Solar Thermal Heating
Solar energy is used to heat water via solar collectors located, usually, on your roof. The hot water generated is then stored in a hot water cylinder. Please click on the image on the right to see a schematic plan of a solar hot water system.
There are many benefits of solar hot water including reducing fuel bills and cutting your fossil fuel usage. Another benefit is that you are decreasing the load on your boiler by approximately 70% and therefore prolonging your boilers life.
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How does it work?
Each glass tube on your panel is a vacuum (the air has been removed). This means that the panels performance is not altered by the atmospheric temperature, but only by the intensity of the sun, i.e on a bitterly cold, but clear sunny day, hot water will still be generated.
Heat energy is transferred to heat transfer fluid (antifreeze) and travels down to your hot water cylinder to heat up the water. If there is not sufficient heat provided by the sun, your backup boiler will automatically switch on to boost the temperature so you always have hot water available.
There are two types of cylinder, which are explained below:
Twin coil cylinder:
Hot heat transfer fluid runs from the panels to a coil in the bottom of your twin coil tank. This heats up the water within your tank, which flows out when the tap is turned on. The tank is then refilled with cold water from the your existing roof tank.
Advantages of the Twin Coil Cylinder:
- The cheapest form of solar hot water.
- Good for heating your domestic hot water, suits most domestic properties
Disadvantages of the Twin Coil Cylinder:
- Longer tank recovery times
- Still requires a water storage tank in the roof
Thermal store or Torrent:
The heat transfer fluid runs from the panels to a coil in the cylinder. This heats up the body of water in your tank. This water gets to a very high temperature (85 degrees). When you turn on the hot tap, incoming cold mains water flows through a large coil in the thermal store, heating up this water rapidly. Unlike the twin coil tank, the hot water in the torrent never leaves, but instead acts like a thermal battery, heating up the water as it flows through it.
Advantages of Thermal Store:
- More heat energy can be stored for longer periods
- Mains pressure hot water
- Total tank recovery time in only 10 minutes
- Can add other renewable sources to the thermal store, i.e wood burner, Air source heat pump.
Disadvantages of Thermal Store:
- Higher installation cost
- Does not suit all domestic properties
