Flat Plate Collector

The solar energy devices emerged in the early stage of history was mainly the solar-powered devices of which the majority employed concentrating collector, only a few employed flat plate collector. The flat plate collector was invented in the later stage of 17th century, but it was actually developed and mass-scale production after 1960s. In the field of low temperature utilization of solar energy, the economic-technical performance of flat plate collector was far good than that of concentrating collector. In order to raise the efficiency and reduce the cost or to satisfy the special utilized needs, variable types of flat plate collector have been developed.

a.        If it is divided according to the actuating medium, there are air collector and liquid collector, which the latter has been utilized in large scale;

b.        If it is divided according to the material of plate core, there is steel plate iron tube, all-copper, all-aluminum, copper & aluminum hybrid, stainless steel, plastic and other non-metal collector.

c.        If it is divided according to the structure, there are tube and plate type, flat box type, tube wing type, heat pipe wing type, snake shape tube type collector, as well as plane reflecting mirror collector and reversible plate collector;

e.        If it is divided according to the cover plate, there are single or multi layer glass, fiber-glass-reinforced plastics, and high polymer transparent material and transparent thermal separation material collector.

Now the common used types in the world are all-copper solar collector and copper aluminum hybrid solar collector. For the combination of cooper wing and copper tube, high-frequent weld is generally employed in foreign country while actuating medium weld is employed in China. In 1998, the development of all copper high frequent weld collectors was succeeded in China. After digested and absorbed the cooper and aluminum hybrid production line, which was introduced from Canada in 1987, more than 10 production lines have been built in China.

In order to lessen the heat loss of collector, the cover plate material can employ hollow glass, polycarbonate sunlight plate and transparent beehive. But due to its high cost, it cannot be popularized at the short term.