The aim of this work is to present an optimized model of metallic micro-grid used as anode electrode in organic photovoltaic devices excluding the use of expensive ITO (Indium Tin Oxide). A design of circular grid, adapted for silcon-based solar cells, is proposed here. A clear advantage of using the grid as opposed to ITO is the elimination of the absorptive losses the ITO adds to the structure. In order to optimize the collecting grid dimensions one must choose a compromise between the resistive losses, represented by the series resistance Rs, and the shadowing loss. Therefore, in order to find the best geometry of the grid, a comparative study has been done between the linear geometry and the circular one. Our results show clearly that the efficiency is enhanced when using the circular geometry. Copyright © 2010 John Wiley & Sons, Ltd.