In this study the geometrical optimization of monolithically integrated solar cells into serially connected solar modules is reported. Based on the experimental determination of electrodes0 sheet and intermittent contact resistances, the overall series resistance of individual solar cells and interconnected solar modules is calculated. Taking a constant photocurrent generation density into account, the total Joule respectively resistive power losses are determined by a self-consistent simulation according to the 1-diode model. This method allows optimization of the solar module geometry depending on the material system applied. As an example, polymer solar modules based on ITO-electrodes and ITO-free electrodes were optimized with respect to structuring dimensions