Abstract Photovoltaic (PV) modules convert part of incident solar energy into electrical energy for commercial applications, with the rest being transferred to heat energy. The modelling of PV modules plays an important role in the fault diagnosis of a PV array. The object of this paper is to develop a parameter based model of a PV module. This model is sequentially coupled with an electrical model and energy balance equation. In order to establish the parameter based model, key parameters including the total effective solar energy, total heat exchange coefficient and ambient temperature are calculated from two working points on PV module along with the corresponding temperature from a thermal camera. Using the developed model, a fault diagnosis method based on the model is illustrated. Finally, model validation is carried out by the experiments.