Geometrical assessment of solar concentrators using close-range photogrammetry

Solar concentrating technology uses defined reflective surfaces to concentrate beam solar radiation into a receiver through a heat transfer fluid in circulation (i.e. thermal synthetic oil, water/steam, air, molten salt, etc.). These fluids are heated up by the concentrated solar radiation and the thermal energy collected can be used, among other things, to provide thermal energy to industrial processes. Reflective surfaces require a high geometrical precision in order to concentrate the solar radiation onto the receiver, minimizing radiation losses around the receivers. Close-range photogrammetry has been revealed as a highly efficient and precise technique to evaluate the geometrical assessment of solar concentrators. And this task has become essential on the evaluation of the different concentrators used nowadays on solar thermal systems. At the Plataforma Solar de Almeria, a set of methods and algorithms based on close-range photogrammetry has been developed on the last years. These methods allow us to evaluate the geometrical quality of solar concentrators. The application of these techniques to different concentrators prototypes, permits us to determine their geometrical, optical and energy behavior as well as to detect improvements on their design. This paper includes the analysis performed to a small parabolic solar concentrator designed for industrial process heat applications. (C) 2012 The Authors. Published by Elsevier Ltd.