Are solar batteries worth it in the UK?
A solar battery stores the power your panels make in the day so you can use it at night, instead of selling it cheaply and buying it back at full price after dark. It can lift your savings, or sit there barely paying for itself. The difference comes down to cold maths: what the battery costs, how many extra units it lets you use yourself, and whether you're on a tariff that lets it earn its keep overnight. This guide runs those numbers for a typical UK home.
What a battery does, and what it costs
Without storage, a home typically uses 30 to 50% of its solar generation as it happens; the rest is exported at the lower Smart Export Guarantee rate. A battery captures that daytime surplus and releases it in the evening, pushing self-consumption up to roughly 60 to 80%. Every unit it shifts from "exported at 15p" to "used instead of buying at 25p" is worth the 10p gap.
A typical home battery of 5 to 10 kWh costs £3,000 to £6,000 installed. That's the number the savings have to beat.
| Item | Typical figure |
|---|---|
| Usable battery size | 5 to 10 kWh |
| Installed cost | £3,000 to £6,000 |
| Self-consumption without a battery | 30 to 50% |
| Self-consumption with a battery | 60 to 80% |
| Warranty | ~10 years / ~6,000 cycles |
The payback maths on solar alone
Take a 5 kWh battery that shifts an extra 1,200 kWh a year from export to self-use. At a 10p spread between what you avoid (25p) and what you'd have been paid to export (15p), that's about £120 a year. On a £4,000 battery, that alone is a payback past 12 years, close to the warranty. On solar self-consumption by itself, a battery is often marginal. That's the honest headline, and it's why storage is a separate decision from the panels, as set out in do I need a battery.
Where a battery actually earns its money: smart tariffs
The maths changes the moment you add a time-of-use tariff. On a tariff with a cheap overnight window of around 7p, you can charge the battery from the grid at night and run the house on it during peak hours when units cost far more. That's arbitrage on top of solar self-use, and it can roughly halve the payback. The detail on which tariffs suit a battery is in the best smart tariffs for solar, batteries and EVs.
So the real question isn't "is a battery worth it?" in the abstract. It's "is a battery worth it on my usage and my tariff?" Two homes with identical panels can get very different answers.
When a battery is worth it
- High evening and night usage. If most of your demand is after dark, a battery shifts a lot of solar into the hours you actually use power.
- You're on, or will switch to, a time-of-use tariff. Overnight charging plus peak avoidance is where the strong returns are.
- You want backup. Some batteries keep essential circuits running in a power cut, a feature you have to ask for specifically.
- You're adding an EV or heat pump. More electrified demand gives a battery more to do, as covered in solar, heat pumps and EVs.
When it isn't
- Low overall usage on a standard tariff. There simply isn't enough spread to recover the cost inside the warranty.
- You're home all day. If you already use most of your generation as it's made, a battery has little surplus left to store, a pattern that's sharpest in the cloudy months covered in solar in a UK winter.
- Purely as a financial play with no tariff change. On current prices, panels usually have the stronger standalone return; the combined payback is in solar panel payback.
The detail most people miss
Batteries are rated by usable capacity, cycles and round-trip efficiency, and these vary between brands. A battery that loses 10 to 15% of energy on each charge-discharge cycle quietly eats into the spread you're chasing. So does oversizing: a battery bigger than your daily surplus and evening demand spends much of the year part-empty, which is money parked rather than working. Right-sizing to your actual daily pattern matters more than buying the biggest unit on offer.
Frequently asked questions
Roughly £3,000 to £6,000 installed for a usable 5 to 10 kWh battery, depending on brand, size and whether it's fitted alongside new panels or retrofitted.
On solar self-use alone, often only just inside the warranty. On a time-of-use tariff with cheap overnight charging, the payback is usually much faster.
Typically warranted for about 10 years or 6,000 cycles, retaining around 70 to 80% of capacity by the end. Many keep working beyond that at reduced capacity.
Yes. On a time-of-use tariff you can charge it from cheap overnight electricity and use it during expensive peak hours, which is a big part of the financial case.
No. Panels work and pay back on their own. A battery is an optional add-on that suits some usage patterns and tariffs more than others.