The European agreements regarding energy policies require an improvement of energy efficiency and the optimization of the exploitation of renewable energies available in cities. Solar energy is normally the most abundant resource in cities, and buildings’ façades and roofs are the urban elements with a highest exposition to this type of energy. Photovoltaic distributed generation and intelligent networks make the net mettering system a very efficient and sustainable solution. In this paper, a study on parameters and indexes to select those façades which are more suitable for the installation of photovoltaic panels, according to its capacity of solar radiation exploitation, is presented. For that purpose, different irradiance models have been considered introducing some improvements through the term “Sky View Factor”, which represents the portion of sky vault seen for a particular point of a façade. Furthermore, an Utilizability factor for façades has been defined and to the analysis of the energetic potential of a block of buildings situated in Stuttgart (Germany). The results show that the preselection of façades for the installation of panels through the proposed factor optimizes the installation, maximizing its profitability.