Combining a heat pump with solar panels is one of the most effective ways to cut your energy bills and reduce your dependence on the grid. In the right setup, you can run your heating largely on free electricity you’ve generated yourself. This guide explains how to make it work in practice.
Heat pumps run on electricity. Solar panels produce electricity. That’s the simple version. The more nuanced picture is that heat pumps are most efficient when run at low temperatures over long periods — exactly the kind of steady background load that solar generation suits well, especially in spring and autumn when the sun is out but heating demand is still significant.
A typical air source heat pump uses between 2,000 and 4,000 kWh of electricity per year for an average UK semi-detached home. A standard 4 kWp solar system generates roughly 3,400 kWh per year in the UK. The overlap is substantial, particularly if you run your heat pump during daylight hours.
The key question is how much solar generation you need to meaningfully offset your heat pump’s running costs. As a rule of thumb:
Don’t try to size solar to cover 100% of annual heat pump consumption — it’s neither practical nor cost-effective. Instead, aim for 50–70% solar coverage, supplemented by a good electricity tariff for the rest.
The biggest challenge with solar and heat pumps is timing. Solar generates most electricity between 10am and 3pm, but heating demand often peaks in the morning and evening. A home battery resolves this mismatch by storing surplus solar generation for use at night or early morning.
For a heat pump household, a battery capacity of 5–10 kWh is typically the sweet spot — large enough to carry evening heating loads, small enough to fully charge and discharge daily. Check out the best home battery storage systems UK to compare current options including the Tesla Powerwall 3, GivEnergy, and Solis systems.
With a battery in place, a well-optimised system can achieve 70–80% self-consumption of solar generation, compared to just 30–40% without one.
The numbers vary, but a realistic estimate for a UK heat pump home with 4 kWp solar and a 10 kWh battery:
Combined with a well-priced electricity tariff, total heat pump running costs can fall to under £500/year for many households — a substantial improvement over gas. See our full breakdown of heat pump running costs in the UK to model your own numbers.
Octopus Energy has built products specifically for solar + heat pump households:
If you’re on a standard tariff, switching to one of these can save a further £150–300 per year on top of your solar savings.
A household in Wiltshire with a 2016-build 4-bed detached home installed a 6 kWp Sunsynk solar system, 9.5 kWh battery, and an 8.5 kW Vaillant arotherm+ in 2024. Their annual electricity bill for heating dropped from ~£1,100 (on the heat pump alone) to under £400 after solar and battery were added. They estimate a full payback on the solar and battery in 7 years, faster than solar alone because of the high self-consumption from the heat pump.
A terrace in Leeds with 3.6 kWp solar and no battery saw more modest savings — around £280/year — but found the combination still worthwhile when combined with Cosy Octopus.
Yes, in most cases — especially if you’re installing a heat pump from scratch and can plan the solar system at the same time. The two technologies amplify each other’s value: the heat pump gives you a large, flexible electricity load to absorb solar generation, and solar cuts the running cost of the heat pump significantly. For most UK homeowners, the combination is now the single most effective energy upgrade available.
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