Concentrated solar power (CSP) utilize lenses and mirrors in order to focus solar irradiation on a small area. The concentrated radiation can be applied to generate electricity indirectly. The absorbed heat from solar irradiation is used in thermodynamic cycles in order to produce electricity. These systems are able to generate electricity even in the absence of sun which can be enumerated as their main advantage compared to solar power technologies. This possibility can be happened by integrating energy storage systems such as thermal storage tank to save the extra amount of thermal energy in the daylight for being used in the periods which sunlight is not available.
Among the various types of CSP systems, parabolic-trough collectors have the highest market share which is approximately 90%.
A parabolic trough concentrator (PTC) utilizes the line focus technology for the CSP. PTC consists of collector with long parabolic trough and a pedestal as support of the collector. This technology focuses solar irradiations on its focal line. A receiver is located there which absorb the heat. High absorptance material is utilized to coat the receiver. It is surrounded by a tube which is made of glass. In order to decrease heat losses, vacuum status is created between the tube and receiver. Vacuum plays key role in receiver insulation and loss of vacuum can cause four times higher heat loss. Using lesser components and leakage-free glass cover, vacuum leakage can be prevented.
Schematic of parabolic trough collector
Parabolic trough reflector
The working temperature of PTC is wide, in range of 100 to 400°C, which makes it applicable for several applications. PTCs are categorized based on their working temperature. PTCs work in temperature range between 300 and 400°C are mainly applied for power generation while the ones operate in the range of 100-250°C are used for heating purposes.