Do Heat Pumps and Solar PV complement each other?

Many people today have an understanding of how a heat pump uses energy from the outside air or the ground to produce heating and hot water for your home and/or business.

Electricity is needed to run a heat pump whether it’s an air source heat pump which can produce 3KW or more from 1KW of electricity or a ground source heat pump which can produce 3.5KW or more from 1KW of electricity.

It is also generally understood that solar PV panels are used to generate electricity by absorbing energy from the sun and converting it from DC to AC electrical current.

In the UK the government has put forward the following solutions to meet heat demand and achieve its legally binding climate change targets.

  • A commitment to building and extending heat networks in urban areas.
  • Development of “green gas”, hydrogen or biomethane, that will replace natural gas in the existing grid, if this low-carbon gas can be deployed at scale.
  • Shift away from conventional oil-fired heating to heat pumps in the off-gas areas.

Currently there are around 3.6 million homes in England and Wales that are off the mains gas grid. Of those, around 2 million use electric heating and 1 million use oil heating – of which half are non-condensing. It is interesting to note that most of these dwellings could be targeted for the installation of heat pump-based heating. At the same time there are around 900,000 homes in the UK with solar PV panels installed.

You might naturally conclude from this that solar PV and heat pumps would work very well together with solar PV covering all or most of the heat pump’s electrical requirements. It sounds like a great combination providing free heating forever!

There is however a problem with this combination in that solar PV panels produce a relatively small amount of electricity at the time of year when your heating and hot water demands are at their highest, and furthermore the time of day that the PV produces any excess energy is during the day. This does not follow the typical timings of a heating system.

Solar PV panels will have less impact on lowering costs for running a heat pump during the cold months & during the summer you won’t be using your heat pump much more than to heat hot water though with correct control timings and adequately sized Hot Water cylinders, this can be maximised to give you near free hot water 3-4 months of the year.

There is a solution to this problem however. You can reduce the amount of energy you use in the summer if you have solar PV by installing a solar PV immersion controller to divert any extra electricity generation to your immersion in your thermal store or cylinder to heat your water for free instead of exporting it back to the national grid. You can get solar PV immersion controllers of which there are a few to choose from at £200 and upwards that will give you similar savings and can be installed by any qualified electrician.

There is still a very strong argument and financial benefit for having both heat pumps and solar PV.

Find out more about solar here.

Find out more about heat pumps here.