Solar thermal

Solar water heating systems (solar thermal) use heat from the sun to warm water for domestic/non-domestic use. A typical installation consists of the following components -

Solar thermal panels - these are panels placed on the roof of a building to transfer heat from the sun to circulating fluid. There are two common types available -

  • Evacuated tubes - these consist of a series of glass tubes and are generally the highest performing choice.
  • Flat plate collectors - these consist of flat black plates and can be fixed on to roof tiles or integrated into the roof.

Thermal store - these are essentially large insulated water storage devices containing the water that will be supplied to the end user. A thermal store is needed as solar thermal energy collected is diffuse and accumulated throughout the day for use.

Supplementary heat source - solar thermal systems often have a supplementary heat source to ensure an adequate supply of water during low output days.

Pump - this is used to pump the circulating fluid around the system, transferring heat from the rooftop to the thermal store. These are often powered by a small additional solar PV unit.

What are the benefits?

There are a number of advantages to installing a solar thermal heating system in a domestic or non-domestic scenario which include -

  • Solar thermal is a mature, well developed technology with few operational issues, where proper maintenance is undertaken.
  • Solar thermal can help reduce costs and carbon emissions associated with heating hot water.
  • Community solar thermal systems work particularly well where there is a large heat requirement, especially in summer.
  • Income can be generated from the domestic or non-domestic renewable heat incentive.

Key points to consider for community solar thermal

Site selection - existing community solar thermal installations involve a single building with a suitable heat load. These could include - sports centres, swimming pools, care homes, hospitals, farm buildings or camp sites.

Installer - An MCS approved installer is essential to claim renewable heat incentive payments. It is advisable to get several quotes from installers to ensure value for money. Solar thermal systems can be complicated and must be designed correctly to maximise the investment.

Incentives - income for the solar thermal system will primarily come from the Renewable Heat Incentive (RHI) and depends on the size of the solar array and the profile of the heat load to be met. The installer will be able to give indicative figures for the annual income generation. More information can be found in the RHI module.

Savings - in addition to income from RHI a solar thermal system will displace fossil fuel generation and therefore result in cost savings to the community group or organisation utilising the energy.

Access the full Solar thermal module.


Further information

The Ofgem RHI website has details of tariffs, regulations and how to apply.

The Energy Saving Trust has guidance on planning permission and how to make the most of solar thermal systems.


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