Is a solar battery worth it?
A battery lets you use more of your own solar power instead of exporting it, but on solar savings alone it rarely pays for itself quickly. It tends to make most sense if you’re out during the day, use a time-of-use tariff, or have an electric car or heat pump. The best way to decide is to ask installers to quote with and without one.
Last reviewed 21 October 2026. Sources are listed at the end of this page.
Each unit stored
Saves about 14p
The gap between a 26.32p import price and a 12p export rate.
Typical cost
£5,000 to £8,000
Energy Saving Trust figure. Size and installation change the price.
VAT on batteries
0% to March 2027
Until 31 March 2027, with new panels or added later.
What a battery actually changes
Without a battery, solar power you don’t use straight away goes to the grid. You’re paid for it under the Smart Export Guarantee, typically around 12p a unit according to the Energy Saving Trust. Buying a unit from the grid costs more than twice that: the price cap unit rate for October to December 2026 is 26.32p.
A battery stores your spare daytime power so you can use it in the evening. So each unit it shifts saves you roughly the gap between the two prices, about 14p a unit at those rates. That gap is the battery’s main source of savings, and it changes whenever tariffs change.
Two worked examples
These are illustrations, not estimates for your home. Both assume a 4kW system generating 3,600kWh a year, an import price of 26.32p and an export rate of 12p. The shares of power used at home are assumptions chosen to show the pattern. Your installer can model your own usage.
Solar used at home without a battery (assumed)
A · Out by day
30% (1,080kWh)
B · Home by day
50% (1,800kWh)
Solar used at home with a battery (assumed)
A · Out by day
60% (2,160kWh)
B · Home by day
70% (2,520kWh)
Units shifted by the battery each year
A · Out by day
1,080kWh
B · Home by day
720kWh
Extra value from the battery each year
A · Out by day
About £155
B · Home by day
About £105
Two things stand out. A battery adds more for the household that’s out during the day, because more of its solar would otherwise be exported. And in both examples the extra value is around £100 to £160 a year, against a battery cost that the Energy Saving Trust puts at around £5,000 to £8,000. On solar savings alone, a battery may not pay for itself within its typical life of 10 to 12 years.
When a battery makes more sense
You use a time-of-use tariff
Extra savings
A battery can charge from the grid when electricity is cheap, often overnight, and power your home at peak times. This can add savings on top of storing solar power, especially in winter when panels generate less.
You have an electric car or a heat pump
Saves more
The Energy Saving Trust says a battery saves more when it supports a heat pump than when it only stores spare solar power.
You want backup or independence
Check the system
Some systems can keep essential circuits running in a power cut. Check, because not all can.
You’re installing everything at once
Lower fitting cost
Fitting a battery at the same time as panels can share the inverter, scaffolding and labour costs.
What batteries cost
The Energy Saving Trust says battery storage tends to cost around £5,000 to £8,000, and that a 5kWh battery costs around £4,600. Prices depend on capacity, brand, whether a new inverter is needed and how hard the installation is.
Installing a battery is currently VAT-free until 31 March 2027, whether it’s fitted with solar panels or added later.
Adding a battery later
You don’t have to decide now. Many households fit panels first and add a battery later, once they know their usage. If you might, ask your installer to choose an inverter that can take a battery later, or one that’s battery-ready. Fitting a battery later usually costs more than fitting both at once.
Questions to ask an installer
• Can you quote with and without a battery, and show how much of my solar power I’d use in each case?
• What import and export prices did you assume, and what does the saving look like if they change?
• What size of battery suits my usage, and why?
• Is the inverter battery-ready if I add one later?
• What warranty covers the battery, for how long, and what capacity is guaranteed at the end of it?
• Will the battery keep any circuits running in a power cut?
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Frequently asked questions
A few things worth knowing before you start.
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SOURCES
Where this guide’s information comes from
Last reviewed 21 October 2026. Prices and tariffs change, so check the sources below before you act.