Optical simulation of bifacial solar cells

Bifacial solar cells are used in several specialized photovoltaic system concepts, such as albedo collecting modules or in conjunction with upconverter materials. We present a simulation model for bifacial solar cells that allows the investigation of the rear side illumination of solar cells with great flexibility. We apply this model to bifacial test structures with different rear side reflectors and compare them to structures without rear side reflector. We consider the optical properties of planar cells, random pyramids only on the front side and random pyramids on front and rear side. Thereby, the optical simulation results show good qualitative agreement with test samples featuring the simulated reflection properties. Samples with texturing on both sides together with white paint as a rear side reflector show very good light trapping properties, but also other rear reflector configurations with diffuse scatterers, like e. g. PTFE, and specular reflectors like Ag mirrors show a comparable high increase in the photogenerated current density.