If you already have solar panels, adding a battery could help you make more use of the electricity you generate. Whether it makes sense depends on your energy use, your export tariff, your existing equipment and what you want from a battery.
Once you start looking into it, the questions soon follow:
In this guide, we answer these questions about retrofitting a solar battery and share some practical tips for UK homeowners.
In short: yes. Most homes can add a battery to an existing solar system. There are two main ways to do this – an AC-coupled battery or a hybrid inverter.
An AC-coupled battery has its own inverter, separate from the one your solar panels already use. Your existing solar setup stays as it is, and the battery connects to your home’s electricity supply. This is often the simplest option if your current inverter is still fairly new.
A hybrid inverter replaces your existing solar inverter with a single unit that controls both your solar panels and your battery. Solar power can charge the battery directly, with fewer conversions, so less energy is lost along the way. It also means less equipment on the wall. A hybrid inverter often makes the most sense when your existing inverter is due to be replaced.
An inverter converts the direct current (DC) electricity from your solar panels or battery into the alternating current (AC) electricity your home uses.
The best option for you depends on the age of your current inverter, the space you have available and your budget. With an AC-coupled battery, your existing inverter stays in place, so you pay for the battery unit (with its built-in inverter) and its installation. A hybrid inverter also involves the cost of a new inverter – but if your current inverter needs replacing soon anyway, combining the two saves you paying for two separate jobs. Your installer will look at your existing system and recommend the best fit.
Adding a battery to your existing solar panels is most worthwhile in four situations.
With a suitable setup, a battery can keep selected appliances running when the grid goes down, such as your fridge and freezer, lights, broadband and phone chargers. Storms have caused long power cuts in parts of the UK in recent winters, so for some households this is an important consideration.
If backup power matters to you, choose a system with an emergency power supply (EPS) or backup function, as not every battery has one. Let your installer know at the start, so they can recommend a suitable setup. Read more in our guide: Do solar panels work during a power outage?
The Feed-in Tariff (FIT) was a government scheme that paid households for the electricity their solar panels generated and exported. It closed to new applicants in 2019, but households already on it are still paid until their contract ends. For solar panels installed since then, the main way to be paid for exported electricity is the Smart Export Guarantee (SEG).
Under the SEG, certain electricity suppliers pay you for the electricity you export, at rates that vary between suppliers. Most export tariffs pay less than you pay to buy electricity from the grid – an average of 26.32p per kWh under the current price cap.
So the focus is shifting from selling your solar power to using it yourself. A battery stores your daytime surplus for the evening, which can reduce how much electricity you buy from the grid and lower your bills. The size of the saving depends on your household and your tariff. You can still get SEG payments with a battery. And if you’re on a time-of-use tariff, which has lower prices at off-peak times such as overnight, you can also charge your battery when electricity costs less.
Solar panels typically last around 25 years, but the inverter usually needs replacing after about 10 to 12 years, according to the Energy Saving Trust. If your inverter is reaching the end of its life or its warranty, it’s a good moment to consider a hybrid inverter, so you can add a battery at the same time. That can work out better than a like-for-like replacement now and a battery later. But a battery still adds to the cost, so it’s worth comparing both options.
If your solar panels were registered for the Feed-in Tariff before it closed on 31 March 2019, you receive FIT payments. These last for 20 years, or 25 years for installations before August 2012, so the first FIT contracts will start to end in the early 2030s. When your FIT payments end, the savings on your electricity bill become the main financial benefit of your solar panels. So making the most of the solar power you generate yourself becomes more important – and a battery can help you do that.
You can add a battery while you’re still getting FIT payments. But Ofgem requires you to tell your FIT supplier when you connect battery storage, and your system must still measure your solar generation separately from the battery. If it can’t, you can lose payments for that electricity. Make sure your installer is familiar with these rules before the work starts.
You now know the benefits of adding a battery – for both power cuts and lower bills. But what most people really want to know is the cost of a retrofit.
According to MCS Dashboard data for 2025, the average fully installed home battery system in the UK costs £6,819, or an average of £1,413 per kWh of storage. These averages cover a wide range of system sizes and setups, so they are a starting point rather than a guide to what your retrofit will cost.
In practice, the cost per kWh tends to fall as capacity increases. It also depends on the brand, the type of battery and the condition of your existing system – for example, whether you also need a new inverter. So capacity and cost don’t rise in a straight line. See our solar battery price guide for more detail.
There is support available from the UK government, from the governments of Scotland, Wales and Northern Ireland, and from some local councils:
Eligibility and funding change regularly, so it’s worth checking what is available in your area. See our guide to solar battery grants to make sure you get the best value from your retrofit.
The right battery for your home depends on where it will be installed, what you want it to do and how much electricity your existing solar panels generate. And a bigger battery isn’t always better.
To avoid paying for capacity you won’t use, choose a battery that balances what your panels generate with what your household uses. A battery that your panels can rarely fill may be oversized – unless you also plan to charge it on an off-peak tariff, or you expect to use more electricity in future, for example with an electric vehicle. Our solar panel output calculator can help you estimate how much your panels generate.
Through Switch Together, households with existing solar panels can add a battery at a competitive price. Our council-backed schemes use group buying to secure competitive prices from vetted, MCS-certified installers. After you register, you receive a personalised offer for your home, with an estimate of the costs.
Registration is free, and there is no obligation. Find out how group buying works.
Even if you already have solar panels, you can add battery storage. With export payments lower than the price of grid electricity, and energy bills still high, the focus is shifting towards using the solar power you generate yourself. If your inverter is due for replacement, or your Feed-in Tariff is coming to an end, it’s a good time to assess whether a battery makes sense for you.
Group buying and the support available, such as 0% VAT, can reduce the cost. Your first step is to get expert advice on the right battery capacity for your home.
Our expert team is here to help you every step of the way.
Join the switch: register with Switch Together to receive your free, no-obligation personal recommendation for adding a battery to your solar panels.