Analysis and modelling the reverse characteristic of photovoltaic cells

Models to represent the behaviour of photovoltaic (PV) solar cells in reverse bias are reviewed, concluding with the proposal of a new model. This model comes from the study of avalanche mechanisms in PV solar cells, and counts on physically meaningful parameters. It can be adapted to PV cells in which reverse characteristic is dominated by avalanche mechanisms, and also to those dominated by shunt resistance or with breakdown voltages far from a safe measurement range. A procedure to calculate model parameters based in piece-wise fitting is also proposed. The model has been applied to isolated crystalline solar cells measured at different conditions, and also to cells encapsulated in a conventional PV module. Good fitting has been found between the experimental and modelled curves. Evolution of calculated breakdown voltages with temperature is in accordance with avalanche theories.