In this article

What are air source heat pumps, and how do they work?

How much electricity does an air source heat pump need to run?

Are solar panels compatible with air source heat pumps?

How many solar panels will I need?

What happens if the solar panels don't produce enough electricity?

What are the advantages of using solar panels to power an air source heat pump?

Air source heat pumps - a new way to heat your home


Homeowners are increasingly aware of the rising costs of heating their homes, and many, too, are conscious of the effects of fossil fuels on the environment. Hence why we’re seeing more and more homeowners turning to renewable solutions.

According to Solar Energy UK (previously named The Solar Trade Association), around 900,000 British homes have solar PV panels installed. Solar panels generate free, renewable electricity from energy produced by the sun’s rays. Using this energy in a domestic setting can significantly reduce demand from the grid.

Another renewable technology that is rising in popularity is the air source heat pump. Air source heat pumps run off electricity to provide heating and hot water in a cost-effective, sustainable and environmentally-friendly manner. So why not consider combining the two technologies and use solar panels to power your air source heat pump?

Here we’ll examine the compatibility and advantages of combining solar panels with an air source heat pump.


What are air source heat pumps, and how do they work?

Air source heat pumps can replace or (in the case of hybrid heating) complement your home’s boiler. They work by drawing air into the unit installed on the exterior of the home. The air turns a refrigerant inside the unit into vapour. It then compresses the vapour to create heat. Finally, the heat is transferred into your home’s heating system to provide you with heating and hot water. 

Air source heat pumps can do all the things a boiler does. However, instead of relying on gas or oil as primary fuel sources, they run off electricity.


How much electricity does an air source heat pump need to run

Air source heat pumps are known as being one of the most energy-efficient ways to heat a home. Depending on the Coefficient of Performance (CoP) of air source heat pumps, they can achieve efficiency rates of 200-350%, as the amount of heat they generate is significantly greater than the electricity input per unit of energy. Compared to a boiler, heat pumps are up to 350% (3 to 4 times) more efficient, as they consume far less energy relative to the heat they output for use in the home.

The amount of energy an air source heat pump needs to run depends on several factors, including the local climate and seasonality, the ductwork and insulation condition and the property's condition and size.

When calculating the amount of electricity you’ll need to run an air source heat pump, you need to consider its CoP. The higher it is, the better, because it means you’ll use less electricity to generate the amount of heat you demand.

Let’s look at an example…

For every 1 kWh of electricity, an air source heat pump can produce 3kWh of heat. The average annual demand for most UK homes is around 12,000 kWh.

12,000 kWh (heat demand) / 3kWh (heat produced per unit of electricity) = 4,000 kWh of electricity.

If your electricity is priced at £0.15 a unit¹, it will cost you £600 to run your air source heat pump.

However, it's free if you can run your air source heat pump with electricity generated by your solar panels. But is it really viable?


Are solar panels compatible with air source heat pumps?

Solar panels can technically power virtually any appliance in your home, from your washing machine to your TV. And even better, they can also power your air source heat pump!

Yes, it's possible to combine solar photovoltaic (PV) panels with an air source heat pump to generate both heating and hot water to meet your needs while being kinder to the environment.

But can you power your air source heat pump with solar panels exclusively? Well, that will depend on the size of your solar panels.

Unfortunately, it’s not as easy as sticking a few solar panels on your roof. The amount of electricity a solar panel generates will largely depend on the size of the solar panel, the efficiency of the solar cells and the amount of peak sunlight in your location.

Solar photovoltaic panels work by absorbing sunlight and converting it into electricity. So the bigger the surface area of the solar panels, the more sunlight they'll absorb and the more electricity they'll generate. It also pays to have as many solar panels as you can, especially if you're hoping to power an air source heat pump.

Solar panel systems are sized in kW, with the measurement referring to the amount of power produced by the panels per peak hour of sunlight. The average solar panel system is around 3-4 kW, which reflects the maximum output produced on a very sunny day. This figure might be less if it’s cloudy or in the early morning or evenings when the sun is not at its peak. A 4kW system will generate around 3,400 kWh of electricity per year.


How many solar panels will I need?

The average solar panels produce around 250 watts, which means you would need to install 4 panels to create a 1 kW system. For a 2kW system, you’d need 8 panels, and for a 3kW you would need 12 panels. You get the jist of it.

An average household (family of 4) would likely require a 3-4kW solar panel system to produce enough electricity to power the home, which equates to 12-16 panels.

But returning to our earlier calculation, an air source heat pump will need 4,000 kWh of electricity to produce 12,000 kWh (heat demand), so you will likely need a larger system of 16+ panels to power your air source heat pump exclusively.

This means that while solar panels should be able to produce most of the electricity you require to power your air source heat pump, they’re unlikely to generate enough electricity to power other home appliances without using electricity from the grid.

The best way to find out how many solar panels you’ll require for your home is to have an assessment carried out by a qualified engineer. They will advise you on how many solar panels you’ll need to power your home and your air source heat pump.


What happens if the solar panels don’t produce enough electricity?

If your solar panels don't produce enough electricity to power your home or air source heat pump, you will be able to use energy from the grid to meet your demands. Remember that you will pay for any energy you use from the grid. Hence, it's essential to get a professional evaluation of the number of solar panels to power your air source heat pump.


What are the advantages of using solar panels to power an air source heat pump?

Cost savings

Depending on your current heating source, an air source heat pump could save you up to £1,300 per year on your heating bills. Air source heat pumps tend to be more cost-effective to run than non-renewable alternatives like oil and LPG boilers, and these savings will increase by powering your heat pump with solar panels.

Air source heat pumps are powered by electricity, so you can minimise your heating costs by running them off free solar energy generated from your panels.

Protection against rising energy costs

By powering your air source heat pump with solar panel energy, you protect yourself against rising energy costs. Once you’ve paid off the installation cost of your solar panels, the energy you generate is free, so you won’t have to worry about an increase in gas, oil or electricity at any point.

Reduced reliance on the grid and carbon footprint

By switching to air source heat pumps powered by solar panels, homeowners can reduce their reliance on the grid supply of electricity and gas. Seeing as the grid is still primarily made of non-renewable energy (and we all know how bad fossil fuels are for the environment), this is a great way to cut your carbon emissions and reduce your carbon footprint.


Air source heat pumps - a new way to heat your home

Whether you’re looking to replace an old boiler or reduce your carbon footprint, air source heat pumps can provide an efficient and cost-effective way to heat your home. Plus, if you already have solar panels installed or are looking to install them in the near future, it’s well worth making the switch and benefiting from free electricity to run your air source heat pump.

With Igloo’s Clean Heat Switch, air source heat pump installation prices start from £4,000, and the government’s Renewable Heat Incentive can be used to help cover part or all of the cost. For more information, get an instant quote on your screen by clicking below.





1 Igloo UK average electricity unit price of 15.66p (as of July 2021)