Plug-in batteries—portable energy storage units that plug into standard wall sockets—could significantly expand access to home battery technology in Great Britain, particularly for renters, flat dwellers, and low-income households currently excluded from traditional systems.
According to Regen, a plug-in battery charges during off-peak periods on time-of-use tariffs and discharges when electricity is more expensive, allowing households to reduce their bills. Unlike professionally installed home battery systems that require qualified electricians and structural modifications, plug-in batteries function like standard household appliances. This removes installation costs, which typically account for £1,000 to £1,500 of a traditional system’s price.
Regen’s analysis shows that a 3 kWh plug-in battery paired with the Octopus Go time-of-use tariff could pay back in approximately 2.5 years, with 10-year savings reaching up to £2,400 for high-energy households. Households that shift demand to off-peak periods and use larger or multiple batteries could reduce costs by 30-34% over a decade, though this assumes no changes to electricity tariffs.
The potential beneficiaries are substantial. Great Britain has approximately 9 million rented households, 6 million flat and apartment households, and 11.4 million low-income households—collectively representing 12 to 14 million homes, or close to half of all households in the country. These groups have been largely unable to install fixed battery systems due to cost, lack of permission, or insufficient space.
The UK government announced in March that regulation changes would make plug-in solar panels available “within months” as part of its energy security response. Plug-in solar has been available for nearly a decade in Germany, where over a million systems are now installed. Systems are sold off-the-shelf in mainland Europe at retailers including Ikea and Lidl, but have not been legal in Great Britain until now.
However, the government announcement notably excluded plug-in batteries. The primary barrier is existing electrical safety regulation. BS 7671, which governs household electrical installations in the UK, does not currently permit appliances to discharge power back into household circuits, as wiring regulations were designed only for one-directional power flow.
Beyond household savings, rapid uptake of plug-in batteries could deliver system-wide benefits. Under a rapid uptake scenario, total discharge capacity could reach nearly 1 gigawatt by 2030 with storage capacity over 4 GWh. When paired with plug-in solar panels, batteries could dampen voltage rise issues caused by correlated generation during sunny periods while enabling households to capture higher value by using stored solar power later in the day.
Key facts
- Plug-in batteries could reduce household electricity bills by up to £2,400 over 10 years when paired with time-of-use tariffs
- Installation costs of £1,000 to £1,500 are eliminated because plug-in batteries require no professional installation
- 12 to 14 million UK households—nearly half of all homes—are currently excluded from traditional battery systems due to renting status, flat dwelling, or low income
- Plug-in solar panels have been available in Germany for nearly a decade with over 1 million systems installed
- BS 7671 electrical safety regulations currently prohibit appliances from discharging power back into household circuits