In this paper, an optimized method on the basis of polynomial fitting and Lambert W function is presented to extract parameters from the current-voltage (I-V) characteristics of commercial silicon solar cells. Since the experimental outcomes have significant impact on the precision of extracted parameters, polynomial fitting serves to overcome the obstacles of measurement noise in this method. The Lambert W function is employed to translate the transcendental equation into explicit analytical solution. Comparing with the as-reported parameters of a silicon cell and a plastic cell in the previous literature, the interesting outcomes demonstrate that the proposed approach is helpful for obtaining precise extracted data. This is further showed by the good agreements between the fitted I-V curve and the experimental results of a commercial monocrystalline silicon solar cell. Moreover, full extracted parameters of a badly shunted multicrystalline silicon solar cells before and after laser isolation process are conducted and investigated, the good fitting results finally show the validity of this attempt again. (c) 2010 Elsevier Ltd. All rights reserved.