Shading effects in back-junction back-contacted silicon solar cells

One of the most often mentioned advantages of back-junction back-contacted silicon solar cells is that this cell structure has no shading losses, because metallization fingers and busbars are both located on the rear side of the solar cell. However, this is only true if only optical shading losses are regarded. In this work electrical shading losses due to recombination in the region of base busbar and fingers are analyzed using two-dimensional numerical device and network simulations. The base doping dependence of these effects is investigated as well as the influence of the rear side passivation. The results of the simulations are compared with EQE maps of back-junction solar cells. The influence of the busbars is quantified and the influence on the overall cell performance is discussed.