Types of installations

There are two types of solar thermal plants, depending on the kind of solar collector used.

• Flat plate collectors: it is the most common type of solar thermal collector. Generally all consist of a flat-plate absorber, which absorbs the solar radiation, a transparent cover that allows solar energy to pass through but reduces heat loss from the absorber, a heat-transport fluid (air, antifreeze or water) flowing through tubes to remove heat from the absorber, and a heat insulating backing.



• Evacuated tube collectors: These collectors have multiple evacuated glass tubes which heat up solar absorbers and then solar working fluid (water or an antifreeze mix) in order to heat domestic hot water. The vacuum within the evacuated tubes reduce convection and conduction heat losses, allowing them to reach considerably higher temperatures than most flat-plate collectors.

In the following table are compared the average efficiencies of the two different types of collectors.