5kWh battery price: what a small home battery costs fitted
Batteries under 6 kWh are the most common size recorded by MCS, and the most expensive for each kWh they hold. Here is what the official figures put them at, size by size.
Quick answer
A 5 kWh home battery costs about £6,500 fitted, on DESNZ's 2025/26 median of £1,300 per nominal kWh for batteries under 6 kWh, at 0% VAT (to 31 March 2027). From 1 April 2027 the same job would be about £6,800. Half of the installs recorded in this band cost more per kWh and half cost less.
Prices for batteries from 2 to 5.5 kWh
The table below prices the sizes most often sold in this band. The first column is our modelled price, which follows the line the calculator uses; the last column is the plain sum of size times the band's median, which you will see in some cost guides. Below about 5.1 kWh, the band's average size, the two agree. Above it the modelled price bends towards the middle band, because a 5.9 kWh battery does not suddenly cost what a pure "small battery" median says.
| Nominal size | Modelled, 0% VAT | Same job from 1 April 2027 | Size × £1,300 |
|---|---|---|---|
| 2 kWh | about £2,600 | about £2,700 | £2,600 |
| 3 kWh | about £3,900 | about £4,100 | £3,900 |
| 4 kWh | about £5,200 | about £5,500 | £5,200 |
| 5 kWh | about £6,500 | about £6,800 | £6,500 |
| 5.5 kWh | about £6,800 | about £7,200 | £7,200 |
Every figure is per nominal kWh: the capacity on the battery's label, which is what installers record with MCS and what DESNZ prices. The figures include the battery, fitting it and connecting it to the supply. They leave out solar panels, extended warranties and building work done at the same time. Want a size the table does not show? The solar battery price calculator takes any size from 1 to 30 kWh.
Why a small battery costs the most per kWh
Look at any battery quote and a large share of the work has nothing to do with how many kWh the box holds. Someone has to come out, decide where the unit can safely go, run cable to the consumer unit, fit isolation and protection, set the system up, commission it, issue the electrical certificate and tell the network operator. A 3 kWh battery needs nearly all of that. So does a 13 kWh one.
Divide those fixed costs by five kWh rather than ten and they weigh twice as heavily on the price per kWh. That is the simplest reading of why DESNZ's small band sits at £1,300 per kWh while the middle band is £890 and the large band £630. It also explains why the small band is the only one where we would treat a much lower quote with a little care: ask what has been left out before you assume you have found a bargain.
The small band was the only one to rise sharply
Between 2024/25 and 2025/26 the median for batteries under 6 kWh rose from £1,080 to £1,300 per kWh, about 20%. The mean rose less, from £1,200 to £1,280. DESNZ does not say why, and we won't guess. The other two bands moved by single figures: the middle band fell about 2% and the large band rose about 7%. The price trend guide sets out both years side by side.
Usable capacity changes the sums most at this size
Most batteries keep part of their capacity in reserve to protect the cells, so the energy you can actually draw out is often a little lower than the label. Specification sheets usually give both figures. DESNZ prices the nominal one, so a quote's price per usable kWh will sit above any official median.
The gap bites hardest on small batteries, because each missing kWh is a bigger share of the whole. Take an illustrative example: a battery sold as 5 kWh at about £6,500 that lets you use 4.5 kWh works out at roughly £1,400 per usable kWh, against £1,300 per nominal kWh. Two small batteries with the same label and the same price can therefore be quite different buys. The price per kWh page compares nominal, usable and warranted kWh side by side, and its quote checker does the division for you.
Ask for these in writing on a small-battery quote
- Nominal and usable capacity, from the manufacturer's specification sheet.
- The inverter's power rating in kW, which decides the network paperwork (see below).
- Whether the price includes any backup function for power cuts, and which circuits it covers.
- The warranty's years and its energy throughput limit, so you can work out a price per warranted kWh.
The rules that apply whatever the size
A small battery is still covered by PAS 63100, the specification for protecting homes against battery fires, sponsored by DESNZ and published by BSI. It is not law in itself, but Warm Homes: Local Grant requires it, and an installation that follows it comes with a statement of conformity attached to the electrical certificate. Its location rules don't get softer because the battery is small:
- No battery in a room where people sleep, on an escape route such as a landing or staircase, or in a cupboard that opens into a bedroom.
- No battery in a loft, roof space or void.
- Outdoors where practicable, but not within 1 m of doors, windows, escape routes or ventilation openings.
- Indoors, fire-resisting separation from the places above, fresh-air ventilation to the outside and, in a rarely visited spot such as a store cupboard, a smoke or multi-sensor alarm linked to the home's other alarms.
Each of those can add a line to the quote. The guide to what adds to a battery quote goes through them as cost items.
Small batteries and the network operator
The network paperwork depends on the inverter's power in kW, not the battery's capacity in kWh. MCS says storage over 3.68 kW needs a G99 application before installation; at or below that, a notification within 28 days of installation is usually enough. A small battery paired with a small inverter is the size most likely to stay on the simpler route. Our guide to G98 and G99 applications explains what each means for timing.
Is a small battery the right size to price?
That is a usage question more than a price one. Ofgem's typical figures for a low-use home on a single-rate meter are 1,600 kWh of electricity a year, about 4.4 kWh a day; a medium-use home is 2,500 kWh, about 6.8 kWh a day. A battery can only shift power you would otherwise buy at a higher price or export for less, so a battery much bigger than the evening and night use you want to cover adds cost without adding much.
If your use is low, or your panels are small, a battery in this band may be the size to price, even at the highest cost per kWh. If you are close to the 6 kWh line, price the next band as well: the 10 kWh battery price page shows how fast the price per kWh falls once you cross it. And if you are adding storage to panels already on the roof, start with what a battery for existing solar costs, because the retrofit route shapes the quote.
Small battery price questions
How much is a 5 kWh battery fitted?
About £6,500 at 0% VAT (to 31 March 2027), on DESNZ's 2025/26 median of £1,300 per nominal kWh for batteries under 6 kWh. Invoiced from 1 April 2027 the same job would be about £6,800.
Is a small battery poor value?
It costs more for each kWh of storage, because the fixed parts of any installation are spread over fewer kWh. Whether that matters depends on how much stored power your home can actually use each day, which is a question about your usage and tariff rather than the price table.
Can I add more capacity later?
Some systems are sold as modules that can be added to; others cannot be extended. If you might want more storage later, ask the installer in writing whether the model you are quoted can be extended, what an extra module would cost and whether the network paperwork would need redoing.
Sources (page last reviewed 3 November 2026)
- DESNZ: MCS certified domestic battery installation statistics (April 2024 to March 2026 workbook, published 28 May 2026), checked 3 November 2026.
- HMRC: VAT on energy-saving materials and heating equipment (Notice 708/6), sections 2.1, 2.3 and 2.19, checked 3 November 2026.
- BSI / DESNZ: PAS 63100:2024, battery energy storage systems in dwellings (PDF), checked 3 November 2026.
- MCS: notifying distribution network operators (G98 and G99), checked 3 November 2026.
- Ofgem: review of typical domestic consumption values, decision (May 2026; values from 1 July 2026), checked 3 November 2026.
- Which?: solar panel battery storage (secondary source, page updated 30 October 2026), checked 3 November 2026.
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