Is a solar battery worth it in Wales?

A home battery is worth it only if it lets you use more of your own solar power instead of selling it cheaply. For many Welsh homes that is a close call, because the saving depends on your habits. A battery costs roughly £2,000 to £10,000. The saving comes from the gap between what you pay for power and what you earn for exports. This guide shows how to work out whether that gap pays for your battery.

What a battery actually does

Solar panels make power in the day, yet many households use more in the evening. Without a battery, the spare daytime power goes to the grid. With one, you store it and use it after dark. As a result, you buy less from your supplier.

A battery does not make power. It moves power from the afternoon to the evening. That is why the question is never “does it work”, but “does the stored power earn back its cost”.

The numbers behind the decision

Start with the price of a kilowatt-hour you buy. From October to December 2026, the Ofgem price cap averages about 26p per kWh for electricity. In contrast, Ofgem’s 2024-25 report found an average export payment near 4.4p on untied tariffs. The highest untied rate was 12p, and tied tariffs averaged about 14.5p.

Therefore, a kilowatt-hour stored and used at home is worth roughly 22p more than one exported on an average untied tariff. That is our own comparison of two Ofgem figures from different periods, so treat it as a guide. Read our post on the Smart Export Guarantee to see how tariffs differ.

The size of the gain depends on how much you export. For example, a home with a small array and a person at home all day exports little, so a battery adds little. A larger array with an empty house at midday exports much more. Our guide to how many panels you need helps you judge that balance.

What a battery costs

The Energy Saving Trust puts a home battery at around £5,000 to £8,000, while Which? gives a wider range, from under £2,000 to £10,000, depending on capacity, type and brand. A battery bought with new panels usually costs less than one added later.

Batteries qualify for 0% VAT. The relief has applied since 1 February 2024, whether you add the battery to an existing system or install it alone. A battery fitted at the same time as panels counts as part of one supply and gets the same VAT rate. However, the 0% rate ends on 31 March 2027, when 5% is due to apply.

For the panel side of the bill, see our solar panel costs in Wales post. It sets out the price per kilowatt from government data, since panels and battery prices work differently.

When a battery makes sense

A battery suits some households better than others. These are the cases where it is most likely to pay off:

• You are out all day and use most of your power in the evening.
• You have a larger array that exports a lot at midday.
• You plan to charge an electric car, or run a heat pump, in the evening.
• You are on a tariff that pays well for stored power and exports.

Electric cars change the sums. However, timing matters: if you charge in the day, your panels can feed the car directly. If you charge at night, a battery can help. We look at this in our post on charging an electric car with solar.

When it probably does not

A battery is harder to justify if someone is home all day and uses the power as it arrives. As a result, little is left to store. A small array on a shaded roof has the same problem. Meanwhile, the panels alone may already deliver most of the saving.

Remember too that a battery adds equipment that can fail, so check what the warranty covers. Ask about the warranty, the expected cycle life and who services it. We have no verified figure for how long Welsh home batteries last, so do not rely on a sales claim without paperwork.

Installers and standards in Newport, Bridgend and Barry

Battery work needs the right certification. MCS publishes a battery standard, MIS 3012, which covers batteries up to 50 kW in permanent buildings. A quote that includes battery self-consumption should make clear if the installer is not certified to that standard.

If you live in the south east, compare solar installers serving Newport and firms around Bridgend. Homes along the coast can also look at installers covering the Barry area. Our solar battery storage page lists what to ask each firm.

Grid rules for batteries

Batteries count towards the size limit for grid connection. Small generators of 16 amps per phase or less, which is 3.68 kW on a single-phase supply, follow the simpler G98 route. Larger ones, and larger combined solar and storage systems, follow G99. Under G99 the installer must agree the connection before commissioning.

Your installer normally handles this paperwork. Still, ask which route applies and who sends the forms, because delays can hold up commissioning. Our grid and export guide explains both routes in plain terms.

Getting help with the cost

Green Homes Wales can fund solar panels with a battery for owner-occupiers. It offers interest-free loans of £1,000 to £25,000 over up to 10 years, run by the Development Bank of Wales. The home must be your main residence and not a new build or listed. Funding depends on availability, so check before you plan around it.

Warm Homes Nest may include solar for eligible low-income homes, but a battery is not promised. Our Welsh solar funding guide lists the rules and the schemes that do not apply in Wales.

A simple way to decide

Because every home differs, first look at a year of electricity bills and note how much you use in the evening. Second, ask each installer for an estimate of how much of your solar power you would use with and without a battery. Third, price the battery as a separate line, so you can see what it adds.

If the extra saving takes longer to repay than the battery’s warranty, think again. You can always add a battery later, and the 0% VAT currently applies to that too. Our form can pass your enquiry to MCS-certified installers, and we are a guide and referral service, not an installer.