Many performance models exist for energy yield prediction. Most of the performance models use physical parameters determined from measured current density-voltage (JV) curves. However, there is no uniform parametrization method. Using the Karmalkar-Haneefa (KH) fit the physical parameters are obtained from one fitting equation. In addition, we investigate different linear parametrization methods and show that the parameters obtained from the KH model are comparable to those determined from two linear fits. Thereby, it is recommended to use a weighting factor of around 30 near the short circuit current for the KH fit to achieve better comparison with the linear fits. Thus, they can be used for performance models like the Loss Factor Model. For the analysis we used outdoor data for thin-film modules measured over one year in Cologne, Germany.