Are solar batteries worth it in the UK?

The core idea

UK solar has a timing problem: panels generate most at midday, but households use most in the morning and evening. Without storage, that midday surplus is exported for your SEG rate, often ~13p, while you buy it back at ~27p a few hours later. A battery closes that gap: it stores the surplus and releases it when you need it, so those units save the full import rate instead of earning the low export rate.

The value, roughly

Each unit a battery shifts from "export then re-buy" to "store then use" is worth roughly the difference between your import and export rates, about 27p − 13p ≈ 14p per kWh. A typical 5kWh battery cycling once a day moves ~1,500-1,800 kWh a year, so the saving lands around £200-£300 a year. Against a fitted cost of roughly £3,000-£5,000, that's a payback in the region of 10-20 years, often close to the battery's warrantied life, which is why batteries are a finer call than the panels themselves.

What tips it in a battery's favour

• An agile / time-of-use tariff. This is the big one. Charge the battery from the grid when import is cheap (overnight, sometimes under 10p) and export at peak (25-30p), on top of storing your own solar. This can double a battery's value versus a flat tariff.
• Low daytime occupancy. If nobody's home to use midday solar, a battery captures what would otherwise be exported cheaply.
• A big gap between import and export rates. The wider the spread, the more each stored unit is worth.
• An EV or heat pump. More flexible load to soak up stored or cheap-rate energy.

What works against it

• A high SEG export rate. If you already get 20p+ for exports, the gain from self-consuming instead is smaller.
• High daytime usage. If you already use most of your solar as it's generated, there's less surplus for a battery to store.
• Upfront cost sensitivity. A battery roughly doubles the system price; the panels alone usually pay back faster.

Bottom line

Get the panels first, they're the stronger investment. Add a battery if you're on (or willing to switch to) an agile tariff, you're out during the day, or you value backup and energy independence beyond the pure payback. If you just want the fastest return, panels on a good flat SEG tariff usually win.

Our calculator models a panels-only system with typical UK self-consumption, so it gives you the baseline, then you can weigh a battery on top of that using the numbers above.