UK thermal storage subsidy proposed, new heat battery standard in development

The UK government has proposed a new grant for domestic thermal storage in a bid to accelerate the decarbonization of home heating. Grants would be available through the Boiler Upgrade Scheme (BUS), which currently offers a GBP 7,500 ($10,000) subsidy for air-source heat pumps in England and Wales.

BUS grants have been the key driver behind accelerated air-source heat pump deployment in the United Kingdom. The UK government’s Department for Energy Security and Net Zero (DESNZ) said it had received 4,028 BUS applications in March 2025 – up 88% on the same month in 2024. It is proposing to expand the subsidy to include more technology types such as heat batteries and air-to-air heat pumps, following consultation with industry stakeholders.

Heat batteries work by using electricity to heat a thermal storage medium which then heats water via a heat exchanger to feed a central heating system. The UK government’s consultation describes heat batteries as a “promising technology” due to their ability to take advantage of time-of-use tariffs. When electricity is cheap, the heat battery can heat the thermal storage which can feed the property’s central heating system or a sanitary hot water system.  

However, DESNZ’s consultation paper notes that the impact heat batteries can have on the electricity grid is “highly contingent” on correctly sizing it for the property, charging patterns, and the availability of suitable tariffs. To ensure any heat batteries installed as part of a government grant scheme provide optimal outcomes, certification body MCS has established a working group to create a new MCS standard for the installation of heat batteries. Certified installations are a requirement to secure the subsidy for air-source heat pumps under the scheme’s current rules.  

Tom Lowe, founding director of Thermal Storage UK, praised the proposal. “We warmly welcome the government looking to expand the technologies included in the Boiler Upgrade Scheme. Electrifying home heating requires either super-efficient heat pumps or highly flexible heat batteries,” said Lowe.

Ned Hammond, deputy director for customers at trade association Energy UK, said expanding eligibility for BUS grants would give families greater choice. “More flexibility in the way customers can pay for these technologies will also help make efficient and smart heating systems, such as heat pumps, heat batteries and heat networks, available to even more customers who are struggling with high energy bills and looking for an alternative to costly gas boilers.”   

The announcement follows the launch of UK government research activity into the performance of heat batteries in UK housing stock as part of its Homes for Net zero project. The research is due to conclude later in 2025. The DESNZ consultation on expanding the scope its BUS subsidy is open to submissions until June 11, 2025.