Heat Pump and Solar PV: The Whole-Home Energy System
A heat pump plus solar PV can cut your annual energy costs by £680-930 compared to a gas boiler on a standard tariff. This whole-home energy system combines free daytime solar electricity with cheap overnight tariff rates, delivering heating costs below £400 per year for many UK homes.
This guide covers the economics of combining both technologies, the grants available, sizing advice, and how to maximise the benefit from your integrated heat pump and solar panel system.
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The Combined Economics
| Scenario | Annual Heating + Hot Water Cost | Annual Saving vs Gas Boiler |
|---|---|---|
| Gas boiler (standard tariff) | £850-1,100 | — |
| Heat pump (standard tariff) | £980 | £0-120 (marginal) |
| Heat pump + Octopus Cosy | £600 | £250-500 |
| Heat pump + Cosy + 4kW solar | £350-400 | £450-700 |
Gas boiler assumes 12,000 kWh heat demand at 90% efficiency and 6.5p/kWh gas rate. Solar export income adds £100-150.
Grants and Funding
Heat Pump Grant
Solar VAT
0% VAT on residential solar
Net System Cost
£5,500-13,500 after grant
Combined Payback
7-10 years
System Sizing
- Heat pump: Size based on your home's heat loss calculation — typically 5-12 kW for most UK homes. Your MCS installer will specify this
- Solar PV: A 4kW system (10-12 panels) is ideal for most 3-4 bed homes with a heat pump. See the Home Solar Guide for detailed sizing
- Hot water cylinder: 200-300L recommended — acts as thermal storage for surplus solar
Maximising the Combination
- Use a solar diverter: Automatically diverts surplus solar to your hot water cylinder via the heat pump
- Schedule daytime hot water: Run the heat pump for hot water during peak solar hours
- Use Octopus Cosy for overnight: Solar covers daytime; Cosy covers overnight heating at 10p/kWh
- Monitor with smart meter: Track self-consumption and identify optimisation opportunities
- Consider export tariffs: Earn income from surplus solar you cannot use
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Frequently Asked Questions
How much does a combined heat pump and solar PV system cost?
A heat pump (£8,000-14,000) plus 4kW solar (£5,000-7,000) totals £13,000-21,000. After the BUS grant (£7,500), net cost is £5,500-13,500 with 7-10 year payback.
What are the annual savings from solar + heat pump?
Combined savings of £680-930 per year compared to a gas boiler. See our full cost-reduction guide.
Should I install both at the same time?
Not essential. Getting the heat pump first (with the £7,500 grant) and adding solar later works fine.
Do I need a battery for the combined system?
Not essential currently. A battery adds £5,000-10,000 with marginal additional savings. Your hot water cylinder provides free thermal storage.
The Whole-Home Energy Future
The combination of heat pump, solar PV, and smart tariffs represents the future of UK home energy. The Boiler Upgrade Scheme and zero-VAT solar make this combination increasingly affordable. With proper insulation, the right electricity tariff, and smart controls, UK homes can achieve near-zero-carbon heating at costs below gas — fulfilling the promise of the heat pump transition.