Solar Thermal Hot Water Systems FAQs

Here are a selection of commonly asked questions about solar thermal systems including general questions, installation and pre-installation queries, and costs and savings questions.

What are solar thermal collectors and how do they work?

Solar thermal collectors cleverly extract the free energy from the sun and transfer this energy to heat a home's hot water system. The collector features serpentine pipework beneath the top layer of glass, through which a special solution flows - as this fluid passes through the collector, the fluid is heated up and then is transferred away from the collector to then heat up water stored within a cylinder which will fulfil hot water demands at the tap. Solar thermal collectors are efficient and an eco-friendly solution for heating domestic hot water, utilising energy from the sun and reducing a home's reliance on fossil fuels.

Read More
Can solar thermal be used to heat my house?

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. 

Read More
Will the solar panels still work on a cloudy day?

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.

What is the difference between solar thermal and Solar PV?

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.

Read More
Does it matter what direction the solar thermal collectors are facing?

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.

Can solar thermal collectors be mounted on any type of roof?
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.
Can solar thermal be used to heat a swimming pool?
Yes. Solar Thermal collectors can be used to provide heat for a swimming pool.
Could the collectors of a Grant Solar Thermal system freeze up in cold weather?
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.
What are the advantages of using solar thermal collectors?

There are multiple advantages and benefits of installing solar thermal collectors at your home. Firstly, a solar thermal system can fulfil a significant proportion of your annual hot water demand, reducing the demand on the heat source in your central heating system, whether that be a traditional boiler or heat pump. Secondly, the sun's energy is free so utilising this heat energy to heat the hot water in your taps can help reduce your energy bills. Solar Thermal systems, such as those supplied by Grant UK, are also incredibly straightforward to live with requiring minimal maintenance. 

Are solar thermal collectors suitable for residential use?

Yes, solar thermal collectors are suitable for installation at domestic properties, residential dwellings and residentials flats.

What factors should be considered when selecting solar thermal collectors?

There are several factors that need to be taken into consideration when selecting the right solar thermal system for your home. These include: size of property and its DHW demand, the orientation of the roof, the shape of the roof, and any objects obscuring the roof. 

Who can install Grant Solar Thermal?
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.
Is planning permission required for solar thermal panels?

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

Read More
Are there any certifications or standards I should look for when choosing solar thermal panels?

Solar water heating products can be certified under one or more standards, such as the Microgeneration Certification Scheme (MCS) or Solar Keymark. These are certifications issued to products that meet recognised standards relating to performance and quality build. Grant’s Solar Thermal Systems are both MCS certified and Solar Keymark approved.

Do solar thermal systems require a lot of maintenance?

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

Read More
Can solar thermal collectors be integrated into existing heating systems?

Yes, solar thermal collectors can be installed as part of a new heating system or they can be added to an existing heating system. Read more about Grant Solar Thermal Systems here.

Can solar thermal collectors be combined with other renewable energy technologies?

Yes, a solar thermal system can be installed alongside other renewable technologies such as air source heat pumps. A popular combination of Grant renewable products includes the installation of an Aerona³ heat pump, solar thermal system, and QR twin coil hot water cylinder.

Read More
Can a solar thermal system be used with my existing hot water cylinder?

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.

Do I have to pay VAT when installing solar thermal?

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.

Read More
What is the cost of installing solar thermal collectors?

The cost of installing a solar thermal system will vary depending on the size of the system, the number of collectors required, and the complexity of the installation. The Energy Savings Trust estimates that the cost of installing a typical solar thermal water heating system is between £3,000 - £5,000. It is recommended that you approach more than one installer to obtain quotations specific for your home and its requirements. Find an installer here.

Read More
How do solar thermal collectors contribute to reducing carbon emissions?

Solar thermal systems can help reduce carbon emissions because they capture the renewable energy from the sun and transfer this into heating the hot water within our homes, reducing the demand on fossil fuel appliances, such as oil or gas boilers, which have traditionally fulfilled both space heating and domestic hot water production in homes. 

What questions should I ask solar thermal panel installers?

When talking with solar thermal installers and obtaining quotations from them, consider asking the following questions:

  • Are you a member of a trade organisation such as the Solar Trade Association?
  • What options do I have in terms of panel size, type, and hot water storage?
  • What type of collector do you recommend? (e.g., flat plate panels or in-roof or on-roof mounting arrangements)
  • Do you have knowledge of applicable regulations and safety guidelines?
  • Will the system be eligible for any Government financial support?
  • What is included in the quoted price, such as removal and disposal of existing equipment and safe access to the roof?
Read More
What can I expect to achieve by installing solar thermal panels?

Solar thermal panels can help you reduce your carbon footprint as well as your energy bills by utilising the sun's free energy to heat your home’s water. Each property’s carbon and cost savings will vary but the Energy Savings Trust has shared a useful infographic which details an example summary of savings made throughout the year.

Return to top

Looking for further product information?

Get the latest Grant brochures, data sheets and manuals from our comprehensive download centre.

Take me there


Use our online enquiry form to send us any comments or questions

Contact Us
Return to top