Abstract : This chapter deals with a simplified, meaningful thermal model to calculate photovoltaic (PV) cell temperature, which is of utmost importance in determining the electrical energy efficiency of PV modules. This model, which has been applied to standard PV modules (or Glass/Backsheet solar panels), takes into consideration ambient temperature, incident irradiance, and wind speed. A complete experimental database was built to calibrate this model. The results of the thermal modelling provide a heat transfer coefficient law, which may be implemented in a PV simulation tool. Two key elements of this approach can be highlighted. The results enable better calculation of the electrical energy production of PV modules and help to predict the energy efficiency of PV units.