Solar Battery Cost in 2026: Alone, With Panels and in a London Home

Solar battery cost by size in 2026

Prices for a battery of the same size differ by hundreds of pounds between publishers. So the table shows each figure with its source and date. All are installed prices for a home. They are published market figures, not Craftex quotes.

The price rises with capacity, but not in a straight line. In these figures a larger battery costs less per kWh, because the inverter, wiring and labour are paid once. Compare quotes on usable kWh, not the number on the label.

Cost of solar panels and a battery together

Fitted together, panels and a battery share one scaffold, one electrical visit and one notification to the network operator. Sunsave, an installer, publishes London prices for three sizes of system, with and without a 10 kWh battery.

Source: Sunsave, Solar panels in London, updated 27 July 2026, 450 W panels. In every row the battery adds £4,000. iHeat (21 May 2026) puts a combined system at £10,000 to £16,000.

What the government data says

Government data points the same way. The Department for Energy Security and Net Zero (DESNZ) publishes what certified installations actually cost, from the Microgeneration Certification Scheme database. Its figures cover panels only and include VAT where it applied.

At the 4 to 10 kW median, a 5 kW system comes to about £8,500. A 6 kW system comes to about £10,200, before any battery. That is our arithmetic on DESNZ's median, not a quote.

London installations cost 4% to 8% more per kW than the Great Britain mean in 2025/26. For 0 to 4 kW systems the London mean was £2,177 against £2,008.

If you have no panels yet, price both at once. If you already have them, a battery on its own qualifies for 0% VAT too. Either way, home battery storage is sized from one electricity bill, not from a brochure.

What adds to the cost in a London house

Published prices describe a standard roof and a standard supply. A London house often has neither. These are the lines that move a quote, in the order we check them at survey. The price guides do not price them, and we price them only from a survey.

1. Scaffold and access. A tall terrace, or a street with no room for a platform, lifts the scaffold line. If scaffold is already going up for roof work, the panels can share it.
2. Roof shape and condition. Parapets, valley gutters and hips make panels harder to fix. Old or slipped slate needs repair first. A roofer prices that before the array is laid out.
3. The consumer unit. An older fuse board may need replacing before a battery is connected. Check its age and condition at survey, not after the install date is booked.
4. The battery's place. The cheap battery is the one with a safe, legal place to sit. A longer cable run, ventilation, fire separation and a linked smoke alarm all add cost.
5. Listed or conservation status. A listed house needs listed building consent. A conservation area limits where panels may go. Both can change the layout and the programme.
6. The network operator. Above 16 A (3.68 kW) per phase, the operator must approve the connection first. Below it, your installer notifies the operator within 28 days of commissioning.

Planning permission for panels

Panels on a house roof are usually permitted development, within limits. On a pitched roof they may stand no more than 0.2 m from the slope and not above the highest point. In a conservation area they may not go on a wall that fronts a highway.

A flat roof in a conservation area needs the council's prior approval first. Listed houses lose permitted development altogether. Some boroughs have also removed these rights with an Article 4 direction.

Where a home battery can go

The best place for a battery is outside the house and away from habitable rooms. That is the starting point of PAS 63100:2024, the fire-safety specification for home batteries, sponsored by the Department for Energy Security and Net Zero. It guides installers. It is not an Act of Parliament.

The PAS does not allow a battery in any of these places:

• A room where people sleep
• A landing, staircase or corridor on an escape route
• A storage cupboard that opens into a bedroom
• A loft, roof space or void
• A cellar or basement with no way out to the outside
• Within 2 m of stored flammable materials or fuel

Outdoors, a battery must stay at least 1 m from doors, windows, escape routes and ventilation openings. Indoors, it needs fresh air vented to the outside and 30 minutes of fire-resisting separation from those rooms. Where the space is rarely visited, a smoke or heat detector must be linked to the house alarm.

In a London house, a garage, utility room, rear plant room, outbuilding or outside wall usually passes. A loft, a landing cupboard and a basement with no outside access do not. That reading is ours, not the PAS's. Wall-mounted units outside may need planning consent or building control notification.

The PAS excludes dwellings over 200 m². For a larger prime house, it says to consult a fire safety expert.

Solar battery payback: when it pays

A battery pays by moving power from when it is cheap to when it is dear. With panels, it stores midday output for the evening. Without panels, it charges on a cheap overnight tariff. An electric car or a heat pump gives it more to move.

To test a quote, divide the installed price by the yearly saving. A £6,000 battery that saves £500 a year takes 12 years. One that saves £300 takes 20. Those are round numbers to show the sum, not a forecast.

Published paybacks disagree. iHeat says 10 to 15 years for many households. The Eco Experts works out roughly 26 years for panels plus a battery. Both depend on how much of your power the battery shifts, which is why the size comes from your bills.

Battery life matters to the sum. iHeat says most last 10 to 15 years. Many manufacturers warrant them for 10 years or a set number of cycles. Read the warranty wording before you rely on it.

VAT on solar batteries and the 2027 deadline

HMRC zero-rates the installation of energy-saving materials in a home from 1 May 2023 to 31 March 2027. Solar panels were covered from the start. Batteries were added from 1 February 2024. A battery fitted to existing panels qualifies, and so does a stand-alone battery.

From 1 April 2027 the rate reverts to 5%. On an £8,000 battery job that is £400. A battery supplied without installation is standard-rated, so buy it as part of an installation. Ask for the VAT rate in writing on the quote.

Gather these before you ask for a quote. They let a firm size the battery and price the roof without a second visit.

Ready to price yours? Get a free solar and battery plan. Send a recent bill, your address and a photo of the roof. We return a panel layout, a battery size, the planning route and an indicative cost, at no charge. A survey follows before any fixed figure.

We focus on prime and period London houses: whole-home systems under one contract, or a system of any size fitted during a Craftex renovation.