Solar Thermal : How it works-video

Solar thermal heating systems harvest solar energy through a collector which absorbs energy from the sun, this energy is transferred into heat in a glycole solution that flows through heat in the collector and the heat is then transferred to the water which is stored in a conventiona hot water system.

  • Solar thermal panels are mounted on your roof or on the ground using brackets and frames (flat plate or evacuated tubes)
  • Heat transfer fluid – this can be water, ethylene glycol (commonly known as anti-freeze), or a mixture of the two
  • A coil heat exchanger within a water cylinder – this ‘twin coil’ cylinder will replace your existing cylinder and include a backup coil from your existing boiler to provide extra water heating when required
  • A pump which circulates the heat transfer fluid between panels and cylinder (the pump is usually powered by mains electricity, but can also be powered by a small photovoltaic cell)
  • Insulated pipes between the panels and the water cylinder – called flow and return piping
  • A system control panel which controls the heat transfer fluid pump and provides information on the system’s performance, as well as any faults should one develop
  • A heat flow generation meter, which measures the output of the system – this is necessary in order to claim Renewable Heat Incentive payments
  • Master of Information Technology


Solar water heating systems, or ‘solar thermal’ systems, use free heat from the sun to warm domestic hot water. A conventional boiler or immersion heater can be used to make the water hotter, or to provide hot water when solar energy is unavailable.

Hot Water Throughout the Year

The system works all year round, though you’ll need to heat the water further with a boiler or immersion heater during the winter months.

Reduced Energy Bills

Sunlight is free, so once you’ve paid for the initial installation your hot water costs will be reduced

Lower Carbon Footprint

Solar hot water is a green, renewable heating system and can reduce your carbon dioxide emissions

Claim Renewable Heat Incentive

You will be paid for generating your own heat energy regardless of whether you use it all. There’s a user-friendly calculator available which tells you how much you can earn through this scheme. It can be hundreds of pounds a year!

Is solar water heating right for your home?

Things to consider:


Sunny Spot

Do you have a sunny place to put solar panels? You’ll need around five square metres of roof space which faces East to West through South and receives direct sunlight for the main part of the day. The panels don’t have to be mounted on a roof however. They can be fixed to a frame on a flat roof or hang from a wall.


Extra Cylinder

If a dedicated solar cylinder is not already installed then you will usually need to replace the existing cylinder, or add a dedicated cylinder with a solar heating coil.





Compatible Boiler?

Most conventional boiler and hot water cylinder systems are compatible with solar water heating. If your boiler is a combination boiler (combi) and you don’t currently have a hot water tank, a solar hot water system may not be compatible.



Energy Certificate

It is a good idea to have an Energy Performance survey carried out to check if you are maximising the energy use. If you don’t, you should make the necessary changes before installing the SWH and applying for the FiT, which will guarantee a better FiT rate as well.