Solar Thermal

By Katie Anderson on July 27th, 2011


Solar thermal energy is a clean and efficient means of harnessing the free renewable energy from the sun to warm domestic hot water used in the home.

Solar thermal – also referred to as solar water heating – generates renewable heated water using solar panels or “collectors” which have been installed on the roof of a property to gather energy from the sun.

A solar thermal system consists of solar panels (or collectors), a pump station, a twin coil cylinder, a solar cylinder and a boiler.

A conventional boiler or an immersion heater will make the water hotter, and will be able to provide hot water when solar energy is unavailable, which is most likely to be during the winter months. Solar thermal systems work well all year round, and can cut hot water costs and reducing carbon dioxide emissions.

There are two main types of solar collectors: flat plate collectors and evacuated tube collectors.

The Government has introduced the Renewable Heat Incentive (RHI) as a way of providing financial assistance to people interested in switching to an alternative source of heating, such as solar water heating.

Is solar thermal suitable for my home?

As a general rule, there are a few key points to consider to determine whether solar water heating is suitable for your property:

  • You’ll ideally need around 4 square metres of unobstructed roof space facing anywhere from southeast to southwest.
  • You will need to check whether you have the space for a larger, or even an extra, hot water cylinder.
  • Your current boiler needs to be compatible with solar water heating. Most conventional boiler and hot water cylinder systems are compatible with solar water heating. But if you have a combination boiler (combi) and you don’t currently have a hot water tank then a solar hot water system may not be compatible.
  • Check whether you need planning permission. In England most solar water heating systems don’t need planning permission, but it is always best to consult your local planning office first, particularly if you live in a listed building or in a building which is in a conservation area. In Wales, Scotland or Northern Ireland you will need to consult your local authority.
  • The size and type of panels used, the existing hot water provision and the hot water cylinder you choose will all affect the overall cost of a solar hot water system.

10 Top Facts

1. Architect Frank Bridgers is believed to have designed the world’s first commercial office building that used the sun for heat and hot water in the mid-1950s.
2. Unlike solar PV, solar thermal power plants generate electricity indirectly.
3. Solar thermal systems comprise of three main parts: solar panels, a heat transfer system, and a hot water cylinder.
4. Maintenance costs are very low and systems require little maintenance. Most solar water heating systems come with a 5-10 year warranty.
5. A correctly sized and installed solar thermal system can provide around a third of your annual hot water needs.
6. After the initial installation cost and maintenance there are no other fees or bills.
7. Solar thermal has no emissions so it is great for the environment.
8. Solar thermal collectors are usually roof mounted.
9. Solar thermal water heating works in a similar way to leaving a hosepipe in the sun.
10. It is not advisable to install solar panels on a north facing roof.

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