A 5kWh home battery costs from £3,947 installed in Octopus's published battery-only price (a Fox ESS EVO 5 or an Enphase IQ Battery 5P, April 2026); E.ON Next sells a Sunsynk Elite from £3,995 and EDF a Sunsynk battery from £3,995 with an inverter. The official median for batteries under 6 kWh fitted in 2025/26 was £1,300 per kWh, or about £6,500 for 5 kWh. In this site's model it saves about £174 a year with 4 kWp of solar on Octopus Flux in London, or about £202 a year on Agile Octopus with no solar.
Who a 5kWh battery suits
- Smaller homes and lower users. If your bill shows under about 2,500 kWh a year, your evening use is usually small enough for 5 kWh to cover it most days.
- Small solar arrays. A 2 to 3 kWp array rarely makes enough surplus to fill a big battery outside summer.
- Starter systems. Modular batteries let you begin with one module and add more when an electric car or heat pump arrives.
- Homes with limited space. A single 5 kWh unit is easier to site within the fire-safety location rules, which rule out bedrooms, hallways and lofts, and favour outside walls or garages.
5kWh batteries compared
The products sold as “5 kWh” range from 4.6 to 5.84 kWh of usable energy. That is a 27% spread between batteries most quotes describe the same way.
| Battery | Usable capacity | Warranty | Notes |
|---|---|---|---|
| Sigenergy SigenStor BAT 6.0 | 5.84 kWh (6.02 kWh total) | 10 years at 60%, or 20.44 MWh (European terms, May 2025) | Stacks one to six modules per controller; IP66; 62 kg |
| Enphase IQ Battery 5P | 5.0 kWh | 15 years or 6,000 cycles at 60% | AC coupled, 3.2 kVA, IP55; from £3,947 installed (Octopus) |
| Fox ESS EVO 5 | 5.12 kWh nominal | 12 years at 70%, or 23.99 MWh | Battery with built-in hybrid inverter; from £3,947 installed (Octopus) |
| Fox ESS EP5 | 5.18 kWh nominal | 10 years at 70%, or 19.42 MWh | Module for a separate Fox inverter; in Octopus’s solar package from £7,915 with 4 panels |
| Sunsynk G5.3 | 4.79 kWh (5.32 kWh total) | Cells 10 years or 6,000 cycles; BMS 5 years | IP20, so indoor only; 44 kg; up to 32 in parallel |
| Sunsynk Elite | 4.6 kWh (5.12 kWh total) | Cells 10 years or 6,000 cycles; BMS 5 years | Integrated heating; one to six modules per stack; from £3,995 (E.ON Next) |
| myenergi libbi 5 kWh module | 4.6 kWh (5.12 kWh total) | 10 years, unlimited cycles when run by myenergi’s controller | IP65; 54 kg; with a 3.68 kW or 5 kW hybrid inverter |
From manufacturers’ datasheets and warranty documents, and prices published by Octopus (April 2026 prices) and E.ON Next (read 6 October 2026). Sunsynk’s warranty terms exclude “degradation General cell life”, so they set no minimum capacity.
Two points stand out. The cheapest published installed price, £3,947 at Octopus, buys 5.0 kWh usable with an Enphase unit, about £789 per usable kWh; E.ON Next’s £3,995 for a Sunsynk Elite is about £868 per usable kWh. And the warranties differ more than the batteries: from 70% of capacity promised at year 12 (Fox ESS EVO) to no minimum at all (Sunsynk).
What 5kWh costs, and why per kWh it is the dearest
| Source | Price | What it covers |
|---|---|---|
| Octopus Energy | From £3,947 | Fox ESS EVO 5 or Enphase IQ Battery 5P, battery only, installed (April 2026 prices) |
| E.ON Next | From £3,995 | Sunsynk Elite, 5.12 kWh (4.6 kWh usable) |
| EDF | From £2,495, or £3,995 with an inverter | Sunsynk battery, two sizes (read 6 October 2026) |
| Energy Saving Trust | About £4,600 | Its guide figure for a 5 kWh system (August 2026) |
| DESNZ official median | £1,300 per kWh | MCS-certified installs under 6 kWh, 2025/26: about £6,500 for 5 kWh |
EDF’s two prices show what an inverter adds: £1,500 between the battery alone and the battery with an inverter. A battery added to existing solar can sometimes share a hybrid inverter that is already there; one added to a home with an older solar inverter, or with none, usually cannot.
The labour, the electrical connection, the network notification and the commissioning cost roughly the same for a 5 kWh battery as for a 13.5 kWh one. Spread over fewer kWh, they make the small battery the most expensive per unit of storage: the official median falls from £1,300 per kWh under 6 kWh to £630 per kWh above 11 kWh. The median for small batteries also rose from £1,080 the year before, while larger ones barely moved.
The solar battery cost guide shows the same bands with the average installation in each: roughly £6,600 for the average battery under 6 kWh in 2025/26.
What it saves
This site’s model, for a home using 3,000 kWh a year:
| Set-up | Modelled saving a year |
|---|---|
| London, 4 kWp solar, Octopus Flux | £174 |
| Glasgow, 4 kWp solar, Octopus Flux | £166 |
| London, no solar, Agile Octopus | £202 |
On these numbers a 5 kWh battery at £3,947 takes around 20 years to pay back, which is why small batteries are often best bought as part of a solar installation or as the first module of a system you plan to expand. The calculator runs your own usage.
Starting at 5kWh and adding later
Most 5 kWh products are modular, but each system has its own ceiling: Sunsynk Elite stacks take one to six modules, Sigenergy one to six per controller, Fox ESS’s EVO 10 datasheet allows three units in parallel, and myenergi’s 2023 libbi datasheet allows four 5 kWh modules. Adding capacity later means a second visit, and sometimes a new network notification if the inverter changes. It can also cost more than fitting the capacity at the start: Octopus, for example, prices the same Tesla Expansion Pack at £3,773 with a new Powerwall 3 and £5,909 added later. If you expect an electric car or heat pump within a few years, price the larger size now as well.
Is 5kWh enough, or should you go bigger?
Look at your bill. Take your yearly use, divide by 365, and assume around 60% of it falls outside daylight hours. If that evening figure is under about 5 kWh, a 5 kWh battery is well matched. If it is 7 kWh or more, or you are adding an electric car, compare a 10kWh battery quote as well: the extra capacity usually costs far less than the first 5 kWh. Our guide to whether 5kWh is enough works through it by household. Get battery storage quotes for both sizes and put them through the checker.
Questions people ask
How much does a 5kWh battery cost in the UK?
Published installed prices start at £3,947 (Octopus, a Fox ESS EVO 5 or an Enphase IQ Battery 5P, battery only, April 2026 prices) and £3,995 (E.ON Next, Sunsynk Elite, 4.6 kWh usable). EDF lists a Sunsynk battery from £2,495 on its own or £3,995 with an inverter. The official median for MCS-certified batteries under 6 kWh was £1,300 per kWh in 2025/26, about £6,500 for 5 kWh.
Which 5kWh battery gives the most usable energy?
Of the common options, Sigenergy's SigenStor BAT 6.0 gives the most, 5.84 kWh usable, followed by the Enphase IQ Battery 5P at 5.0 kWh. Sunsynk's G5.3 gives 4.79 kWh, and the Sunsynk Elite and myenergi libbi modules 4.6 kWh each. Compare prices per usable kWh, not per label.
How long will a 5kWh battery power a house?
It depends on what is running. A typical home using 3,000 kWh a year averages roughly 0.35 kW, so 5 kWh of usable energy covers around 14 hours of average use, or an evening peak of cooking, TV and lights of 1 to 2 kW for three to five hours.
Is 5kWh enough for a house?
For a smaller home with modest evening use, often yes. In this site's model a home using 2,000 kWh a year uses about 3.3 kWh a day outside daylight hours, which a 5 kWh battery covers. Homes with an electric car, a heat pump or high evening use will fill a bigger battery.
Can I add to a 5kWh battery later?
With a modular system, usually. Sunsynk Elite stacks take one to six modules, Sigenergy takes one to six per controller, myenergi's 2023 libbi datasheet allows up to four 5 kWh modules, and Enphase units can be added side by side. Adding later means another visit and possibly a new network notification, and it can cost more than fitting the capacity at the start.