A simple model to describe the dye sensitized solar cell (DSC) is presented in which simultaneous occurrence of diffusion and charge transfer processes, power loss due to inhomogeneous excitation resulted from absorption of the dye and the electrolyte, and power gain due to the direct excitation (not via dye molecules) of semiconductor particles are taken into consideration. About 35% and 2.2% decrease in power is estimated for the dye and the electrolyte absorption, respectively, while 2.9% increase of power is obtained by the direct excitation of TiO2 at maximum power point (MPP) under AM1.5 solar illumination. Some numerical results are also presented to demonstrate the influence of the material parameters for the cell characteristics. (C) 2003 Elsevier B.V. All rights reserved.