Heat Pump and Solar in 2026: How Well Do They Pair?

The pairing in plain English

A heat pump uses electricity to extract heat from the air or ground and pump it into your home. A solar PV system generates electricity from sunlight. The pairing sounds obvious but the seasonal mismatch is significant: solar generates most in summer when you need least heat; heat pumps draw most in winter when solar generates least. The pairing still pays off — but not for the reason most marketing brochures suggest.

How much solar covers heat pump demand

A typical UK 3-bed semi with a 7kW heat pump draws around 4,500 kWh/year of electricity for space heating and hot water. A typical 4kWp solar system generates around 3,800 kWh/year. Naive maths suggests solar covers 84% of heat pump demand. The reality: when you overlay generation and consumption month-by-month, solar covers around 22-28% of heat pump electricity because the timing barely overlaps.

Why the pairing still pays

The financial case for solar+heat pump rests on the heat pump replacing gas (or oil), not on solar powering the heat pump. A heat pump moves heat at 280-320% efficiency versus a gas boiler at 85-93%. On a kWh-of-heat basis a heat pump on a 28p/kWh import is roughly equivalent to a gas boiler on 9p/kWh — which is well above current UK gas prices. So the heat pump pays back against gas, and the solar pays back against grid power. They are two independent investments that happen to share an electrical control system.

Sizing recommendations

If you have a heat pump (or are installing one), we recommend oversizing the solar to 6.4-8.6kWp rather than 4.3kWp. The extra panels do not pay back as solar alone, but they do feed the larger overall electrical demand of a heat-pump home — lifting overall household self-consumption to 60%+ rather than the typical 38%.

Best Octopus tariff for the combination

Cosy Octopus (mentioned in our Octopus tariff comparison) is purpose-built for heat pumps with three distinct windows — early-morning charge, midday solar/cheap, and a peak avoidance window 16:00-19:00. For solar+heat pump homes, Cosy is almost always the right tariff choice.