Validation of a multi-exponential alternative model of solar cell and comparison to conventional double exponential model

The modeling of a solar cell is useful for any operation of efficiency optimization or of diagnostic of the photovoltaic generator. Usually, a solar cell is represented by an equivalent electrical circuit which the physical parameters can be determined experimentally from the (current-voltage) characteristic. For the classical two exponential model, the equivalent circuit contains two diodes, a photogenerated current, a series resistance and a conductance. In the alternative model proposed in [5-7], this circuit is substituted by a Thevenin generator and two resistances in series with each of the two diodes. In this study, we express analytically the physical parameters of the alternative model depending to those of the classical model, considering the equivalence of the two circuits. It is then possible to reduce the number of equations and extract physical parameters easily. The reliability of both models is evaluated by comparing them to experimental (current-voltage) characteristics of a real solar cell.