What Is Solar Thermal?

What is Solar Thermal?

Solar water heating (also known as solar thermal), is the process of capturing energy from the sun via the use of solar panels, to heat water for use in the home. Solar thermal offers much lower heating costs than traditional gas or electric-powered heating systems and produces fewer carbon emissions. This makes it a popular choice for homeowners looking to reduce their carbon footprint.

How does Solar Thermal work?

This type of system uses solar thermal panels, (also known as solar collectors) to collect energy from the sun. Solar thermal panels are a different type of technology than conventional solar PV panels, which use photovoltaic cells to capture the sun rays before turning it into electricity.

Solar collectors are made up of cells containing a fluid which absorbs heat directly from the sun. The heated fluid is then transferred to a coil fitted inside the hot water cylinder. The coil helps transfer the heat to the water stored in the cylinder. Once the heat transfer is complete the liquid is pumped back into the collectors, where the cycle starts again.

Types of Solar Collectors:

Evacuated tubes – This type of panel is made up of many small glass tubes. Each tube consists of an inner and outer tube. The inner tube is mounted in a vacuum to prevent heat loss and coated in a light-absorbing material to maximise the absorption of light. The fluid is heated in the tube before being transferred to the hot water cylinder.

Flat plate collectors – This type of panel consists of an absorber plate mounted inside an insulated container. The top of the container is made of glass to let in the sun’s light, while the insulation prevents heat from being lost. Tiny glass tubes filled with fluid pass through the absorber plate which transfers heat from the plate to the fluid. The heated fluid is then transferred to the hot water cylinder.

In practice, both types of panel offer similar levels of performance. So the choice usually comes down to aesthetics.

Are solar thermal panels suitable for your home?

While solar thermal is a tried and tested way of heating water, the level of performance achieved is dependent on several external factors. To achieve the greatest efficiency the collectors should be mounted in a south-easterly or south-westerly direction. This will maximise the amount of sunlight they are exposed to each day.

Ideally, the solar thermal panels should be mounted on a pitched roof of between 20º and 50º from horizontal. But they can also be mounted in the garden or flat roofs using angled brackets. Wherever they are installed, the level of shade the panels are subjected to at different times of the day should also be considered.

Homeowners should also think about the number of people the solar thermal system will have to provide hot water for. A typical installation should allow for between 1-2㎡ of solar thermal panels for each person in the household. If you do not have enough available space this type of system may not be practical.

How Much Do Solar Thermal Systems Cost?

A solar thermal system will typically be priced between £4,000 and £6,000; this includes installation with all parts (solar collectors, control panel, pipes, hot-water tank) and not forgetting an increased VAT rate of 20% (introduced by the government on October 1st 2019, this was previously 5%).

Other factors including the quality of the panels you choose, the work required, parts needed, where you live, and who you choose to carry out the install will all have an impact on the final price.

Once you’ve covered the initial outlay of your solar thermal system, then on-going costs will be kept to a minimum, as they’re low-key when it comes to maintenance and cost effective to run – most solar thermal systems also come with a 10-year warranty too, for complete peace of mind.

Advantages of Solar Thermal

• Solar thermal makes use of free energy from the sun.
• Once the installation is complete there are no other costs associated with this type of heating.
• The technology can help to reduce energy bills because you will use less gas or electricity.
• Solar water heaters release fewer carbon emissions than traditional gas or electric water heaters.
• Homes which install solar thermal may qualify for government incentives such as the Renewable Heat Incentive to help offset installation costs.
• Maintenance costs for solar thermal heating systems are generally very low.

Disadvantages of Solar Thermal

• Because the technology relies on heat from the sun, it can not be used as a standalone system. A backup immersion-heater or conventionally powered boiler will also be needed to provide enough hot water during the winter months.
• The cost of installing solar thermal panels is more than the cost of a conventional heating system. Although the cost is coming down, a typical system will cost several thousand pounds to install. However, incentives are available to help offset the cost.

Is Solar Thermal Worth It?

There is no doubt that solar thermal is a tried and tested method of heating homes in an environmentally friendly way. The systems are quite simple and don’t require much in the way of maintenance. While the cost of installation may be prohibitive for some, this will be offset by lower running costs

Incentives may be available to help cover installation costs, although this can change at any time. To benefit from any incentives you will need to ensure your solar thermal system is installed by an MCS certified installer. This will also give you peace of mind that your system has been installed correctly and is working efficiently.