How do Solar Collectors Function?

Solar collectors are also known as solar thermal collectors, systems which are used to collect and absorb solar energy and convert it into a more usable form. The most popular type of solar collectors are those found in domestic water heating systems, although solar collectors are also regularly used in industrial power generation facilities. While the term solar collector can be applied to solar cells and photovoltaic panel technology, it is much more often used to describe the method of generating either heat or electricity through the direct application of solar heat. There are a number of different types of solar collectors in use around the world, with different categories of systems working in different ways. The two basic categories of solar collectors that are used for heat generation include concentrating and non-concentrating systems, and those for electricity generation include a variety of troughs, dishes, and tower systems.

Heat and Electricity

Concentrating and non-concentrating solar collectors function is a similar way, although in non-concentrating devices the collector area is the same as the absorber area. Two of the most common devices used in domestic water heating applications include flat plate collectors and evacuated tube collectors. Of these, flat plate collectors are the most common, consisting of a dark flat plate absorber, a transparent cover, a heat-transport fluid, and an insulating backing. Evacuated tube collectors use special evacuated heat pipe tubes (EHPTs) which are composed of evacuated glass, with absorber plates fused to heat pipes. A special transfer fluid is used to transfer the heat, and a vacuum surrounds the outside of the tubes to reduce heat loss through convection and conduction. This vacuum means that evacuated tubes are generally more efficient than similar flat plate technology, especially in colder climates.

While these kinds of thermal solar collectors are most commonly used in domestic applications, there are also solar collectors that generate electricity found in solar power plants around the world. Parabolic troughs and parabolic dishes are regularly used for this purpose, where light is concentrated to a focal point and transferred to boilers in a power station. Solar power towers are also used in some situations, using mirrors to focus sunlight, collect heat, and transfer energy to a power station below. Through the absorption and distribution of solar energy, solar collectors can have a big impact on the reduction of fossil fuel resources and the creation of a sustainable energy future.