Can You Run a Heat Pump With Solar?

Air Source or Ground Source?

While you can operate any heat pump with solar panels, it’s useful to know whether this works better for air source or ground source heat pumps. The size of your solar array will depend on how much electricity you can generate, but you can also make use of a system that allows the sun to warm your hot water instead, cutting down on your electricity use for the heat pump.

Heat pump technology is purely electrical, so it requires electricity to run. Operating your heat pump with solar panels seems like a logical move. The ambient temperature is used in the surrounding air or ground to work alongside a compressor to achieve desired warmth. Air source is the cheaper of the two heat pumps, but ground source is more efficient. These two options also branch out into two more choices: whether to opt for solar thermal or photovoltaic.

Operating a Heat Pump With Solar Panels

Solar Thermal

This kind of system connects solar panels to the same circuit as the heating element of your heat pump. It captures the sun’s heat and works in conjunction with the heat pump to reduce the amount of electricity that’s required. It goes a step further than simply using solar thermal technology on its own to warm your hot water, but it requires a hot water cylinder as it can’t produce hot water on demand.

Despite the technology being more efficient than gas boilers and able to provide adequate hot water, pairing a heat pump with solar panels in this way will only provide enough heat for water and not for home heating as well. The only exception to this is thermally efficient homes, which have a much lower space heating demand. If you need both hot water and space heating, it’s better to go with a standard air source or ground source heat pump instead, or to look at using photovoltaics to reduce your electricity demand.

Photovoltaic (PV)

Pairing a heat pump with PV panels supplements the amount of electricity it uses. As this system is designed to replace gas, your electricity bill will go up to compensate. By running your heat pump with solar panels, you can cut down on the power it draws from the grid and reduce your energy bill as a result.

In terms of retrofitting, adding solar panels to your home or simply installing a heat pump will be more cost-effective than replacing the whole system with a solar thermal alternative.

How Many Solar Panels Could Power a Heat Pump?

In order to work out how much power a heat pump with solar panels would require, we need to break down typical levels of energy use.

The average household will use about 3,700kWh of electricity a year, while a heat pump will add an additional 4,000kWh in the same time period. More efficient systems will only add 3,000kWh.

Using a gas boiler, on the other hand, consumes about 12,000kWh for the year, so the efficiency of a heat pump already helps lower the demand it could otherwise be. Essentially, you need to produce around 7,700kWh of energy with your solar panels to cover all your needs for the year.

For the sake of comparison, on average, an EV will use around 4,300kWh a year. A heat pump with solar panels can cover the much lesser demand.

By linking your heat pump with solar panels, you will most likely only be able to power half of your home’s needs while making up for the rest through the national grid. To be solely reliant on solar power, you’d need the right sized system. Heat pumps require around 25% of their heat output in electricity, so a 20kW system will run on 5kW. The less efficient the system, the more electricity required, and the colder the weather, the more electricity needed.

You can see the typical number of panels required for different powered systems in the graph below.

How many solar panels do I need?

Despite being able to run a heat pump with solar panels, 20 panels are needed to power a 20kW system. This will produce around 5kW of power a day, which is enough to cover the operation of the heat pump, but nothing else. And that would only be if the heat pump runs when the solar panels are capturing energy. Without a solar battery to make sure all electricity is used, selling any surplus back to the grid will only recoup some of the cost of running the heat pump.

Is Solar Storage Needed?

Instead of simply supplementing your heat pump with solar panels, it could be more beneficial to install a solar battery as well. This way, your heat pump will still use renewable energy at night when the demand for space heating is higher. While it’s not required in order to pair a heat pump with your solar panels, a solar battery makes it much easier. The only downside to this is the additional cost.

What Would a Heat Pump With Solar Panels Cost?

Air source heat pumps are the cheaper of the two options, averaging around £10,000. Ground source heat pumps, on the other hand, can easily be around the £30,000 mark. The Boiler Upgrade Scheme (BUS) can reduce these amounts by £7,500, but with a solar array averaging £6,000 and a suitable battery system costing £4,000, this adds up. Even without a battery, you can still end up paying over £10,000 for a heat pump with solar panels.

On the cheaper end of the scale, you can pay £12,500 for a heat pump with solar panels and a battery, but that’s with the BUS discount applied. A ground source heat pump could stretch to £34,000 in total for an equivalent system.

What does an air source heat pump cost?

All systems are different, so the cost of a heat pump with solar panels will be more or less depending on which manufacturer you go for, how many solar panels you’ll need and which battery you buy. This only gives you a rough idea of what you could end up paying.