The Department for Energy Security and Net Zero (DESNZ) is consulting on a discount scheme for home heat batteries, devices that store electricity as heat during off-peak hours and release it when needed. The move, as reported by Solar Power Portal, could represent the first targeted subsidy for a technology that has so far sat in the shadow of heat pumps and solar thermal.
Who qualifies, and who doesn’t
DESNZ has not published full eligibility criteria, but the consultation document suggests the discount would apply to heat batteries that store at least 6 kWh of thermal energy and are installed in homes with a gas or oil boiler being replaced. The proposed discount is between £500 and £1,000 per unit, based on early estimates seen by industry insiders. That would bring a typical 10 kWh heat battery, currently priced at £2,500–£3,500 installed, closer to £1,500–£2,500.
But the catch is that heat batteries work best in homes with good insulation. A property with an EPC rating below D will leak heat faster than the battery can supply it, making the device inefficient and potentially increasing overall energy use. Ofgem data suggests that 40% of UK homes are rated D or below, meaning millions of households would need to upgrade loft and cavity wall insulation first, at a cost of £1,000–£3,000, before the heat battery becomes viable.
What it costs a typical 3-bed semi
For a typical 3-bed semi with an EPC rating of C and annual heating demand of 12,000 kWh, a heat battery could reduce heating bills by roughly 20–30% compared with a gas boiler, assuming the household can access an off-peak electricity tariff such as Economy 7 or a time-of-use plan. At current price cap rates, around 24p/kWh peak and 12p/kWh off-peak, the saving would be about £150–£250 per year. That means the payback period, even with the proposed discount, would be 6–10 years, depending on the battery size and installation cost.
Yet this is less attractive than a heat pump in the same home, which can cut heating bills by 30–50% and currently attracts a £7,500 grant under the Boiler Upgrade Scheme. The heat battery discount is smaller, and the technology is less efficient than a heat pump, though it is simpler to install, requires no outdoor unit, and works with existing radiators.
EPC impact, modest at best
Heat batteries do not directly improve a home’s fabric energy efficiency, so they will not lift an EPC rating on their own. Energy Performance Certificates measure heat loss through walls, windows, and roofs, not the heating system’s efficiency. A heat battery can improve the heating system’s efficiency score slightly, typically by 5–10 points on the 100-point scale, but that is rarely enough to move a home from D to C. The government’s own modelling, seen by the Energy Saving Trust, suggests that a heat battery alone would improve an average D-rated home by only 3–5 points.
For homeowners aiming to sell or rent, where an EPC rating of C or above is increasingly required, the heat battery discount is a distraction unless paired with insulation and glazing upgrades. The real prize for most households remains reducing heat demand first, then switching to a low-carbon heat source.
Households on standard variable tariffs can monitor the consultation via gov.uk. The consultation closes on 31 March 2025. If the scheme launches, it will open for applications from autumn 2025, with discounts paid directly to installers.
Frequently Asked Questions
No. The proposed DESNZ discount is for homes replacing a gas or oil boiler with a heat battery as the primary heating source. Homes with existing heat pumps are not eligible.
For off-grid homes using oil or LPG, a heat battery can be cheaper to install than a heat pump, roughly £2,000–£3,000 versus £9,000–£12,000 after grants. But running costs depend on electricity tariffs; off-grid homes without access to cheap off-peak rates may see higher bills.
