Key takeaways
- A typical home battery is 5–10kWh and costs £2,000–£4,000 installed
- Batteries don't save money on their own. They need solar panels or a smart tariff to pay back
- With solar, a battery increases self-consumption from ~50% to ~80%
- With a smart tariff, you can charge cheap overnight electricity and use it during peak hours
- Payback is typically 8–14 years with solar, longer without
- Battery warranties are typically 10 years / 60–80% retained capacity
The short answer
A home battery does not save money on its own. It pays back paired with solar, storing generation you would otherwise export at 4–15p instead of buying at 26.11p, or paired with a smart tariff, charging at about 7.5p overnight and discharging at peak.
A 5–10kWh battery costs £2,000–£6,000 installed. Payback is 8–14 years with solar and longer without, and warranties typically run 10 years to 60–80% retained capacity. Size it to your evening usage, not to the largest unit quoted.
What a home battery actually does
A home battery stores electricity for later use. The two main scenarios where this saves money:
- With solar panels: Instead of exporting excess solar generation at 4–15p/kWh, you store it and use it in the evening when you'd otherwise buy grid electricity at 26.11p/kWh. This is the "self-consumption" benefit. (New to panels? See our best solar panels for UK roofs.)
- With a smart tariff: You charge the battery during cheap overnight rates (e.g., 7.5p/kWh on Octopus Go) and discharge it during peak hours (26.11p/kWh). This is "tariff arbitrage."
You can also combine both, solar charging during the day, cheap grid top-up overnight.
Battery sizes and costs
| Capacity | Typical cost (installed) | Best for | Daily usage covered |
|---|---|---|---|
| 5kWh | £2,000–£3,000 | Small home, low usage, or adding to existing system | Covers an evening's usage (2–3kWh typical) |
| 7.5kWh | £3,000–£4,500 | Average UK home | Covers evening + overnight baseload |
| 10kWh | £4,000–£6,000 | Larger home, EV charging, high usage | Covers a full day's non-heating usage |
| 13.5kWh (Tesla Powerwall) | £7,000–£9,000 | Large home, full backup | Full day's usage including some heating |
Installation typically adds £500–£1,500 to the battery cost. Most batteries are wall-mounted indoors (garage or utility room) and need a dedicated circuit from your consumer unit.
Sizing. How big a battery do you need?
The right size depends on your usage pattern:
- Solar self-consumption: Size the battery to your evening usage (typically 3–5kWh). Oversizing means the battery won't fill up on cloudy days.
- Tariff arbitrage: Size the battery to cover your daytime usage when rates are high (typically 5–8kWh).
- Both: 7.5–10kWh is the sweet spot for most homes.
Rule of thumb: Check your evening electricity usage (typically 5pm–11pm) on your smart meter data. A 5kWh battery covers most of it. If you have high evening usage (cooking electric, etc.), go for 7.5–10kWh.
Get a number, not a range
Our battery size calculator turns your daily usage, solar setup and tariff into a recommended size, installed cost and annual saving in about thirty seconds.
Does battery storage pay back?
Honest answer: it depends heavily on your setup.
With solar panels
A battery increases your solar self-consumption from roughly 50% to roughly 80%. On a typical 4kW system generating 3,400kWh/year:
- Without battery: ~1,700kWh used directly, ~1,700kWh exported at ~5p = £85 export income
- With 5kWh battery: ~2,700kWh used directly, ~700kWh exported = £35 export income
- Battery saving: ~1,000kWh × (26.11p - 5p) = ~£210/year
On a £2,500 battery, that's roughly a 13-year payback. On a £4,000 battery, it's 20+ years. Which is at or beyond the warranty period.
With a smart tariff (no solar)
With Octopus Go (7.5p/kWh overnight, 26.11p/kWh peak):
- Charge 5kWh at 7.5p = 37.5p
- Use 5kWh at 26.11p = £1.31 (what you'd pay without the battery)
- Daily saving: 94p → ~£340/year
On a £2,500 battery: ~7-year payback. This is more viable. We cover the tariffs, the sizing and the catches in detail in our overnight charging guide, and no, you do not need solar for it.
Battery storage is not a standalone money-saver
A battery without solar or a smart tariff doesn't save money. It just stores electricity you could use directly. The savings only come from time-shifting electricity use. If you're on a standard flat-rate tariff with no solar, a battery doesn't make financial sense.
Before committing to battery storage, it's worth checking whether the bigger savings sit elsewhere. Our insulation payback calculator shows how quickly loft, cavity and floor insulation pay back, usually 2–5 years, beating most battery setups.
Popular battery brands in the UK
- Tesla Powerwall 3, 13.5kWh, ~£7,500–£9,000 installed. Premium, high capacity, good app. Long lead times.
- GivEnergy, 5–13.5kWh, ~£2,000–£5,500. UK-manufactured. Popular with installers. Good value.
- SolarEdge, 5–10kWh, ~£3,000–£5,000. Integrates with SolarEdge inverters. DC-coupled for better efficiency.
- Enphase IQ Battery, 5–15kWh, modular. AC-coupled, easier to retrofit. ~£2,500–£5,000.
- Myenergi Libbi. 5–10KWh, ~£2,500–£4,500. Works well with Myenergi ecosystem (Zappi charger, Eddi diverter).
Model your solar + battery savings
Enter your system size, usage pattern, and tariff to see whether a battery makes sense for you. Solar + Battery Calculator →
Installation considerations
- Location: Needs indoor installation (garage, utility room). Batteries perform best at 15–25°C. Not suitable for unheated sheds in winter.
- Electrical: Needs a dedicated circuit from your consumer unit. If your CU is full, you may need an upgrade (~£200–£500).
- Planning: No planning permission needed for battery installation inside your home.
- Warranty: Most batteries come with a 10-year warranty guaranteeing 60–80% retained capacity. After warranty, replacement cells are typically £1,000–£2,000.
A plug-in energy monitor or smart plugs reveal your evening load — the figure that decides the battery size worth paying for.
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Sources
Energy Saving Trust, MCS, manufacturer specifications, Ofgem price cap data for 1 July to 30 September 2026. Costs are indicative and vary by installer and region.