Graphene as a pre-illumination cooling approach for a concentrator photovoltaic (CPV) system

Abstract

The concentrator photovoltaic (CPV) system has a high potential in increasing the power output, propelling further the concentration ratio generating excessive heat that significantly deteriorates the solar cell efficiency and reliability. To thoroughly exploit graphene as a pre-illumination cooling technique for a solar cell, we experimentally characterized screen printed graphene coating (GC) physicochemical characterizations to observe the attenuation of light across a wide wavelength range with different GC thicknesses on a low iron-glass. The thermal and electrical characterizations were further executed to observe the performance of GC on a concentrated CPV system. Based on these comprehensive experimental characterizations, the concept of utilizing graphene as a neutral density (ND) filter for focal spot CPV system is shown to reduce the device temperature significantly by 20% and 12% for GC6.3 (6.3 μm thickness) and GC2.2 (2.2 μm thickness) in comparison with the infrared filter, respectively. It has been observed that GC6.3 increased the cell efficiency by about 12% at 8 suns compared to the base case at 400 W/m2 producing 7 suns. It has been ascertained that the introduction of graphene as the ND filter component improved the solar cell efficiency instead of just reducing the geometrical concentration ratio. Further, even the most susceptible single-junction solar cell under a concentration ratio of 20 suns with no cooling aid has shown an excellent cell efficiency. Therefore, our approach envisages its application for non-CPV and high and ultrahigh CPV system incorporated with a triple-junction solar cell eliminate the use of external heat sinks or other cooling arrangements.