Heat Pump and Solar PV: The Whole-Home Energy System
A heat pump cuts your carbon emissions and delivers efficient heating. Solar PV panels generate free electricity from your roof. Put them together and you have something genuinely transformative — a whole-home energy system that slashes your bills, protects you from energy price rises, and could make your home virtually carbon-neutral for heating and hot water.
This is not theoretical. Thousands of UK homeowners are now running both technologies side by side, and the economics have never been better. With the Boiler Upgrade Scheme covering £7,500 towards a heat pump and separate grants available for solar, the combined upfront cost is far more manageable than most people assume. Here is how the whole-home energy system works, what it costs, and whether it makes sense for your property.
Why Heat Pumps and Solar PV Are Natural Partners
The logic is beautifully simple. A heat pump runs on electricity. Solar PV generates electricity. Every kilowatt-hour your panels produce that your heat pump consumes is a kilowatt-hour you do not buy from the grid at 24p or more.
But the partnership goes deeper than that. Heat pumps use most electricity during the day — particularly for hot water heating, which is typically scheduled for mid-morning or early afternoon. This coincides neatly with peak solar generation. A well-designed system can use solar electricity directly to power the heat pump during its highest-demand periods, dramatically reducing grid consumption.
The multiplier effect
Here is what makes this combination so powerful. When your heat pump uses a kilowatt-hour of solar electricity, it does not just save you 24p (the cost of buying that unit from the grid). Thanks to the heat pump's coefficient of performance (COP), that single kilowatt-hour of electricity produces 3 to 4 kilowatt-hours of heat. You are effectively getting 3-4 kWh of heating from free solar electricity.
Compare that to exporting the same unit to the grid, where you would receive roughly 4-15p depending on your export tariff. Using solar electricity to power your heat pump is worth three to six times more than exporting it.
How the Combined System Works in Practice
A typical UK whole-home renewable energy system consists of:
- Solar PV array: Usually 3-4 kWp (8-10 panels) on a south or south-east/south-west facing roof
- Air source heat pump: Sized to your home's heat loss calculation, typically 5-12 kW
- Hot water cylinder: 200-300 litres, heated by the heat pump
- Smart controls: To schedule heat pump operation around solar generation
- Optional battery storage: 5-10 kWh to store surplus solar for evening use
Daily energy flow
On a typical spring or summer day, the solar panels begin generating electricity from around 7am. By mid-morning, generation often exceeds the home's baseline electrical demand. The smart controls detect this surplus and signal the heat pump to heat your hot water cylinder — storing thermal energy in the hot water rather than exporting electricity cheaply to the grid.
During winter, solar generation drops significantly. A 4 kWp system might produce only 3-5 kWh on a December day compared to 20-25 kWh in June. However, even these modest winter contributions reduce your grid consumption. And because electricity prices are highest in winter, the value per kilowatt-hour saved is actually greater.
Seasonal performance
The seasonal mismatch is the honest challenge of this combination. Your heat pump works hardest in winter when solar generation is lowest. In summer, your panels produce the most electricity but your heating demand is minimal (though hot water demand remains year-round).
This is why the combination works well rather than perfectly. You will not eliminate your electricity bill entirely. But you will reduce it substantially — typically by 40-60% compared to running a heat pump without solar panels.
Combined System Costs and Grants
Let us look at realistic 2026 costs for a combined system on a typical three-bedroom semi-detached home:
Heat pump costs
- Air source heat pump (installed): £10,000 - £14,000
- BUS grant deduction: -£7,500
- Your cost for heat pump: £2,500 - £6,500
See our full heat pump cost breakdown for detailed figures by property type.
Solar PV costs
- 4 kWp solar PV system (installed): £5,000 - £7,000
- With battery storage (5 kWh): £8,000 - £11,000
- VAT: 0% on residential solar PV installations (until March 2027)
For more detail on solar panels specifically, visit our sister site Home Solar Guide, which covers everything from panel selection to installation and maintenance.
Total combined cost
After the BUS grant and with zero-rated VAT on solar, a typical combined system costs between £7,500 and £17,500 depending on system size, property complexity, and whether you add battery storage. That is a significant investment, but it is protecting you against energy costs for the next 20-25 years.
Payback Period: When Does the Investment Pay for Itself?
Payback depends on your current heating system, energy consumption, and how much solar electricity you use directly rather than exporting. Here are realistic scenarios:
Scenario 1: Replacing a gas boiler (no battery)
Annual saving compared to gas boiler: £400-700 per year. Payback on combined system: 11-18 years. This assumes current gas and electricity prices remain broadly stable.
Scenario 2: Replacing a gas boiler (with battery)
Annual saving: £600-900 per year. Payback: 10-16 years. The battery increases self-consumption of solar electricity from roughly 30-40% to 60-70%, boosting savings.
Scenario 3: Replacing oil or LPG heating
Annual saving: £900-1,500 per year. Payback: 6-10 years. Oil and LPG are significantly more expensive than gas, making the economics far more favourable. If you are currently on oil or LPG, a combined heat pump and solar system is one of the smartest investments you can make.
These figures are conservative. If electricity prices rise faster than gas prices — which most analysts expect due to the ongoing electrification of heating and transport — payback periods will shorten. Your running costs with solar are largely insulated from grid price increases.
Should You Add Battery Storage?
A battery stores surplus solar electricity generated during the day for use in the evening and overnight. For a heat pump owner, this means powering the pump with stored solar electricity during peak evening demand.
The case for a battery
- Increases solar self-consumption from roughly 35% to 65-75%
- Reduces grid electricity purchases further
- Provides backup during short power cuts (some models)
- Works well with time-of-use tariffs — charge cheaply overnight, use during peak
The case against
- Adds £3,000-5,000 to the system cost
- Battery lifespan is typically 10-15 years, shorter than panels or heat pump
- Marginal returns diminish if you already have good solar self-consumption
Our view: if you can afford it, a battery makes the combined system significantly more effective. But if budget is tight, installing the heat pump and solar panels without a battery still delivers excellent results. You can always add a battery later.
Smart Controls: Making the Systems Talk to Each Other
The real magic of a combined system happens through intelligent controls. Modern heat pump controllers can integrate with solar PV monitoring to prioritise solar electricity use.
For example, systems from manufacturers like myenergi (the zappi and eddi products) can divert surplus solar electricity to your hot water cylinder or signal your heat pump to run heating cycles when solar generation is high. Some heat pumps have this integration built in.
Smart tariff integration adds another layer. With an agile tariff, your system can use cheap grid electricity overnight, solar during the day, and avoid expensive peak-rate electricity entirely.
Planning and Installation Considerations
Can you install both at the same time?
Yes, and there are advantages to doing so. Some installers offer combined packages, and installing simultaneously can reduce scaffolding and electrical work costs. However, you will typically need separate tradespeople — an MCS-certified heat pump installer and an MCS-certified solar installer. Some companies are certified for both.
Planning permission
Both air source heat pumps and rooftop solar PV usually fall under permitted development and do not require planning permission. Exceptions include listed buildings, conservation areas, and flat roofs. Always check with your local planning authority.
Roof suitability
Solar panels need a roof that is structurally sound, ideally south-facing (though east and west work well too), with minimal shading from trees or neighbouring buildings. Your roof should have at least 15-20 years of life remaining.
Electrical supply
A heat pump and solar PV system combined will need adequate electrical capacity. Most homes have a 100A supply, which is usually sufficient, but older properties with smaller supplies may need an upgrade. Your installer should assess this during the survey.
Real-World Performance: What UK Owners Report
Homeowners running combined systems consistently report electricity bills of £40-80 per month even in winter, dropping to near zero or even credit in summer months. Annual electricity costs of £500-800 are typical for a well-insulated three-bedroom home — compared to £1,200-1,800 for gas heating plus standard electricity.
The most satisfied owners are those who actively manage their energy use — scheduling washing machines and dishwashers during solar peaks, pre-heating the house while the sun is shining, and using smart controls to maximise self-consumption.
For those on ground source heat pumps, the combination is even more effective because ground source systems typically achieve higher COPs, meaning each unit of solar electricity generates even more heat.
Frequently Asked Questions
How many solar panels do I need for a heat pump?
A 4 kWp system (roughly 10 panels) is a good starting point for most homes with a heat pump. This will not cover all your heat pump electricity use, but it will make a substantial dent — particularly in spring, summer, and autumn. Larger homes or those with higher heat demand may benefit from a bigger array if roof space allows.
Can solar panels fully power a heat pump?
In summer, yes — your panels may generate more electricity than your heat pump uses. In winter, no — solar generation drops to a fraction of summer output while heating demand peaks. Over a full year, a 4 kWp system might cover 30-50% of a heat pump's total electricity consumption.
Do I need a battery to combine solar with a heat pump?
No. Your hot water cylinder acts as a thermal battery — heating water during solar peaks stores energy for later use. A battery helps further by storing electrical energy for evening use, but it is an enhancement rather than a requirement.
Can I get grants for both a heat pump and solar panels?
Yes. The BUS grant (£7,500) covers heat pumps specifically, while solar PV benefits from zero-rated VAT. Some local authority schemes and the ECO4 programme may provide additional support for solar installation depending on your circumstances. The grants are separate and you can claim both.
Is it better to install them at the same time or separately?
Either approach works. Installing together can save on electrical work and disruption, but installing separately lets you spread the cost. Many owners install a heat pump first, then add solar within a year or two once they understand their electricity consumption patterns.
How much can I save with a heat pump and solar combined?
A typical three-bedroom semi replacing a gas boiler can expect to save £400-900 per year depending on insulation levels, system size, and whether battery storage is included. Replacing oil or LPG heating delivers even greater savings of £900-1,500 annually. See our calculator for a personalised estimate.