UK Power Networks, OVO and tepeo published the findings of the Neat Heat trial on 4 September 2024, reporting that heat batteries can shift peak energy demand for heating to off-peak times by up to 95%1. The trial ran for 18 months until June and installed tepeo's Zero Emission Boiler (ZEB), which uses heat battery technology, in 30 homes across the South East and East of England1.
The headline figure covers a trialist's yearly heating demand. In the coldest weeks of winter, over 90% of demand could still be moved outside peak hours, when demand on the grid is highest1. The trial reported carbon savings of 15,600kg CO2 compared with the same homes using gas boilers1. Installations took on average one to two days, and all trialists opted to continue with the ZEB rather than revert to a fossil fuel boiler1. Participants reported no noticeable change to their heating, with the ZEB providing a similar experience to a traditional boiler but powered entirely by electricity1.
The trial was built around a tariff proposition developed by OVO called a "type of use", giving customers access to a cheaper than standard rate to charge their ZEBs, and customers could also set their ZEBs to charge during the cheapest times of the day1. At launch the project attracted more than 2,000 registrations of interest for the limited spaces available1.
UK Power Networks said heat batteries are ideal for the estimated over 20% of UK homes that lack the space required for low carbon solutions such as heat pumps, or where those solutions could prove difficult to retrofit1.
"Being able to move electricity demand away from peak hours is huge, for both our network and customers."
Luca Grella added that shifting demand away from peak hours would reduce the network upgrades needed to keep up with future demand for green technologies, which would ultimately have been paid for by customers across the country1. Johan du Plessis, CEO of tepeo, said heat batteries working in tandem with dynamic tariffs would enable millions of homes currently unable to switch to low-carbon solutions to join the green transition1. Grainne Regan, head of Heat at OVO, described the ability to decouple electricity consumption from heating as an essential part of decarbonising home heating, and referred to a joint mission to decarbonise the UK energy grid by 20351.
Why it matters for households
The reported result is about when heating uses electricity, not how much. A heat battery stores heat so a home can draw power outside the most expensive hours and release heat on demand, which is the mechanism behind the 95% figure1. For a household, that separates the cost of running heating from the times of day when heating is actually wanted, provided the home is on a tariff that prices off-peak electricity lower1.
The trial points to a group of homes that other electrification routes may not reach. UK Power Networks estimates over 20% of UK homes lack the space for heat pumps or would be difficult to retrofit, and positions heat batteries as suited to those properties1. The 30 homes involved are a small sample, and the findings cover one winter and a year and a half of operation; no costs to households, installation prices or running-cost figures were reported1. Wider deployment would depend on network capacity, tariff design and the availability of installers, none of which the findings quantify1.
What happens next
UK Power Networks, OVO and tepeo held an Installer webinar on 5 September 2024 to discuss the findings in more detail1. The full Neat Heat trial report is published by UK Power Networks1. No further trial phases, product dates or policy decisions have been reported1.