ABSTRACT
Solar thermal collectors absorb the sun's heat and transmit it to a fluid which is drawn off to transport the heat to where it can do useful work. At the small and medium scale there are three types of collector: flat plate collector; batch system solar collector; and single evacuated tube collector. A medium-scale system would provide hot water for heating a facility or commercial building or apartment block. It will be integrated with another heating system. In such a system, solar heat is used to heat water which can be topped up by other heat sources if and when it is not sufficient. Large-scale collectors are deployed in Sunbelt regions – for example, North Africa, Middle East, south-western USA, southern Europe. They use systems which concentrate the sun's energy onto smaller areas to achieve higher temperatures. Solar tower plants have higher concentration factors and use water-steam, synthetic oil or molten salt as the primary heat transfer fluid.
