is different from its power in kW, which is how much it can supply at once: a battery rated at 5 kW can run more appliances at the same time than one rated at 3 kW, whatever their capacity.

How the table is worked out: a battery added on its own is estimated at £3,100 plus £200 per kWh, so 10 kWh is £3,100 + (10 × £200) = £5,100, or £510 per kWh. Fitted with new panels, the battery shares the solar system's hybrid inverter, which our calculator already prices at about £900, so the add-on is £2,200 plus £200 per kWh: £2,200 + (10 × £200) = £4,200.

The fixed part explains why the price per kWh falls so steeply. The inverter, the installer's time, commissioning and paperwork cost about the same whatever the capacity, so doubling from 5 to 10 kWh adds about £1,000 rather than doubling the price.

What installers and suppliers publish

These are the published prices the estimate is built on, with their dates:

Octopus says battery installation is subject to approval from your network operator. It also lists a package of twelve 455 W panels with a 10 kWh battery for £11,115, based on its April 2026 prices. Prices for the Tesla Powerwall 3 are covered in our Powerwall 3 price guide.

Why a battery is cheaper with new panels

When you buy panels and a battery together, the installer can fit one hybrid inverter that manages both, with one visit, one scaffold and one set of paperwork. That is the main reason for the roughly £900 difference in our table. MoneySavingExpert makes the same point: a battery is "much cheaper when bought with solar panels".

Adding a battery to an existing solar system means either replacing the solar inverter with a hybrid one, or fitting an AC-coupled battery with its own inverter, connected to your home's wiring next to the solar inverter. The second route brings a network rule into play. Under the G98 procedure, an installer can connect generation of up to 16 A per phase (3.68 kW on a normal single-phase supply) and notify the network operator afterwards. The limit counts the combined output of every inverter, including the battery's. MCS gives the example of a 3 kW solar system and a 3 kW battery on the same single-phase supply: together they exceed 16 A, so the G99 procedure applies and the network operator must approve the connection before it is switched on. Ask the installer whether your battery needs a G99 application and whether the quote includes it.

What changes the price of a battery

• Usable capacity. Quotes may give nominal (total) or usable capacity. MCS's method uses usable capacity and, where a datasheet gives only nominal capacity, assumes 90% is usable for most battery types. A "5.12 kWh" battery at 90% gives about 4.6 kWh you can use. Compare prices per usable kWh.
• Power in kW. A higher continuous power lets the battery cover more of the evening peak at once.
• Backup in a power cut. A battery does not automatically keep your lights on in a power cut. Backup needs extra hardware to isolate the house from the grid, and a quote should say which circuits stay on.
• Warranty. Octopus lists battery warranties of 10 to 15 years depending on the model. Check the years, the capacity the maker guarantees at the end, any limit on energy throughput, and who handles claims in the UK.
• Compatibility. The battery must work with your inverter and, if you want a smart tariff, with the supplier's control system. Check both before you sign.

VAT on solar batteries

Batteries installed in homes have had 0% VAT since 1 February 2024. HMRC's guidance says this covers a battery retrofitted to existing solar panels, a standalone battery that stores electricity from the grid, and a battery that stores both. The zero rate runs until 31 March 2027; from 1 April 2027 it is due to return to 5%, not 20%, unless the government extends it.

The relief applies only when the battery is installed. A battery bought without installation is charged the standard 20% rate.

Is a solar battery worth the cost?

A battery saves money in two ways: it stores your own solar electricity for the evening, and it can store cheap electricity to use when grid electricity is expensive. On each kWh it delivers, the saving is the price you would have paid for grid electricity minus what the stored energy cost you: the export payment you gave up, or the cheap-rate electricity you bought. Some energy is lost when a battery charges and discharges; we assume 90% comes back out.

Storing solar electricity. At the Ofgem price cap average for October to December 2026 (26.32p per kWh, no VAT), each kWh the battery delivers from your panels saves:

• 12.99p if you would otherwise export at 12p with Octopus Outgoing, which needs Octopus as your electricity supplier on a compatible tariff: 26.32p − (12p ÷ 0.9) = 12.99p;
• 19.65p if you keep your supplier and export at 6p with E.ON Next's Flex Export, which is open to customers of other suppliers (rate on 23 September 2026): 26.32p − (6p ÷ 0.9) = 19.65p.

A better export rate makes the battery worth less, because each kWh you store is a kWh you did not sell.

Worked example (illustration, not a forecast). A household uses 2,500 kWh a year (Ofgem's typical medium use) and has a 4 kWp south-facing system at 35° in Birmingham, producing about 3,872 kWh a year (4 × 968 kWh per kWp, from the EU's PVGIS tool). MCS's self-consumption tables, which installers use for their performance estimates, give the share of that solar electricity used at home with and without a battery, for each occupancy pattern. For a home that is out for half the day, a 5 kWh battery (4.5 to 4.6 kWh usable, depending on the model) raises it from 19% to 52%. That is (52% − 19%) × 3,872 = 1,278 kWh a year used at home instead of exported, worth 1,278 × £0.2632 = £336. Charging the battery for it takes 1,278 ÷ 0.9 = 1,420 kWh of export given up, worth £170 at 12p. The net saving is £166 a year, so a £3,200 battery fitted with the panels pays back in about 19 years at today's prices. Keeping your supplier and exporting at 6p instead gives £251 a year and about 13 years; with import prices rising 2% a year (the Bank of England's inflation target, used as an assumption, not a forecast) and export staying at 12p, payback falls to about 15 years. Added later on its own at £4,100, the same battery takes about 25 years at 12p and today's prices.

The tables apply the same method to each MCS occupancy pattern:

Assumptions: first-year self-consumption from MCS guidance MGD 003; import price 26.32p per kWh (Ofgem cap, October to December 2026); export at 12p (Octopus Outgoing, needs Octopus as your electricity supplier on a compatible tariff) or 6p (E.ON Next Flex Export); prices held flat except in the last column, where only the import price rises 2% a year; 90% round-trip efficiency; battery used for solar only, with no grid charging; no degradation, replacement or maintenance. Homes out during the day gain slightly more because more of their solar electricity is surplus.

Compare the payback with the warranty. If a battery takes 15 to 20 years to pay back on solar alone and its warranty is 10 to 15 years, you are relying on it lasting beyond the warranty, which is why the tariff it runs on matters. These figures are for the battery on its own; whether solar panels pay back is a separate question, covered in our guide to solar panel cost and the calculator below.

On a time-of-use tariff. Cheap overnight charging can add to what a battery saves, mostly in winter, when there is little solar surplus. On 23 September 2026, Octopus Flux in the London region charged 14.56p per kWh from 02:00 to 05:00, 33.96p from 16:00 to 19:00 and 24.25p at other times, before VAT; household electricity in Great Britain carries no VAT from 1 October 2026 to 31 March 2027. With 90% round-trip efficiency, a kWh charged overnight costs 14.56p ÷ 0.9 = 16.18p when it comes out, saving 17.78p against the peak rate and 8.08p against the day rate.

As an illustration, suppose that from November to February (120 days) a 5 kWh battery with 4.6 kWh usable capacity is filled once a night in the cheap window and emptied during the day. It delivers 120 × 4.6 = 552 kWh, which takes 552 ÷ 0.9 = 613 kWh to charge, costing 613 × £0.1456 = £89. If all of it replaces electricity at the day rate (552 × £0.2425 = £134), the saving is £45 over the four months; if all of it replaces peak-rate electricity (552 × £0.3396 = £187), it is £98. Most homes fall between the two, depending on how much they use between 16:00 and 19:00.

Flux needs solar panels, a battery, and both import and export with Octopus. Intelligent Octopus Flux is currently closed to new customers unless they bought their solar panels and battery from Octopus. Rates differ by region and change, so check them on the day; our guide to solar battery tariffs compares the options. Charging from the grid uses capacity that would otherwise store solar energy, so the winter tariff saving and the solar saving do not simply add up. MCS's guidance says the reduced solar benefit of using other operating modes should be worked out and explained, so ask your installer to show both for the tariff you plan to use.

Paying for a battery

• The Warm Homes Loan Scheme is designed to let approved private lenders offer cheaper loans of up to £15,000 for a battery (and up to £15,000 for solar panels), fitted by an MCS-certified installer, with a government grant to the lender reducing the rate. Lenders set their own rates and credit checks. The consumer launch phase is due from September 2026; on 23 September 2026 the government had not named any approved lender.
• In Scotland, Home Energy Scotland's grant and loan does not currently fund batteries or solar PV on their own.
• If you borrow, compare the total amount payable, including interest, with the cash price, and put that total into the payback sum.

If your installer is a member of the RECC consumer code, a deposit must never exceed 25% of the price. MCS no longer requires installers to join a consumer code, so check membership on the code's own website.

What should a battery quote include?

Use this list on every quote, and ask for anything missing in writing.

• Battery model and capacity. Brand, model, nominal and usable kWh, and the datasheet.
• Power. Continuous charge and discharge power in kW.
• Inverter. Whether it uses your existing inverter, a new hybrid inverter, or its own battery inverter, with the model.
• Network operator. Whether the total inverter output goes above 3.68 kW single-phase, and whether a G99 application is included.
• Backup. Whether the system keeps any circuits on in a power cut, and which ones.
• Tariff control. Which smart tariffs and apps the battery works with.
• Warranty. Years, end-of-warranty capacity, throughput limits and the UK contact for claims.
• Price and VAT. Total installed price, VAT rate, deposit and payment stages.

Model a battery for your home

The calculator lets you add a battery to a solar system for your address and see the change in cost and in the share of solar electricity you use yourself. It uses the same battery prices as this page and lets you choose a single-rate, overnight or import-export time-of-use tariff. The result is an estimate, not a quote.

Thinking of a battery without panels? Our guide to a home battery without solar explains when grid charging alone can work. Export rates that affect the battery sums are compared in best export tariffs.

Frequently asked questions

How much does a 10 kWh solar battery cost?

About £5,100 installed on its own, or about £4,200 when fitted with new solar panels, on our estimate. Octopus Energy's battery-only prices started at £5,336 for 10 kWh (Octopus page, read 23 September 2026).

Is a battery cheaper if I buy it with solar panels?

Usually, yes. One hybrid inverter, one visit and one set of paperwork cover both, which is worth about £900 in our estimate. If you might add a battery later, ask for a battery-ready hybrid inverter now.

How long does a solar battery last?

Plan around the warranty, which Octopus lists at 10 to 15 years depending on the model. Check how much capacity the maker guarantees at the end of it, and compare that with your payback period.

Does a solar battery pay for itself?

Slowly, if it only stores solar power on a standard tariff. In our example, a 5 kWh battery fitted with new panels saves about £166 a year and takes about 19 years to pay back with 12p export (which needs Octopus as your electricity supplier on a compatible tariff), or about 13 years if you keep your supplier and export at 6p. A time-of-use tariff that lets it charge cheaply overnight improves the sums.