Solar Thermal

Solar thermal panels use heat from the sun to warm domestic hot water. If needed, a conventional boiler or immersion heater is then used to make the water hotter, or to heat the water entirely, when solar energy is not available. Larger solar panels can also provide energy to heat your home as well – though usually only in the summer months when home heating is not required.

This system is the most popular domestic renewable energy generation system and is becoming more popular as people are realising the money they can save from reduced bills, government incentives and free energy.

How it works

Solar thermal hot water systems use the Sun’s energy to generate hot water for your household needs. An installation of between 4m2 and 6m2 on your roof will provide up to 60% of your hot water needs each year.

Solar thermal panel options

  • Flat plate panels typically comprise a sheet of metal in an insulated box with a transparent lid. This absorbs the Sun’s energy and transfers it to pipe work attached to the collector plate.
  • Evacuated tube panels comprise a heat collector plate within a glass tube containing a vacuum. Evacuated tube panels are more efficient during colder weather, as less heat is lost back to the air outside the panel. However, they are slightly more expensive than flat plate collectors.


A typical solar thermal installation takes a minimum of two days, and includes the following tasks.

  • Taking out the old hot water cylinder
  • Installing a solar twin coil cylinder or thermal store
  • Installing solar panels on the roof
  • Installing pipe work (usually through the loft space), to the hot water cylinder
  • Installing control and pump units
  • Filling up and commissioning the system
  • After installation, we will provide a follow-up call to ensure that the system is working properly.

Things to consider

  • Do you have around 6m2 on your roof to install the panels required?
  • Do you have space inside for a hot water storage tank (around 1m x 1m x 2m high)?
  • What’s your budget? A typical solar thermal system costs between £3,500 and £5,500

What you need

You’ll need space for a new hot water storage tank. These are specially designed with an extra coil to accept the solar contribution. The latest systems commonly include what’s known as a thermal store or heat bank. These provide mains pressure hot water, and also allow excess solar energy to contribute to your room heating requirements in the spring and autumn.

What you can expect to save

A solar thermal system can reduce your water heating bill by between £45 and £85 per year. You can also expect to save up to 600kg of CO2 emissions, depending on what fuel you will be replacing. In general, you can expect an 11% rate of return.