Large home battery price: what 11 to 30 kWh costs fitted
Large batteries are the cheapest per kWh and the fastest-growing size in the official figures. They are also where the storage limits, the network application and the cost of where the battery goes start to shape the quote.
Quick answer
Batteries of 11 kWh and over cost a median of £630 per nominal kWh fitted in 2025/26 (DESNZ), at 0% VAT (to 31 March 2027). That puts a 15 kWh battery at about £9,700 and a 20 kWh battery at about £12,600. From 1 April 2027 add 5% for VAT on the same pre-VAT price.
Large battery prices from 11 to 30 kWh
The table runs from the bottom of the band to the top of DESNZ's range. Up to the band's average size the price follows the line between the official anchor points. Beyond about 15.5 kWh it is simply size times the £630 median, because the statistics give no evidence that the price per kWh keeps falling.
| Nominal size | 0% VAT (to 31 March 2027) | 5% VAT (from 1 April 2027) | Enclosures at most 20 kWh each |
|---|---|---|---|
| 11 kWh | about £8,900 | about £9,400 | one can be enough |
| 12 kWh | about £9,100 | about £9,600 | one can be enough |
| 13.5 kWh | about £9,400 | about £9,900 | one can be enough |
| 15 kWh | about £9,700 | about £10,200 | one can be enough |
| 16 kWh | about £10,100 | about £10,600 | one can be enough |
| 18 kWh | about £11,300 | about £11,900 | one can be enough |
| 20 kWh | about £12,600 | about £13,200 | one can be enough |
| 25 kWh | about £15,800 | about £16,500 | two or more |
| 30 kWh | about £18,900 | about £19,800 | two or more |
The band that more than doubled
In 2024/25 DESNZ's sample held 4,926 batteries of 11 kWh and over, 20.6% of the total. In 2025/26 it held 12,176, 28.4%. No other band grew as fast. Over the same year the median price per kWh rose from £590 to £630, about 7%, and the mean from £660 to £670.
Here the mean sits above the median, the opposite of the middle band. That pattern usually points to a tail of dearer installs rather than cheap ones: in a band that runs all the way to 30 kWh, a minority of large, multi-unit systems with backup and extra protection would do it. Again, DESNZ doesn't publish the spread, so treat this as a reading of two numbers, nothing more.
What it means for a quote is practical. At this size the battery itself is a bigger share of the bill than in the small band, so the price per kWh is lower, but the quote is more likely to carry the extra items below. Compare like with like: the quote checker sets any total against £630 per kWh, and the extras page explains each line you might see.
Storage limits that shape a large-battery quote
PAS 63100, the BSI specification for protecting homes against battery fires, sets limits that only matter once a battery gets big:
| Where the batteries are | Most energy per home |
|---|---|
| Outdoors, in a detached garage or outbuilding, or in an attached garage with fire-resisting separation (REI 60) | 80 kWh |
| Anywhere else in the home | 40 kWh |
| In any single enclosure | 20 kWh |
So a 25 kWh system needs at least two enclosures, and two enclosures need two suitable spots, each meeting the location rules: no bedrooms, escape routes, lofts or voids, nothing outdoors within 1 m of a door, window or vent. In a garage or beside a driveway the units need protection against impact (IK10). None of these come with an official price; all of them can show up on a quote.
PAS 63100 also covers homes up to 200 m² of floor area. For a bigger home the specification does not apply as written, which is worth raising with any installer quoting for a very large property.
The network application on a big battery
What decides the network paperwork is the power of the inverter in kW, not the battery's capacity in kWh. MCS says storage over 3.68 kW must be applied for under G99 before installation, while smaller systems can usually be notified under G98 within 28 days. A large battery may be paired with a larger inverter, and with solar on the same connection the total is likely to be above the G98 limit of 16 A per phase. The G99 route means waiting for the network operator's answer before the work starts, and the answer can come with conditions.
Ask your installer which form they will submit, who submits it and how long they expect it to take. The network application guide sets out both routes.
Which homes use a large battery's capacity
Ofgem's typical consumption values give a sense of scale. A high-use home on a multi-rate meter uses about 6,100 kWh a year, roughly 16.7 kWh a day; a high-use home on a single-rate meter about 3,800 kWh, roughly 10.4 kWh a day. A large battery only earns its place if a meaningful share of that daily use falls outside the cheap or sunny hours and the battery can be filled to cover it. For a medium-use home, at 2,500 kWh a year on a single-rate meter, much of a 15 or 20 kWh battery may sit unused for much of the year.
Does bigger mean better value?
Only if you use it. The price per kWh is lowest in this band, but every kWh still costs around £630. A battery that fills on a summer afternoon may not fill in December, and one that is never emptied is storage you paid for and didn't use. Our 10 kWh battery price page covers the size most homes stop at; the year-one bill effect guide lets you test a size against your own tariff.
Large battery price questions
How much does a 15 kWh home battery cost?
About £9,700 fitted at 0% VAT (to 31 March 2027), modelled from DESNZ's 2025/26 figures, where the median for batteries of 11 kWh and over was £630 per nominal kWh. From 1 April 2027 the same job would be about £10,200.
Is there a limit on how much battery a home can have?
Under PAS 63100, the fire-protection specification for home batteries, one enclosure holds no more than 20 kWh, and a home holds no more than 40 kWh in most locations. The limit is 80 kWh where the batteries are outdoors, in a detached garage or outbuilding, or in an attached garage with fire-resisting separation.
Why does the price per kWh stop falling above about 15 kWh on this site?
Because the official data stops telling us. DESNZ gives one median for everything from 11 to just under 30 kWh, and the band's average battery was about 15.5 kWh. Above that size the price is kept at £630 per kWh rather than inventing a further fall.
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.
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