ABSTRACT
Converting the sun’s radiant energy to heat is very common from historical times and has evolved into a well-developed solar conversion technology today. The basic principle of solar thermal collection is that when solar radiation strikes a surface, a part of it is absorbed, thereby increasing the temperature of the surface. The efciency of that surface as a solar collector depends not only on the absorption efciency but also on how the thermal and reradiation losses to the surroundings are minimized and how the energy from the collector is removed for useful purposes. Various solar thermal collectors range from unglazed at plate-type solar collectors operating at approximately 5°C-10°C above the ambient to central receiver concentrating collectors operating at above 1000°C. Table 3.1 lists various types of solar thermal collectors and their typical temperature and concentration ranges.
