This work presents, for the first time, extensive spectral response measurements of bifacial solar cells before and after electron and isotropic proton irradiation, both from the front and back faces. The dependence of the photogenerated current on the total light irradiance is analysed and discussed. The spectral response measurements are correlated with the spatial distribution of the induced defect density.
Two main topics are covered in this work. First, a complete quasianalytical model for bifacial solar cells is presented. Features of this model include heavy doping effects in front and back emitters, bifacial illumination, variable injection levels in the low doped base regions, and radiation induced defects both by electrons and protons (isotropic or directional). Secondly, extensive experimental results concerning the photovoltaic characteristics of bifacial cells after electron and proton irradiation are presented. Specific techniques for bifacial cell measurement under bifacial illumination are also described. Finally the capabilities of bifacial cells for low earth missions is discussed.