Thermal effect of micro-fin geometry on a silicon receiver for CPV cooling purpose

Temperature rising negatively affects all the photovoltaic technologies. This problem becomes particularly relevant for concentrating photovoltaic (CPV), where the sunlight density is increased up to thousands of suns and the exchange surfaces are inversely reduced. Furthermore, multijunction cells, most commonly used in CPV applications, intensely suffer the increasing in temperature. Several technologies, mainly active ones, have been tested so far to solve this problem. Micro- and nano-technologies can represent a cheap and effective passive solution for CPV cooling: in particular the application of a micro-fin array leads to a strong improvement of the exchange surface area. In this work, it has been developed onto a silicon backplate of a 4-cells CPV receiver: different designs have been developed and tested in a solar simulator and then the results have been compared to those of a flat silicon wafer. This paper investigates for the first time the effect of geometry of a micro fin array on natural convection on a silicon backplate of a CPV receiver, in order to minimize the thermal gradient between the solar cell and the cooling plate. It reports the improving in efficiency related to the application of a micro-fin array replacing a flat wafer. The correlation among the micro-fins geometric parameters (such as fins spacing and fins thickness) and the cooling efficiency of the array has been sorted out as well.