How to buy solar panels How does solar water heating work?
A solar water heating system (also known as a solar thermal system) uses panels fitted to your roof to heat water for use around the home.
Solar water heating works differently to solar photovoltaic (PV) panels, as it provides hot water rather than electricity.
You could have both if you have space on your roof: solar hot water systems shouldn't take too much space on your roof. Solar water heating panels would heat up your hot water while solar PV panels would provide you with free electricity.
If you want to find out more about generating your own electricity using solar panels, see our guide to solar PV panels. Otherwise keep reading to find out how solar water heating works.
How solar water heating works
The illustration below shows how solar water-heating systems work.
Types of solar water heating systems
There are two main types of solar water heating panels – flat plate and evacuated tubes (referring to the way in which water interacts with the panel). Evacuated tubes are more efficient than flat-plate versions, so are often smaller but generate equal amounts of hot water.
There are also drainback systems. These drain water from inside the solar panel when the pump is switched off to prevent water freezing or boiling inside the solar panel.
Solar water heating installation
You will need to hire a professional to install your solar water heating system. There are plenty of solar panel installers out there, so we recommend that you always collect a range of quotes to compare.
You should only use Microgeneration Certification Scheme (MCS)-certified installers and products. Then compare the estimates of costs and savings you are given by salesmen against other sources of advice.
But beware of solar panel sales tactics. When we went undercover to investigate solar water heating companies back in 2010, we found some salesmen using dodgy sales tactics and exaggerating the financial savings that could be made.
We strongly recommend that you do your own research first - read our guide to installing a solar water heating system.
- Read Which? advice on how to install solar water heating panels
- Watch our video to see the dodgy solar thermal sales tactics you need to avoid
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