Solar Thermal – Frequently asked questions

How does a solar thermal system work?
Solar thermal collectors (flat plate panels or evacuated tubes) are installed upon the roof of your property. Inside the collector is a solar fluid which is heated by the sun. Then it is pumped through a pipe coiled inside a hot water tank, which heats up the water. Hot water is then available to use and the solar fluid is pumped back to the collector where it is heated up by the sun again.

Whats the difference flat plates and evacuated tubes?
Evacuated tubes tend to provide a higher energy yield than flat plate systems in the spring/autumn time, however in the summer a correctly sized flat plate system will provide up to 100% of the hot water demand. Tubes generally also require slightly less roof space to yield the same amount of energy.
Flat plate systems have the benefit of being able to be fully integrated into the roof line, which has a better appearance and also saves money on other roofing materials. Flat plate systems also benefit from lower initial costs and lower maintenance requirements.

What is the difference between solar thermal and solar photovoltaics (PV)?
Solar thermal technology is using the power of the sun to heat water. Solar photovoltaics (PV) technology is using the power of the sun to produce electricity. Both systems can be incorporated upon a single roof space.

Do solar thermal systems produce hot water in the winter? What about when it is cloudy and/or overcast?
Solar thermal systems only require daylight to operate; this means they will still heat water on cloudy days. Whilst the majority of solar energy is generated in the summer months a solar thermal system will still contribute towards hot water requirements in spring, autumn and winter, providing for up to 60% of the annual hot water requirements of a property.

Does my roof need to face south?
A south facing roof is the ideal for a solar thermal system for optimum performance however anything between south east and south west also performs well and could generate heat for up to 60% of your annual hot water requirements.

How much space do I need upon my roof for a solar thermal system?
A two panel system, which will produce enough hot water for 4 people, will take up approximately 4m² of roof space.

How long will an installation take?
Typically a solar thermal installation will take 2-3 days to install, however all WDS Green Energy systems are bespoke designs and, especially if installing in conjunction with a heat pump system, your installation could take a little longer.

Do I need planning permission to install a solar thermal system?
Generally no, solar thermal installations fall under permitted development however if your property is a listed building or in a conservation area you may need planning permission.

Can I heat my house and hot water with solar thermal?
Solar thermal systems can provide for up to 60% of the annual hot water requirements for a property. As we need heat in the winter when solar radiation is at a minimum (days are shorter) solar thermal systems are not suitable to provide for a properties heating requirements, however they are ideal integrated as a pre-heat system for an air source heat pump or ground source heat pump system which will provide for all the heating and hot water requirements of the property.

Are there any grants and incentives available for solar thermal systems?
Solar thermal systems are a qualifying technology for the Renewable heat incentive (RHI). This means if you have approved panels installed by an MCS approved installer, such as WDS Green Energy, then you could generate an inflation linked income from your system for seven years.

What maintenance will my solar thermal system require?
Solar thermal systems require little to no maintenance although WDS Green Energy recommends a top up of the antifreeze in the solar fluid and pressure checking of the system every few years to ensure your system continues to operate at peak efficiency.

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