Photovoltaic panels are prone to degradation after long outdoor exposure, which can be manifested in multiple forms. This phenomenon also causes an alteration of the panel's parameters. In this work, a heuristic search methodology based on the Nelder-Mead algorithm is applied in the estimation of photovoltaic panel parameters. Modifications that improve the performance of the method are also presented. The results of this modified Nelder-Mead algorithm are compared with the results of the classical method. A sensitivity analysis towards additive noise and ADC resolution is performed.