How to buy solar panels How solar water heating works
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 explained
The illustration below shows how solar water-heating systems work.
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Heating water from solar panels is a five stage process:
- Solar collector converts light energy from the sun into heat energy.
- Heat energy is then transferred to a heat transfer fluid and this is circulated through the solar collector using a small electrically powered pump.
- Heat transfer fluid flows through the heat exchange coil at the bottom of your hot water cylinder. The heat is then transferred through the coil into the water.
- Heated water rises to the top of the cylinder and is available at taps. Fluid is pumped to the roof again for reheating.
- The boiler provides back-up heat or operates when solar energy is not available.
Replay our solar panels live Q&A
Our team of experts were inundated with questions from homeowners considering their solar options during our live Q&A, covering everything from energy savings and feed-in tariffs to installation, inverters and maintenance.
Missed it? You can rewind and replay all the action at Which.co.uk/solarlive.
- Which? advice: pros and cons of solar water-heating
- Free cash for installing solar thermal using the Renewable Heat Incentive
- Find our how to cut your heating costs
