A battery transforms solar from a daytime-only technology to a 24-hour one — increasing typical self-consumption from around 30% to over 80%. Is the cost justified for your property?
For most homes with solar panels — yes, especially with WH:LG funding or a time-of-use tariff. Without a battery, most homes self-consume only about 30% of solar generation. The rest is exported to the grid at 3–7p/kWh. A battery stores that surplus for evening use, when grid electricity costs 22–28p/kWh.
| Scenario | Annual saving | Battery cost | Payback |
|---|---|---|---|
| 3-bed home, solar + 10kWh battery, ToU tariff | ~£750/yr | £4,500–£6,000 | 6–8 years |
| 3-bed home, solar + 5kWh battery, standard tariff | ~£500/yr | £2,800–£4,000 | 6–8 years |
| 4-bed home, solar + 10kWh + EV | ~£1,100/yr | £5,000–£7,000 | 5–6 years |
| Standalone battery (no solar), ToU tariff | ~£300/yr | £3,500–£5,000 | 12–17 years |
If grant funding covers the battery fully, the payback question is simple — you get the savings at zero upfront cost.
Solar + battery at 0% VAT, with 70–90% self-consumption, transforms the economics of solar significantly.
Tariffs like Octopus Go or Agile offer sub-10p/kWh overnight. A battery charges cheaply and discharges at peak times when rates are 3–5x higher.
If nobody is home daytime, solar generation goes to waste without a battery. A 10kWh system can store a full day’s generation for evening use.
You are on a flat-rate tariff with no plans to switch. You have no solar and cannot pair the battery with panels. You are not eligible for grant funding. Battery technology and prices continue to evolve — waiting 2–3 years could mean lower costs if a grant is not available.
For most homes with solar, yes — a battery increases self-consumption from ~30% to 70–90%. The case is strongest with WH:LG funding or a time-of-use tariff.
Combined solar + battery payback is typically 4–8 years. A standalone battery is 8–14 years depending on energy use and tariff.
Typical annual savings for a 3-bed home with solar + battery are £500–£900. Higher with an EV or heat pump.
A battery installed alongside solar qualifies for 0% VAT until 31 March 2027ly. A standalone battery is subject to 20% VAT.