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Solar battery storage UK: cost, payback and is it worth it in 2026?
Solar battery storage in the UK costs £3,000–£6,000 added to solar. For most homes it's worth it if your SEG rate is below 10p/kWh — here's the honest maths.
A solar battery captures the electricity your panels generate during the day that you’d otherwise export to the grid at a low SEG rate. Instead of earning 5–15p per kWh exported, you store it and use it in the evening at the full import rate of ~27p/kWh. That 12–22p/kWh gap is the entire economic argument for a solar battery in the UK.
Whether that gap is big enough to justify a £3,000–£6,000 battery depends heavily on your SEG rate, your household’s daily consumption pattern, and whether you also have an EV.
What solar battery storage costs in the UK (2026)
Installed costs for a battery added to an existing or new solar system:
| Battery size | Typical brands | Installed cost |
|---|---|---|
| 5 kWh | Givenergy, Fox ESS, Growatt | £3,000–£4,000 |
| 10 kWh | Givenergy, Fox ESS, Pylontech | £4,500–£5,500 |
| 13.5 kWh | Tesla Powerwall 3 | £8,000–£9,000 |
| 16 kWh | Givenergy 3-phase, SolarEdge | £6,500–£8,000 |
VAT is zero-rated on batteries installed at the same time as solar panels (or as a retrofit to an existing solar system from the same installer visit). A standalone battery fitted by a different company at a later date may attract 20% VAT — worth timing your installation to avoid.
The Powerwall premium is real but rarely justified on economics alone. A mid-range LiFePO4 unit from Givenergy or Fox ESS delivers almost identical savings at 40–60% of the cost. You’re paying for Tesla’s app, warranty brand, and backup-power capability — not for meaningfully better kWh economics.
How much does a solar battery actually save?
The saving comes from replacing exported kWh (worth your SEG rate) with self-consumed kWh (worth your import rate). A 5 kWh battery on a typical 4 kWp system lifts self-consumption from ~35% to ~60% of annual generation.
For a system generating 3,600 kWh/year:
- Without battery: exports ~2,340 kWh @ 15p SEG = £351 export income + uses 1,260 kWh @ 27p = £340 saving = £691 total
- With 5 kWh battery: exports ~1,440 kWh @ 15p = £216 + uses 2,160 kWh @ 27p = £583 = £799 total
- Extra saving from battery: ~£108/yr at 15p SEG
Now run it with a 5p SEG rate (common on low-end tariffs):
- Without battery: exports ~2,340 kWh @ 5p = £117 + uses 1,260 kWh @ 27p = £340 = £457 total
- With battery: exports ~1,440 kWh @ 5p = £72 + uses 2,160 kWh @ 27p = £583 = £655 total
- Extra saving from battery: ~£198/yr at 5p SEG
The lower your SEG rate, the more a battery is worth. This is the number most solar quotes gloss over.
Solar battery payback: realistic UK timelines
On a £3,500 battery install:
| SEG rate | Extra annual saving | Payback |
|---|---|---|
| 15p/kWh | ~£100–120/yr | 28–35 yrs |
| 10p/kWh | ~£140–160/yr | 22–25 yrs |
| 5p/kWh | ~£190–220/yr | 16–18 yrs |
| 5p + EV overnight charging | ~£350–450/yr | 8–10 yrs |
The EV row is the real game-changer. An EV charging overnight on off-peak electricity (8–12p/kWh via Octopus Go or Intelligent) saves £300–500/yr on top of the solar battery saving, and that saving is unlocked by the battery cycling cheap-rate electricity into the evening peak. The combined payback on a battery + EV charger setup can be 8–10 years even in the UK’s cloudy north.
When solar battery storage is not worth it
- High SEG rate (12p+) and no EV. If Octopus is paying you 15p to export, you’re already getting well-compensated. A battery adds little unless you have large evening demand.
- Small solar system (under 3 kWp). Not enough surplus generation to fill the battery reliably. A 5 kWh battery cycling at 60% capacity won’t hit the saving numbers above.
- New solar, planning to move within 5 years. A battery adds some resale value but payback is unlikely before a short-horizon sale.
- Budget is tight. Solar alone is the better first investment. Add the battery later once the solar has started paying and your export behaviour is clear.
The right way to size a solar battery
Size for your evening peak consumption, not your total daily use. If your household uses 8 kWh after 4pm, a 5 kWh battery covers most of that. A 10 kWh battery adds maybe £50/yr in extra saving over the 5 kWh unit — the marginal return drops steeply above the household’s actual peak window.
Most UK 3-bed semis are well-served by a 5 kWh battery. Only go to 10 kWh if you have high evening use (heat pump, EV, or multiple occupants with shifted hours) or you want backup power during outages.
Modelling your specific combination
The numbers above use national averages. Your actual payback depends on your postcode yield, household consumption profile, SEG rate, and whether you have or plan an EV. The solar battery and EV combined calculator lets you enter your real numbers and see combined payback for any solar + battery + EV stack.
If you don’t have solar yet, start with the solar panel savings calculator to establish your solar-only payback first, then layer in the battery to see whether it’s worth adding from the start or as a later upgrade.