Solar Thermal Hot Water Systems FAQs

A Solar PV system uses panels (usually called ‘modules’) that generate electricity in the presence of sunlight. The amount of electricity produced depends on the intensity of the sunlight. Solar thermal, on the other hand, uses sunlight to heat a fluid. In the case of Grant solar collectors, it heats a glycol/water solution within the collector. This heated fluid is then circulated from the collector to a cylinder where the heat is transferred to produce hot water.

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The installation of the Grant Solar Thermal system must be carried out by a competent trained person in accordance with the relevant requirements for health and safety, local building regulations, building standards in Scotland and regulations and bylaws of the local water company.

In most instances, the installation of a solar thermal system does not require planning permission. 

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Many people believe that solar collectors only work in the summer, however this type of free energy is available throughout the year. From May to September, solar thermal could produce 100% of the energy required for heating your domestic water. Grant collectors operate not just with direct sunlight, but also diffused sunlight, so they even work on cloudy days.

For installations in the UK, solar thermal collectors will perform best when facing due south at an angle of between 30 - 45°. However, collectors facing south west or south east will perform almost as well. Failing that a collectors facing due west will perform better than those facing due east. North facing solar thermal collectors are not usually used.

Grant solar thermal collectors can be fitted on many different types of roof, both flat and pitched. Collectors can be mounted either just above the roof covering or set into the roof, as required.

No. Grant Solar Thermal systems require only basic maintenance in order to ensure that they continue to give trouble free operation.

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Whilst solar thermal can be used to contribute to the heating of a house using a thermal store, it is more usually used to heat your domestic hot water cylinder and provide hot water to your taps. 

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A Grant solar thermal system requires a cylinder with a solar coil. In many cases this will be a ‘twin coil’ cylinder with both a boiler coil and a solar coil. This may well mean that your existing hot water cylinder will have to be replaced by a suitably sized twin coil cylinder to maximise the performance of your solar thermal system.

Yes. Solar Thermal collectors can be used to provide heat for a swimming pool.

No. The solar fluid used in a Grant solar thermal system is a 40% propylene glycol solution. This provides frost protection for the collectors and external pipework down to -25°C.

Between 1st April 2022 through to 31st March 2027, the rate of VAT on the installation of certain energy saving materials, such as a solar thermal system, is 0%. If you have a solar thermal system installed at your home during this period and you live in Great Britain, you should not have to pay VAT.

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