Is a solar battery worth it?

How much does a solar battery save?

A battery added to solar panels saved about £210 a year with a good export rate (15.6p) and over £400 with a standard one (4p), in the Energy Saving Trust's 2026 modelling of a gas-heated home at April 2024 tariffs [1]. With the good rate, payback took longer than the battery's expected life [1]. Where savings approached £500, payback was about 13 to 15 years, partly because of tariff changes rather than the battery itself [1]. That still runs past the 10 to 12 years the Energy Saving Trust gives as a typical battery life [3], a typical figure rather than a fixed end date for every product.

A battery saves money in two ways. It stores solar electricity you would otherwise export, so each stored kWh saves the import price but loses the export payment. On a time-of-use tariff, it can also charge cheaply overnight and run the house at peak times [2]. Without a time-of-use tariff the first is the only saving, and the export rate decides how much it is worth.

How much would a battery save in my home?

For two households used as examples by the Microgeneration Certification Scheme (MCS), a battery adds 1,203 to 1,624 kWh a year of solar used at home, worth roughly £160 to £370 a year at today's prices, by our calculation [4][5]. That puts the simple payback at 20 to 47 years. These figures cover storing solar only: they leave out charging from the grid overnight, and they price the battery from government median rates, not a quote. A third MCS example, C, uses only part of its battery for solar, so its row counts part of the benefit against the whole cost.

The export income given up is real money: by our calculation, household A would lose about £220 a year of export payments at 12p, set against about £430 of electricity it no longer buys. MCS says its estimates cover the first year only and are not a guarantee [4]; battery capacity fades over time and prices change, so later years may differ.

What if your quote is lower?

Simple payback is the price divided by the yearly saving, so your quote decides it. The table shows the most each battery could cost and still repay itself from these solar savings within 10 or 12 years. Our estimated costs for A and B come out almost the same although B's battery is smaller: B's estimated nominal size falls just under 6 kWh, where the median price per kWh is higher [16]. That is why the break-even price is the better test. The Energy Saving Trust's figure of around £4,600 for a 5 kWh system, given without a basis, is above every break-even price for B, the closest in size [3].

When is a solar battery not worth it?

A solar battery is unlikely to recover its cost on solar savings alone when its payback is longer than its life. In both full worked examples the payback runs past the 10 to 12 years the Energy Saving Trust gives as a battery's typical life [3]. The Trust's own modelling reached the same answer for a home on a good export rate [1]. The case is weakest when:

• You already get a good export rate. The more each exported kWh earns, the less a battery saves by keeping it [1].
• Little of your use falls in the evening. A battery stores daytime solar for later; if the house uses little after dark, there is less to shift.
• The battery is bigger than the solar it can fill. Capacity that solar cannot fill adds cost without adding solar savings.

Before paying for a battery, check your export rate. Suppliers set their own Smart Export Guarantee rates, which Ofgem requires only to be above zero [6]. In 2024-25, the average rates paid were 15.4p per kWh on tied export tariffs and 7.3p on untied ones, Ofgem reports; these are past averages, not rates you can get today, and some of the highest tied rates require a battery [7]. Moving the same households from a 3p to a 12p export rate earns more export income each year, with no equipment to buy, though a tied rate means meeting its conditions:

Export rates and their conditions are compared in the best export tariffs.

When does a battery earn more?

A battery earns more where it can charge cheaply and replace expensive electricity, on a time-of-use tariff. The Energy Saving Trust found batteries "better paired with heat pumps than with solar panels" on the right tariff [2]. In its modelling of a heat pump home without solar, a battery saved up to around £570 a year on a dynamic tariff, for a home switching from a standard tariff; part of that saving comes from the tariff switch [1]. Some tariffs are built for solar and a battery: Octopus Flux, for example, requires both [12]. In London on 13 October 2026 it charged 14.56p per kWh from 2am to 5am and 33.96p from 4pm to 7pm [10], and paid 28.60p for export from 4pm to 7pm [11]. Rates vary by region and change.

A battery also protects you if export rates fall, the Energy Saving Trust notes [2]. The battery sizing guide covers how big a battery a home can use.

Pros and cons of solar battery storage

Do you need a solar battery? No, solar panels work without one: in the MCS examples, homes use 29 to 39 per cent of their solar directly and export the rest [4]. Whether you should get one comes down to the trade-offs below.

Is a battery worth it for power cuts?

Backup in a power cut is a separate reason to buy, and it can need extra equipment. Tesla's Powerwall 3, for example, needs its Backup Gateway 2 for any backup set-up [15]. Whether that is worth paying for depends on how many power cuts you get and what you need to keep running; it is not part of the savings above. Prices for batteries and gateways are on solar battery costs.

What could change the sums?

Two dates matter. There is no VAT on electricity from 1 October 2026 to 31 March 2027, so the 26.32p used above has none [5]. A battery supplied and installed in a home is zero-rated for VAT until 31 March 2027, with 5 per cent due from 1 April 2027; bought without installation, it is standard-rated [17]. Ofgem updates the price cap every three months [13]; a higher import price makes each stored kWh worth more.