The favorable feed-in tariffs have rendered residential photovoltaic (PV) installations an attractive invest-ment for homeowners. Due to the restricted space availability as well as the regulatory limitations for theallowable installed capacity, optimization of the modules’ configuration becomes an important aspecttoward maximization of PV investment efficiency. In this study, a design methodology for the optimaldeployment of PV rows installed on flat-roofs is presented. The proposed methodology includes a photo-voltaic energy production model that takes into consideration the PV self-shading losses and their effecton the energy production, while the optimization process is performed by considering the effect of rowsgeometry on the energy output and on the net present value. These optimization problems are formulatedas constrained nonlinear programming problems and they are solved by using well-known deterministicmethods. The results from a case study illustrate the importance of the interaction between the PV panelsdimension and the geometry of the created PV rows with regard to optimal PV field designs under appro-priate constraints. Further and as far as financial parameters like investment cost and feed-in-tariff areconcerned, the results suggest that economic profitability is not always leading to energy maximizationand thus suitable designs must be applied.