The short answer
Without a battery, you use solar electricity as it is generated and export the surplus to the grid for payment under the Smart Export Guarantee (SEG). The catch is that solar peaks at midday when many homes use little, so a lot is exported cheaply and then re-imported expensively in the evening. A battery stores that daytime surplus to use after dark, raising your self-consumption from often around 30–50% to 60–80% or more and cutting expensive evening imports. The downside is the upfront cost and a longer payback on the battery itself. A battery also enables smart tariffs (charging cheaply overnight). It is worth it if your evening use is high, your export rate is low relative to your import rate, or you want resilience and tariff flexibility; less so if you use most electricity by day or your export rate is generous.
Almost every solar quote now offers a battery, but it is a separate decision with its own economics. Panels save money on their own; a battery saves more but costs more. Here is how to judge whether the battery earns its place.
Battery vs no battery
- Self-use, no batteryOften ~30–50%
- Self-use, with batteryOften ~60–80%+
- Battery main benefitUse solar after dark
- Battery downsideCost, longer payback
- Battery bonusCheap overnight tariffs
What a battery changes
Solar generation peaks around the middle of the day. If no one is home to use it, much of that electricity is exported to the grid, paid at the SEG export rate, and then in the evening you import electricity at the higher import rate to cook, heat and light the home. The gap between what you are paid to export and what you pay to import is where a battery earns its keep.
A battery stores the midday surplus and releases it in the evening, so you use far more of your own generation instead of selling low and buying high. This raises self-consumption — the share of your solar you use yourself — from often around 30 to 50% without a battery to commonly 60 to 80% or more with one. Higher self-consumption means lower bills, because every stored kilowatt-hour offsets an expensive import rather than a cheap export.
| Factor | Solar without battery | Solar with battery |
|---|---|---|
| Daytime surplus | Exported (SEG rate) | Stored for later |
| Evening use | Imported (full price) | From battery |
| Typical self-consumption | ~30–50% | ~60–80%+ |
| Upfront cost | Lower | Higher |
| Payback | Faster (panels only) | Slower (battery adds cost) |
| Smart tariff charging | No | Yes (cheap overnight) |
| Power cut backup | No (unless designed) | Possible with backup feature |
Indicative comparison for guidance. Sources: Energy Saving Trust; Ofgem (SEG).
The economics and tariffs
Panels alone usually have the shorter payback because they are cheaper and every unit you use directly saves the full import price. Adding a battery increases the upfront cost, and the battery pays back on the difference between import and export rates — the more expensive your evening electricity and the lower your export rate, the better the battery's case. Where export rates are generous relative to import rates, exporting surplus may be nearly as good as storing it, weakening the battery's argument.
Batteries also open up smart time-of-use tariffs: charge the battery from the grid during cheap overnight windows and use it during expensive peak hours, on top of storing solar. This can meaningfully improve the economics and is a reason some homeowners add a battery even with modest solar. Consider the battery and tariff together, since the right tariff can shorten the battery's payback.
When to add a battery, and when not to
A battery is most worthwhile when your evening and overnight electricity use is high (so there is plenty of stored energy to displace expensive imports), when your import rate is high relative to your export rate, when you want to exploit cheap overnight smart tariffs, or when you value some backup during power cuts (only with a battery designed for that). Households out during the day, who would otherwise export most of their generation, often gain the most from storing it instead.
Going without a battery can make more sense if you use most of your electricity during daylight hours (home workers, daytime EV charging), if you have a generous export tariff that pays well for surplus, or if you want the lowest upfront cost and fastest payback from panels alone. You can also fit panels now and add a battery later — an AC-coupled battery retrofits to existing solar — so the decision is not permanent.
Size any battery to your evening and overnight use rather than the largest available, and get an MCS-certified installer to model both options on your actual consumption and tariff. For many homes a moderate battery captures most of the benefit; for others, panels alone are the better value. The right answer depends on when you use electricity and the gap between your import and export rates.
Frequently asked questions
Is a solar battery worth it in the UK?
It depends on your usage and tariffs. A battery is worth it if your evening use is high, your import rate is well above your export rate, or you want to use cheap overnight tariffs. It raises self-consumption from often 30–50% to 60–80% or more. It is less worthwhile if you use most electricity by day or have a generous export rate.
Can I add a battery to solar panels later?
Yes. An AC-coupled battery has its own inverter and connects on the household AC side, making it straightforward to retrofit to an existing solar system. So you can install panels now for the lowest upfront cost and faster payback, then add storage later if your usage or tariffs make a battery worthwhile.
How much does a battery improve solar savings?
By raising self-consumption — the share of your solar you use yourself — typically from around 30–50% without a battery to 60–80% or more with one. Each stored unit offsets an expensive evening import instead of being exported cheaply. The exact saving depends on your evening use and the gap between your import and export rates.
Sources & further reading
Figures on this page are typical UK ranges drawn from published sources and depend on your specific home. They are guidance, not a quotation or guaranteed saving.