Calculate combined savings when pairing solar panels with a heat pump
| Item | Cost | Annual Benefit |
|---|
Heat pumps use most electricity in winter when solar generation is lowest. Expect only 15-25% of winter heat pump demand to be met by solar.
Adding a battery can increase the solar-to-heat-pump percentage, but adds £4,000-8,000 to system cost.
Heat pump efficiency (COP) varies with outside temperature. Winter COP may be 2.5, summer COP can exceed 4.0.
Enter your home details, choose a heat pump type, and specify your solar system size. The calculator estimates your combined annual savings, payback period, and carbon reductions compared to your current heating system. Results account for the seasonal mismatch between solar generation and heating demand.
Solar panels and heat pumps are two of the most effective ways to reduce home energy costs and carbon emissions. When combined, they create a powerful synergy — your solar electricity can power your heat pump, delivering virtually free heating.
Generate free electricity from sunlight. A typical 4-5kWp system produces 3,500-4,500 kWh per year — enough to significantly offset heat pump running costs and power your home.
Extract heat from outside air (or ground) and deliver 3-4x more heat energy than the electricity they consume. A COP of 3.0 means 1kWh electricity produces 3kWh of heat.
Solar-powered heat pumps can reduce heating costs by 60-80% compared to gas boilers, while cutting your carbon footprint to near zero for home heating and electricity.
Savings depend on your current heating system, home size, insulation quality, and energy prices. Here’s what typical UK households can expect:
| Current Heating | Typical Annual Cost | With Heat Pump Only | With Solar + Heat Pump |
|---|---|---|---|
| Gas Boiler | £1,200 – £1,800 | £900 – £1,400 | £400 – £800 |
| Oil Boiler | £1,500 – £2,500 | £900 – £1,400 | £400 – £800 |
| LPG Boiler | £1,800 – £2,800 | £900 – £1,400 | £400 – £800 |
| Electric Heating | £2,000 – £3,500 | £700 – £1,200 | £300 – £600 |
| Storage Heaters | £1,500 – £2,500 | £700 – £1,200 | £300 – £600 |
Based on average 3-bed semi-detached house with moderate insulation. Actual savings vary significantly based on property size, insulation quality, and usage patterns.
The biggest challenge with solar + heat pump systems is timing: heat pumps work hardest in winter when solar generation is lowest, and solar produces most in summer when heating demand is minimal.
What this means in practice: Typically only 25-35% of your heat pump’s annual electricity consumption can be directly powered by solar. The rest comes from the grid. However, excess summer solar exports earn SEG payments, partially offsetting winter grid costs.
Don’t expect solar to fully power your heat pump through winter. In December and January, you might generate only 5-15% of what your heat pump needs due to short days and low sun.
The real benefit comes from spring/autumn shoulder seasons, summer hot water heating, and offsetting your general household electricity use year-round.
| Factor | Air Source (ASHP) | Ground Source (GSHP) |
|---|---|---|
| Efficiency (COP) | 2.8 – 3.5 average | 3.5 – 4.5 average |
| Winter Performance | COP drops to 2.0-2.5 in cold spells | Stable COP year-round |
| Installation | Simpler, 2-3 days typical | Requires ground works, 1-2 weeks |
| Space Required | External unit + 1m clearance | Garden for trenches or borehole |
| Noise | Fan noise (40-50dB typical) | Silent operation |
| Best For | Most homes, budget-conscious | Larger properties, max efficiency |
The right combination depends on your home’s heat demand (determined by size, insulation, and location) and your electricity consumption patterns.
| Property Type | Heat Pump Size | Recommended Solar | Cost After Grant |
|---|---|---|---|
| 1-2 Bed Flat | 4-6 kW | 2-3 kWp | £8,000 – £12,000 |
| 2-3 Bed Terrace | 6-8 kW | 3-4 kWp | £10,000 – £15,000 |
| 3 Bed Semi | 8-10 kW | 4-5 kWp | £12,000 – £18,000 |
| 4 Bed Detached | 10-14 kW | 5-6 kWp | £15,000 – £22,000 |
| 5+ Bed / Poorly Insulated | 12-17 kW | 6-8 kWp | £18,000 – £28,000 |
Costs assume ASHP with BUS grant deducted. Add £8,000-15,000 for ground source instead of air source.
Before installing a heat pump, consider improving your home’s insulation. Better insulation means a smaller (cheaper) heat pump, lower running costs, and more of your solar can cover the reduced demand. A well-insulated home might need a 6kW heat pump instead of 10kW — saving thousands on purchase and running costs over the system’s lifetime.
MCS-certified installer surveys your property, calculates heat loss, assesses radiator sizes, and checks electrical capacity. This determines heat pump size and any upgrades needed.
Installer designs the combined system — heat pump sizing, solar array layout, electrical requirements, and any radiator upgrades or underfloor heating considerations.
Apply for the Boiler Upgrade Scheme (BUS) grant of £7,500 through your installer. Must be done before installation begins. Approval typically takes 2-4 weeks.
Solar installation: 1-2 days. Heat pump installation: 2-5 days depending on complexity. Can be done together or separately. Your old boiler is typically removed on day 1 of heat pump install.
Systems tested, heating balanced, controls explained. You receive MCS certificates, warranty documents, and guidance on optimising your new system.
A home battery stores excess daytime solar for evening use or overnight heat pump operation. However, it adds significant cost and the economics aren’t always favourable:
Solar → Heat Pump: 45-55%
Store daytime solar for evening and overnight heating. Adds £4,000-8,000 for a 5-10kWh solar battery. Best if you have significant excess summer solar and want to maximise self-consumption.
Solar → Heat Pump: 25-35%
Still delivers significant savings. Export surplus to grid for SEG payments. Lower upfront cost means faster payback. Consider adding a battery later as prices continue to fall.
Our recommendation: For most households, start without a battery. The payback on batteries for heat pump systems is typically 10-15 years. Invest in a larger solar array or better insulation instead — both typically offer better returns on investment.