Are solar batteries worth it? Costs, savings and payback

Solar panels on the tiled roofs of brick houses

A home battery is worth it if you will use it every day to avoid expensive electricity, usually by charging it on a cheap overnight tariff as well as from your panels. Used only to soak up spare solar power, a battery typically saves around £100 a year, which does not repay a £4,600 outlay within its life.

What a battery costs in 2026

MoneySavingExpert, updated 1 October 2026, gives these fitted prices:

Battery size	Typical fitted price
3 kWh	about £3,500
5 kWh	about £4,600
7 kWh	about £5,500

Cheaper and dearer systems exist, from about £1,500 to £10,000. Fitting a battery with new panels usually costs less overall: one supplier prices 12 panels with a 10 kWh battery at £11,115 (April 2026 prices).

MoneySavingExpert puts battery life at about 12 to 15 years, against roughly 25 years for the panels. Plan on replacing a battery at least once over the life of a solar system.

How a battery saves money

There are two ways a battery earns its keep. Most people need both for the numbers to work.

1. Using more of your own solar power

Without a battery, solar power you do not use at the time goes to the grid. You are paid an export rate for it, then buy power back in the evening at the full price.

The value of each stored unit is the difference between the two:

Price cap electricity, October to December 2026: 26.32p per kWh (Ofgem)
A common export rate: 12p per kWh (Outgoing Octopus, October 2026)
Value of storing that unit instead: about 14p per kWh

That 14p is the whole prize. If you are on a better export rate, the prize shrinks. See Smart Export Guarantee rates.

2. Charging on cheap overnight electricity

Time-of-use tariffs sell electricity cheaply for a few hours at night. You charge the battery then and run the house from it at peak times.

On 17 October 2026, Octopus Go 12M Fixed in the Midlands region charged 9.5p per kWh from 00:30 to 05:30 and 33.89p at other times. The gap is about 24p per kWh, much bigger than the 14p from storing solar alone.

The catch: the day rate on that tariff is higher than the price cap. A battery is what stops you paying it.

Payback: three honest scenarios

These are our calculations, using the figures above. They ignore charging losses, battery wear and future price changes, all of which make the real result a little worse.

Scenario	Assumptions	Saving a year	Payback on a £4,600 battery
Spare solar only	MoneySavingExpert model: 4.6 kWp south-facing array, MCS “home all day” tables, export valued at 15p	£84 to £106	29 to 44 years (their figures, varying with the number of panels)
Spare solar, our check	5 kWh battery, value 14p per kWh, would need about 2,140 kWh shifted a year to break even in 15 years	£307 needed	Only if it fully cycles almost 6 kWh every day of the year
Cheap night tariff	5 kWh charged nightly at 9.5p, used instead of 33.89p, 365 days	up to about £445	about 10 years, best case

The middle row shows why solar alone struggles. In Shropshire, a 4 kW south-facing system makes about 130 kWh in December according to PVGIS for Shrewsbury, roughly 4 kWh a day for the whole house. There is often nothing spare to store in winter.

The third row is a ceiling, not a promise. It assumes you use the full 5 kWh at peak every day, and it ignores the losses in charging and discharging.

When a battery makes sense

You use a lot of electricity in the evening and overnight, for example with an electric car, a heat pump or electric cooking. See our heat pump guides.
You will switch to a time-of-use tariff and are happy to let the battery charge automatically at night.
You are fitting solar now. Sharing scaffolding and electrical work keeps the combined price down, as shown in our solar panel cost guide.
Your export rate is low. On 3p or 4p export, every stored unit is worth more.

It makes less sense if you are out all day on a standard tariff with a small system. If backup power during a cut matters to you, ask the installer whether the system they quote provides it.

Retrofit batteries and 0% VAT

HMRC added batteries to the energy-saving materials relief from 1 February 2024. Its guidance covers:

A battery retrofitted to an existing solar system.
A standalone battery that stores electricity from the grid, with no panels at all.

The zero rate runs until 31 March 2027, then is due to revert to 5%. It only applies when the installer supplies and fits the battery; a battery bought on its own is standard-rated.

One rule on exporting from a battery

If you charge from the grid at night and export by day, the supplier may not pay for it. Ofgem’s guidance says Smart Export Guarantee payments are only required for “green export” from the eligible installation. Electricity from a battery charged from the grid is “brown export”, and suppliers can choose whether to pay for it.

Some export tariffs are designed for battery owners and do pay. Read the terms before assuming income.

Questions to ask an installer

What usable capacity (kWh) does the battery have, and what warranty in years and cycles?
Can it charge from the grid on a time-of-use tariff?
What saving do you estimate, and what tariff and export rate does that assume?
Is VAT at 0% on the quote, and when will it be fitted?

Weighing up a battery? Get a quote from a checked local installer.

Common questions

How long does a solar battery take to pay for itself?

It depends almost entirely on how you use it. Storing spare solar alone gives payback of roughly 29 to 44 years in MoneySavingExpert's October 2026 model, longer than a battery lasts. Charging nightly on a cheap tariff can bring it nearer 10 years in a best case, before charging losses.

Can I add a battery to my existing solar panels?

Yes. HMRC says a battery retrofitted to existing solar panels qualifies for the 0% VAT rate, as does a standalone battery charged from the grid, provided the installer supplies and fits it before 31 March 2027.

Do I get paid for exporting electricity from my battery?

Only for green export. Ofgem's guidance says suppliers do not have to pay Smart Export Guarantee rates for electricity from a battery charged from the grid, though some choose to. Check the tariff terms.

What size battery do I need?

Match it to your evening and overnight use, not your roof. A battery that never fills in winter or never empties in summer is money spent for nothing. An installer should size it from your half-hourly smart meter data.