Can you run a heat pump on solar?

You can combine a heat pump heating system with solar panels to ensure that your heating and hot water needs are met while also being environmentally friendly. It’s entirely possible that solar panels would be able to produce all the electricity you need to run your heat pump depending on the size of the solar array. That is, on balance you would generate more electricity than you would use over the course of a year, although this would not be applicable to night time usage.

There are two different types of solar energy – solar thermal and photovoltaic.

As solar thermal uses heat from the sun to warm your hot water, this can help reduce the electrical energy required by the heat pump to meet your needs.

In contrast, solar photovoltaic (PV) systems convert energy from the sun into electricity. This electricity can be used to help power your heat pump, reducing your need for electricity from the grid that is mostly created by burning fossil fuels.

Generally, solar panel systems are sized in kilowatts (kW). This measurement refers to the amount of power that is produced by the panels per hour when the sun is at its strongest. The average system is around three to four kW and this reflects the maximum output that can be produced on a very clear sunny day. This figure could be less if it’s cloudy or during early mornings and evenings when the sun is at its weakest. A four kW system will generate around 3,400 kWh of electricity per year and will take up around 26 m2 of roof space.

But is this enough?

The average UK home uses around 3,700 kWh of electricity per year, meaning that a four kW solar panel system should almost provide all the electricity you need. A small percentage would need to be used from the grid.

However, it’s worth noting that the average property uses a boiler, and not a heat pump, to provide heating and hot water. In these homes, gas consumption will be higher and electricity usage lower. But heat pumps use more electricity - even one that is very efficient with a CoP of four uses around 3,000 kWh per year. This means that while solar panels should be able to produce most, if not all, of the electricity that you need to heat your home and water, they are unlikely to be able to power both your heat pump and other appliances without assistance from the grid. Based on the figures above, the solar panels should be able to provide around 50 per cent of the electricity the household would need in total, with the remaining 50 per cent coming from the grid (or from other renewable methods, such as a small wind turbine if you have one installed).