Solar thermal power is heat energy that is obtained with a network of collecting devices, and exposing them, to the rays of the sun. It can be used to heat water or other fluids and to make steam for industrial purposes.
This clean, renewable resource is inexpensive and is an established technology. Simple enough to build and maintain yourself, it is a nice alternative for heating water and lowing your power bills.
In some areas however, solar thermal is not cost-effective, such as in Canada. In cooler climates, freezing can damage the collecting systems components and pipes. These systems are only really effective with sunshine and therefore do not work at night or during long periods of cloudy weather.
Though storage of hot water for residential and commercial use is relatively simple, by using insulated tanks, storage of fluids at a higher temperature for electrical generation is not as simple.
There are several types of solar thermal systems. Solar water heaters, concentrating collectors, and parabolic trough and dish collectors. All of these use the sun's rays to heat a fluid, their methods and equipment differ.
In solar water heaters, water flows through tubes that are attached to a metal absorber plate. The plate is an insulated box with a window to let in sunlight. The heated water can be transported to a tank where it can be used.
Central receivers are used to produce electricity and steam with solar thermal power. Tracking mirrors called heliostats focus sunlight into a single receiver on top a tower. The fluid inside the tower is then heated. The heat can then be used directly or transferred to water to produce steam for electricity.
Parabolic troughs and dish collectors are curved panels that follow the sun's rays and focus the sunlight onto receivers. The fluid inside the pipes absorbs the thermal energy and can be converted to electricity at each unit or transported to a point for conversion to electricity.
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