Degradation of polycrystalline Si solar cell efficiency with increased incident optical power — Experiments and theory

In this paper we discuss our experimental data obtained for several Si PV cell samples. From the I-V curves measured under various optical irradiance levels, we extracted the fill factors and the series and shunt resistances of the solar cells. For some of our samples, the solar cell efficiencies decrease even at illuminating power densities less than 1 Sun due to reductions in fill factors. Theoretical analysis suggests the reason for the observed dependences of PV cell circuit parameters on optical injection can be defect-mediated carrier recombination.