Chronological development of innovations in reflector systems of parabolic trough solar collector (PTC) - A review

The parabolic trough collector (PTC) technology is the most mature and cost-effective of solar thermal technologies. Given its importance in the use of solar power for electricity and industrial heating, this review presents a chruonological review of important innovations and improvements in reflector structure design and tracking system over a century of development. The fastest evolution is in the support structure of the PTC which has evolved from the old torque tube to the modern space tube. The space tube design is considered better for cost effective performance. The tracking systems have evolved from the conventional light-and-shadow sensing feedback loops to modern image-processing artificial-intelligence based systems with tremendous increases in tracking accuracy. This work also touches on reflective and structural materials. There has not yet been found a material to beat glass reflectors for specular reflectivity and durability. Considerable effort has gone into developing metal/polymer sheet reflectors, but their durability under cyclic weathering conditions is an open question. Similarly, there have been very few alternatives tried for steel as a support structure and most of these have experimented with aluminum. Only two types of actuators have been investigated: the geared motor and the hydraulic so far, and the geared motor has been the most favored. The optimization of all the components namely the reflector structure, tracking system, and reflector can lead to a design of PTC at a cost of 75–100$/m2 of aperture.