Aerodynamics for CPV: Investigating the efficiency of using air fairings on solar trackers

The biggest advantage of CPV systems over other PV technologies is the efficiency of converting solar irradiation into electrical energy. Though, this advantage can be substantially overshadowed by a number of factors, which affect CPV systems during their operational lifetime. Wind loads is the factor that can greatly reduce the accuracy of sun tracking, put additional strain on elements of a frame and motor gears, and at critical values can even be a reason of destruction of an entire system. Unlike the most common approach of making the tracker more rigid, we decided to reduce wind loads instead. Achieving this for CPV systems requires reduction of their aerodynamic drag. In the present paper we describe a very effective and cost-efficient way to accomplish this task. The idea is to implement lightweight plastic fairings along a perimeter of a CPV system. Experiments with a model of a CPV module with and without such fairings were carried out in a wind tunnel, showing that substantial reduction of a drag coefficient and hence wind loads is achieved for stow position and elevation angles typical for hours during which the most energy is produced at major installation sites. Computer 3D simulation of air flow around the CPV module has shown that otherwise turbulent flow around module becomes laminar after attaching air fairings. Laminar flow along an optical surface of CPV modules could reduce soiling and improve convection, thus improving heat transfer from surfaces of a module to environment.