The honest answer to "what does a home battery cost" is that it depends far more on size than on brand, and that the price per kWh falls sharply as the battery gets bigger.
Here is what the market actually charges, using government data from real MCS-certified installations rather than anyone's advertising.
The benchmark nobody quotes
DESNZ publishes median installed costs from MCS-certified battery installations. For April 2024 to March 2025, across 22,398 systems:
| System size | Median cost per kWh |
|---|---|
| Under 6 kWh | £1,020 |
| 6 – 11 kWh | £900 |
| 11 – 30 kWh | £590 |
That is the real market, not a brochure. And it tells you something important: a small battery is a bad deal per unit of storage. The scaffold, the electrician, the inverter, the isolators, the DNO application and the certification cost roughly the same whether you fit 5 kWh or 15 kWh. Only the cells scale.
What that means by size
5 kWh — roughly £4,500 to £5,500 installed. The worst value per kWh on the list. It will cover an evening of lights, fridge, router and television, but it will be empty most winter mornings and it will not take a full day of summer generation. We fit them where space or budget genuinely dictates, and we say plainly that 10 kWh is better value.
10 kWh — roughly £7,500 to £9,000 installed. The median on DESNZ data lands close to £8,900. This is the sweet spot for most three and four bedroom houses: enough to hold a decent summer day's surplus, enough to shift a full overnight cheap-rate charge, and enough to run essential circuits for a couple of days in an outage if backup is fitted.
15 kWh — roughly £9,000 to £12,000 installed. Here the per-kWh cost drops into the £590 to £700 band. Worth it if you have an EV charging at home, electric heating, a heat pump, or a large array producing more than 10 kWh can absorb on a June afternoon.
20 kWh and above — from roughly £12,000. Genuinely economic per kWh, but only if you have the consumption to justify it. A battery that never gets below 60% is money sitting on a wall.
Prices exclude VAT where applicable — domestic installations are 0% VAT until 31 March 2027, then 5%. On a £9,000 system, installing after that date costs £450 more.
Why the hardware cost and the installed cost look so different
Worth being transparent about, because it comes up.
Battery modules at published trade prices in late 2026 run roughly £130 to £280 per kWh depending on module size — the larger the module, the cheaper per kWh. A 10 kWh stack might be £2,000 to £2,400 of cells.
So on a £8,900 installed median, the cells are a quarter of it. The rest is the hybrid inverter, the backup gateway if fitted, isolators and protective devices, cable, labour across one or two days, scaffolding where needed, the DNO application, MCS certification and documentation, insurance-backed warranty, and margin.
Anyone selling at half the market rate is cutting one of those, and it is usually the certification, the protection or the margin that keeps the company alive long enough to honour your warranty.
What actually moves your price
- Where the battery goes. A garage wall next to the consumer unit is cheap. A loft, a cupboard at the other end of the house, or an outbuilding adds cable, labour and sometimes a day.
- Whether you need a new inverter. Retrofitting to existing solar can mean an AC-coupled inverter alongside what you have, or replacing the string inverter with a hybrid. The second is tidier and more expensive.
- Backup. A single EPS output is cheap to include at installation. Whole-home backup needs a gateway and usually a second consumer unit for the backed-up circuits. Done at the time it is a few hundred pounds of kit plus labour; done later it is substantially more.
- Your supply. Older properties with 60A or 80A fuses may need load management or a DNO fuse upgrade.
- DNO approval. Most domestic batteries need a G99 application before installation, and the timescale is weeks, not days.
Is it worth it?
Depends entirely on your tariff and your usage, and we would rather tell you no than sell you something that does not pay.
A battery earns money three ways: storing your own surplus solar instead of exporting it at a low rate, charging overnight on a cheap tariff and discharging at peak, and exporting at peak on a time-of-use export tariff. The second of those works without solar at all, which is why battery-only installations have become common.
What makes it pay: a cheap overnight rate, high daytime consumption, and a peak export tariff. What makes it marginal: a flat tariff, low consumption, and an undersized battery.
Send us twelve months of consumption figures and we will model it honestly, including the case where the answer is that a battery will not pay for itself at your usage.
A word on warranties
Battery warranties are less straightforward than they look, and two things are worth checking on any quote you receive.
Headline terms are often conditional. Several manufacturers advertise a 12-year warranty where the standard term is five years, extended only if the system is registered to the manufacturer's cloud platform within a set window and stays connected. If your monitoring goes offline for months, you can lose the extension. Ask which figure you are being quoted and what the conditions are.
Warranties usually cap throughput as well as time. Cover typically runs until the battery drops below 70% of its rated energy, or until a stated total MWh has passed through it, whichever comes first. For a heavily cycled battery on a daily arbitrage strategy, the throughput cap can arrive first.
We will tell you both figures for whatever we quote, and whether the warranty runs to you or to us as the installer.
Get a real number
We install battery storage across Milton Keynes, Buckinghamshire, Bedfordshire, Oxfordshire and Northamptonshire, with or without solar, and with or without backup.
Tell us your house, your tariff and roughly what you use, and we will give you a figure with the components named — not a range designed to get us through the door.