From long-term detailed measurements of several PV modules of all commercialized technologies, this work aims to analyze the results of the “standard” one-diode model, and suggests some modifications for improving it, especially for amorphous, microcrystalline and CdTe modules. We found that for any module an exponential behaviour of the shunt resistance parameter should be taken into account. We identified two other corrections (recombination losses and spectral correction) in order to improve the modelling of amorphous technology modules. These improvements have been implemented in the PVsyst software developed at the University of Geneva.