Home battery prices have fallen substantially, but quotes still vary wildly for what looks like the same product. Here is what you should actually be paying in 2026 and how to compare like for like.
Typical installed prices
| Usable capacity | Typical installed cost | Cost per usable kWh |
|---|---|---|
| 5 kWh | £3,500 - £5,000 | £700 - £1,000 |
| 10 kWh | £5,000 - £7,500 | £500 - £750 |
| 15 kWh | £7,000 - £10,000 | £470 - £670 |
| 20 kWh | £9,000 - £13,000 | £450 - £650 |
Larger systems are cheaper per kWh because installation labour, the hybrid inverter and the electrical work are largely fixed costs. Batteries installed alongside solar are cheaper than retrofits, because a single hybrid inverter can serve both — a retrofit often needs an additional AC-coupled inverter, adding £800-£1,500.
Domestic battery storage is currently zero-rated for VAT in the UK, whether installed with solar or on its own.
Compare usable, not nominal
The most common quoting trick is quoting nominal capacity. A "10 kWh" battery with 90% depth of discharge gives you 9 kWh. Another gives you 9.8 kWh. Always ask for the usable figure and divide the price by that.
Also compare:
- Round-trip efficiency — 88% or better. Below that you lose a meaningful slice of every stored unit.
- Continuous power output (kW) — a 3 kW battery cannot run an oven and a kettle together. 5 kW+ is more comfortable for a family home.
- Warranty — ten years, with a stated end-of-term capacity (usually 70-80%) and a throughput limit in cycles or MWh.
- Backup capability — most batteries do not power your home during an outage unless a backup gateway is specified, which costs extra.
Where the savings come from
A battery earns money two ways:
- Storing your own solar instead of exporting it. You avoid buying a unit at your import rate rather than selling it at your export rate — typically a 15-25p per kWh difference.
- Tariff arbitrage. On a time-of-use tariff, you charge overnight at a low off-peak rate and discharge during peak hours. This works with no solar at all, which is why battery-only installations have become common.
A 10 kWh battery cycling once a day, saving roughly 18p per kWh, generates around £550-£650 a year. Against a £6,000 installed cost that is a nine to eleven year payback, with warranties running to ten years and useful life typically longer.
Sizing
Look at your overnight and evening consumption, not your annual total. Most UK homes land between 5 kWh and 10 kWh of useful capacity. Oversizing is the most common expensive mistake — capacity that never cycles never earns anything.
Size up if you have an EV, a heat pump, high evening usage, or a solar array bigger than 5 kWp.
Questions to ask on every battery quote
- What is the usable capacity, not nominal?
- What is the round-trip efficiency?
- What continuous and peak power output does it deliver?
- Does the warranty state an end-of-term capacity and a throughput limit?
- Is a backup gateway included, and will it power the whole house or a single circuit?
- Which time-of-use tariffs is the system compatible with?
Get two or three quotes and compare cost per usable kWh. That single number cuts through nearly all the marketing.
Read next: Tesla Powerwall vs GivEnergy vs Sunsynk and Smart Export Guarantee rates.