Solar collector is a mechanical device which captures the radiant solar energy and converts it to useful thermal energy . The use of solar energy for heat production dates from antiquity.
There are two main types of collectors: non-concentration and concentrating collectors. In non-concentration collectors, the collector area and absorber area are the same. These collectors intercept solar radiation and absorb it without concentrating it.
Solar thermal collectors are systems that allow for the use of solar energy in thermal applications. These collectors utilize a heat transfer fluid to transport absorbed solar radiation to applications where they are needed.
Fig. 4. Classification of flat-plate solar collectors These collectors are of two basic types based on heat transfer fluid : liquid type and air type (Table 2).
Special collectors have been developed for heating seasonal swimming pools: they are unglazed and made of a special copolymer plastic. These collectors cannot withstand freezing conditions. Approximate maximum operating temperature of such type of solar collector is 10 – 20 o C above ambience. 3. Flat-plate collector
These collectors are so designed to work on direct sun radiation. These collectors are mainly classified into two categories, namely: Line Focusing Collectors: The solar radiation coming from a particular direction is collected over the area of the reflecting surface and is concentrated at the Focus, F of the Parabola.