Solar Heating Panels

If you've been researching solar energy you know that solar heating panels are part of overall solar heating systems.  These systems use different types of collectors to harness the energy of the sun and in some systems, store the energy, and finally use it to distribute heat where and when needed.  Some industrial solar heating panels as well as solar pool heating systems distribute heat immediatley without any storage. All collectors are filled with a heat transfer medium -- either air of liquid.  It is the air or water that is heated and later used to distribute that heat to the desired location.  Types of solar heating panels vary depending on the materials used in their construction and their purpose.

Solar Heating Panels:  Flat Plate Collectors

This is the most commonly used type of collector for residential and small commercial applications.  Almost everyone has seen pictures of them.  They are those big bulky black boxes very often covering the entire southern exposure of the roof of a home or small business location.  The box is made of metal with interior insulation and an absorber plate. It is the absorber plate that does the real work of trapping the sun's energy.  The plates are comprised of different configurations of silicon wafers resulting in photovoltaic cells.  Finally, the box is "glazed" which simlly means covered in glass. Flat plate collectors use either liquid or air and the medium used influences the design and construction of the collector.

Liquid-Filled Flat Plate Collectors

As you would expect these collectors contain tubes to hold and circulate the heating medium, which in many residential applications is simply household water.  The water is piped in, heated, and then piped out to a storage area.  The use of household water makes these systems impractical in areas with extremely low winter temperatures as they are subject to freezing.  More costly systems use a kind of "anti-freeze" solution to get around this shortcoming.

Air-Filled Flat Plate Collectors

As you may know, liquid heats faster, holds heat longer, and conducts heat more efficiently than air.  The implication is obvious:  if you have a choice, go with liquid-filled solar heating panels.  In an air-filled solar heating panel an external fan is used to circulate the air over the absorber plate to heat it.  Passive solar heating panels rely on natural convection to circulate the air.  Because of this they are extremely limited and usually only employed in single room applications, like that pesky home addition that just never warms up enough.  Active solar heating panels are the only real choice for full house or multi-room applications.

There are two other types of flat plate collectors you might run across in your research: Evacuated-Tube Collectors, and Integral Collector Storage Systems (ICS).  Evacuated-Tube Collectors use metal absorber tubes encased in glass outer tubes with enable them to achieve higher temperatures than standard collectors.  This makes them more suitable for large commercial applications but their enhanced designs also makes them more expensive.  ICS systems are used strictly as solar water heaters.  Basically these systems preheat water and then send the water to a conventional water heater where stored until distributed.  So there you have it.  The basics of solar heating panels.  Good luck with your solar heating!