Friday, January 9, 2015

What is solar water heating?

Solar water heating is nothing but the conversion of sun light into renewable energy for heating the water by using a solar thermal collector.  There are a number of technologies available worldwide for solar water heating systems.  

For heating water using solar energy, a collector fastened to a roof or a wall facing the sun heating the working fluid which is either pumped ( in active systems ) or driven by natural convection ( passive systems ) through it.  The collector could be made of simple glass-topped insulated box with a flat solar absorber made of sheet metal attached to copper heat exchanger pipes and dark colored.  or a set of metal tubes surrounded by an evacuated glass cylinder.  The heat transfer fluid for the absorber may be the hot water from the tank but more commonly is a separate loop of fluid containing anti-freeze and corrosion inhibitor which delivers heat to the tank through a heat exchanger ( commonly a coil of copper heat exchanger tubing within the tank ).  Copper is very important component in solar thermal heating and cooling systems because of its high heat conductivity, resistance to atmospheric and water corrosion.  

Residential solar heating installations fall into two categories - Passive and Active systems. Both of these systems typically include an auxiliary energy source ( electric heating element or connection to a gas or fuel central heating system ) which is activated when the water in the  tank falls below a minimum temperature setting such as 55  °C.  Hence hot water is always available.  

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