The same equation was derived from two different impedance models based on the quite different physical descriptions proposed by Kern et al.(1) and by Bisquert.(2,3) Reliable values of the parameters relating to electron transport in dye-sensitized solar cells can be determined from measured spectra by electrochemical impedance spectroscopy when careful analysis of the measured spectra is done based on the classification and clarification of the same impedance equation consequent from the two models. The requisites for making highly efficient dye-sensitized solar cells were proposed.