Eight hundred pounds a year off the heating bill, that is the headline figure from a new UK analysis of heat pumps paired with solar panels and batteries. For a typical three-bed semi using 12,000 kWh of gas and 3,500 kWh of electricity, that saving would cut total annual energy costs by roughly a third. The catch: you need three technologies working together, not just one.
The study, commissioned by a coalition of clean-tech firms and reviewed by academics at the University of Oxford, modelled real-world performance across 100 homes in England and Wales. As reported by The Cool Down, the savings come from shifting electricity use to cheap-rate periods on smart tariffs, typically overnight or midday, and using the battery to run the heat pump when grid prices spike.
How the £800 saving stacks up
The figure assumes a 7 kW air-source heat pump, 4 kW of solar panels, and a 10 kWh battery. On a standard variable tariff, the heat pump alone would add roughly £200 to the annual electricity bill compared with a gas boiler, because electricity costs more per kWh than gas. But solar generation offsets about 40% of that extra demand, and the battery lets the household buy power at 7p/kWh on an off-peak tariff rather than 28p/kWh during peak hours.
Ofgem’s price cap currently sets typical electricity at 24.5p/kWh and gas at 6.2p/kWh. A smart tariff like Octopus Flux or OVO Charge Anytime offers rates as low as 5–8p/kWh for four to six hours a day. The study found that homes with all three technologies and a smart tariff saved an average of £780–£820 annually compared with a gas boiler on a standard tariff.
But the study also noted that homes without solar or battery, just a heat pump on a standard tariff, saw bills rise by £50–£150 a year. The battery is the key that unlocks the saving, not the heat pump alone.
Who qualifies, and who doesn’t
The Boiler Upgrade Scheme (BUS) offers £7,500 off an air-source heat pump, but only for homes with a valid EPC and no outstanding cavity-wall or loft-insulation recommendations. Solar panels and batteries are not covered by BUS, though the 0% VAT on energy-saving materials applies until 2027. A 4 kW solar system typically costs £6,000–£8,000; a 10 kWh battery adds another £4,000–£6,000. Total upfront: £17,500–£21,500 minus the BUS grant, still £10,000–£14,000.
The Energy Saving Trust estimates payback at 8–12 years for the full package, assuming the £800 saving holds and electricity prices do not fall sharply. Homes with south-facing roofs and low shading will see faster returns. Those with north-facing roofs or listed-building restrictions may not get enough solar yield to justify the battery.
What this means for EPC ratings
An EPC rating is calculated on assumed energy costs, not actual usage. A heat pump alone typically lifts a D-rated home to a C. Adding solar panels and a battery can push it to a B, but only if the assessor models the battery as reducing peak-time electricity draw. Many assessors still use a standard occupancy assumption that ignores smart tariffs, so the actual EPC uplift may be smaller than the bill saving.
The government’s proposed reforms to EPC methodology (due in 2025) will factor in time-of-use tariffs and battery storage, which should bring EPC scores closer to real-world savings. Until then, homeowners should ask their assessor explicitly to model a smart tariff and battery in the calculation.
The £800 figure is a best-case scenario from a modelling study, not a guarantee. But it points to a clear direction: heat pumps alone rarely cut bills; heat pumps plus solar plus battery plus a smart tariff can. For homeowners planning a full retrofit, the order matters, solar first, then battery, then heat pump, because the battery needs to be sized to the solar output, and the heat pump should be selected for low-temperature operation to maximise the battery’s range.
Households on standard variable tariffs should check their roof orientation and shading using the Solar Energy Calculator at gov.uk. If the roof works, the next step is to get quotes for a 4–5 kW solar array and a 10 kWh battery from MCS-certified installers. The heat pump can wait until the Boiler Upgrade Scheme reopens in April 2025, when the £7,500 grant will still be available. Act before the end of the 2024–25 financial year to lock in the current VAT exemption on batteries.
Frequently Asked Questions
No. The study found that without a battery, the heat pump and solar combination saved only £100–£200 a year, because most solar generation happens midday while the heat pump runs mainly in the morning and evening. The battery is essential to shift cheap-rate electricity to peak hours.
Yes. The BUS grant of £7,500 is available regardless of whether you already have solar panels, as long as your EPC has no outstanding loft or cavity-wall insulation recommendations and the heat pump is installed by an MCS-certified installer. The grant is deducted from the installer's quote, not paid to you directly.
