Saving without battery£758
Saving with battery£900
Battery cost (example)£3,500
Your region
Worked out for UK average at today's electricity price of 26.32p per kWh. 4.5 kW system; 40% used at home without a battery, 70% with one.
The short answer
Without a battery, most homes use only 20 to 40% of their solar power themselves, and export the rest at a lower price. With a well-sized battery, that can rise to 60 to 80%.
The numbers for a typical home
| Without battery | With battery | |
|---|---|---|
| Used in your home | about 40% | about 70% |
| Yearly saving | £758 | £900 |
| Typical cost | £7,600 | about £11,100 (with a £3,500 battery) |
| Payback | 10 years | 12 years |
Battery prices vary widely. Which? reports supplier prices starting from around £2,500 to £4,000 for a home battery. We've used £3,500 as an example.
When a battery makes most sense
- You're out during the day and use most electricity in the evening.
- Your export rate is low. If you only get 3 to 4p for exports, storing power to use later is worth far more.
- You use a time-of-use tariff. Some tariffs let you charge the battery cheaply overnight and use it at peak times, which can add savings even in winter.
- You're fitting panels anyway. Installing both together saves on labour.
When it might not
- You're home all day and already use most of your solar power.
- You have a high export rate, such as 15p or more.
- The battery would take longer to pay back than its warranty lasts. Check the warranty, often around 10 years.
Try it both ways in the solar payback calculator.
Sources: OpusFlow, Energy Saving Trust figures via Which?, Utilita, Octopus Energy tariff data.