Thermodynamic Efficiency Limit of Bifacial Solar Cells for Various Spectral Albedos
We have adapted the Shockley-Queisser radiative flux balance model to investigate the influence of the spectral dependent albedo on the power conversion efficiency of bifacial solar cells. By taking the spectral albedo of the surroundings into account the optimal band gap becomes dependent on the type of ground-reflecting surface. Furthermore, we find that the maximum efficiency depends on the spectral albedo of the surroundings and that optimal cell performance cannot be assessed when only accounting for a spectrally-independent albedo. We predict that the power conversion efficiency for a bifacial silicon solar cell surrounded by green grass is an absolute 0.90% higher than expected from a wavelength independent albedo, and even 1.51% higher for white sand, with the spectral albedo model. Furthermore, we calculated spectral properties of antireflection coatings and we found that commonly used antireflection coatings in silicon solar cells provide good properties in order to accept back-scattered light from surfaces with different spectral albedos.