A revised method to evaluate parameters of solar cell from current-voltage characteristics, under illuminated or non-illuminated conditions, was described. The series resistance(Rs), the shunt resistance(Rsh), the ideality factor(n), and the reverse saturation current density(J0) were extracted using the two diode circuit model from selected regions of the J-V curves. Using the presented model, more parameters with higher fitted precision have been extracted from experimental J-V curves of a CdS/CdTe thin film solar cell than using a single diode circuit one.