In short
- A home battery stores electricity, from solar panels or from the grid at cheaper times, so you can use it later.
- The Energy Saving Trust puts the cost at around £5,000 to £8,000, and Home Energy Scotland says batteries tend to last 10 to 15 years.
- Batteries suit some households much better than others. They tend to make most sense if you export a lot of solar electricity or can use a time-of-use tariff.
- A battery doesn't always pay back its cost, so it's worth working through the numbers for your own home.
How a home battery works
A home battery charges when electricity is plentiful or cheap and discharges when you need it. If you have solar panels, it can store electricity generated during the day for use in the evening, when your panels produce little or nothing. If you're on a time-of-use tariff, it can charge from the grid overnight or at other off-peak times and power your home during the more expensive peak hours.
Most batteries do both. The aim is the same either way: to use less electricity from the grid at full price.
Who tends to benefit
A battery is more likely to be worth considering if:
- you have solar panels and export a large share of what they generate, often because you're out during the day
- you're on, or willing to switch to, a time-of-use tariff with a big gap between off-peak and peak prices
- you use a lot of electricity, for example with a heat pump or an electric car
A battery is less likely to pay back if you use relatively little electricity, or if you already use most of your solar electricity as it's generated.
What it costs
The Energy Saving Trust puts the cost of battery storage at around £5,000 to £8,000. The price depends mainly on:
- Capacity. Larger batteries store more but cost more. What matters is the usable capacity, which can be less than the headline figure.
- How it connects. Fitting a battery at the same time as solar panels can share equipment such as the inverter, which may cost less than adding one later.
- Installation. Where the battery goes and how far it is from your consumer unit both affect the price.
Batteries for homes are currently zero-rated for VAT until 31 March 2027, whether you fit one alongside new solar panels or add it to an existing system.
Thinking about a battery?
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Working out whether it's worth it
You can get a rough idea yourself before you speak to installers:
- Look at your electricity use. If you have a smart meter, your supplier's app may show when during the day you use electricity. Evening use is what a battery mostly replaces.
- Check what you export. If you have solar panels, your export meter readings or statements show how much you're sending to the grid.
- Compare your tariff's prices. The bigger the difference between the price you pay to charge the battery and the price you'd otherwise pay, the more each stored unit saves.
- Estimate the yearly saving. Ask installers to estimate this from your real usage, including lost export income.
- Compare it with the cost and lifespan. Divide the cost by the yearly saving to get a rough payback period, then compare that with a working life of around 10 to 15 years.
Choosing the right size
Bigger isn't always better. A battery that's much larger than your evening use, or larger than the surplus your solar panels produce, may rarely fill or empty, which lengthens the payback. A good installer will size the battery from your actual usage rather than offering a standard size.
Practical things to consider
- Where it goes. Batteries are often fitted in a garage, utility room or loft, or outside if the unit is rated for it. They're heavy and need a suitable wall or floor, and very hot or cold spaces can affect performance.
- Power cuts. Not every battery keeps your home running during a power cut. Backup power usually needs specific equipment, so ask if it matters to you.
- Warranty. Check how many years the warranty lasts and how much capacity the manufacturer guarantees the battery will keep over that time.
- Tariffs. Some tariffs are designed for battery owners. A smart meter is usually needed to use them.
Help with costs
Beyond 0% VAT, the government's Warm Homes Plan includes support for batteries through low- and zero-interest loans and through help for low-income households. Details are being rolled out in stages, so check GOV.UK for what's available now. In Scotland, Home Energy Scotland can advise on support where you live.
Questions to ask an installer
- What usable capacity are you recommending, and how did you decide on it?
- What yearly saving do you expect, and does that include lost export income?
- Which tariffs would suit this setup?
- Where would the battery go, and does it need any protection from heat or cold?
- Will it provide backup power during a power cut?
- What does the warranty cover, and for how long?
This guide is general information, not financial or professional advice. Prices, grants and rules change, so check the sources below before you make a decision. EnergyAdvise is a matching service and doesn’t install products itself.
Sources
- Solar panels: costs, savings and benefits explained (battery storage costs), Energy Saving Trust
- Battery storage, Home Energy Scotland
- Warm Homes Plan, GOV.UK
- VAT on energy-saving materials and heating equipment (VAT Notice 708/6), GOV.UK