Humps in dark I-V-curves-analysis and explanation

Analysing a large number of dark and light I-V curves of different kinds of solar cells, the author noticed two main discrepancies between the measured curves and the two-diode model which was used for the analysis: the value of the diode quality factor of the recombination current, n₂, more often than not differs from the usually assumed value of n₂=2; and some I-V curves show an additional structure (“hump”) in the voltage range corresponding to the recombination current which cannot be described by varying the value of n₂. In this work, the author gives a quantitative analysis and explanation for the observed humps. Starting from their mathematical description, the other forms of deviation from the usual two-diode model are derived