So how does a solar thermal system work?
An electronic control unit monitors the temperature in the solar panels (collectors) and also the water in the cylinder. When the temperature in the collectors is higher than the temperature of the water in the cylinder, the controller operates the pump and a special fluid is circulated through the solar panels where it is heated by the suns rays. As the heated fluid passes thought the heat exchanger in the cylinder, the water in the cylinder is heated and the fluid is returned to the solar panels to be reheated. All of the water in the cylinder is gradually heated in this way.
The special fluid contained in a solar thermal system is a glycol/water mix that can withstand the extreme temperatures often seen in a solar thermal system and does not freeze at temperatures down to -25°C. |
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Solar radiation in the UK
Many people believe that solar panels only work in the summer; however this type of free energy is available throughout the year. From May to September a well designed, properly installed solar system can produce 100% of the energy required for heating your domestic hot water. Solar panels operate not just with direct sunlight, but also diffused sunlight, so they even work on cloudy days.
This diagram shows the total average solar radiation falling on 1m2 surface, inclined at 30° to the horizontal, measured in kilowatt-hours (KWh). The average property requires approximately 3,000 kWh per year for domestic water heating
