This paper shows a methodology for the assessment of the photovoltaic potential in urban areas using Google Earth™ tool that provides either satellite images of the roofs of buildings or their number of floors by means of the Street View function. The applicability of the methodology has been tested on a selected urban area of the city of Palermo in the South of Italy. After classifying roofs according to the shape, orientation and pitch of buildings with different morphologies, the share of energy generated by the installable PV systems was evaluated with regard to the number of floors. Moreover the coverage of the electricity demand was investigated on the basis of the consumption of electricity of the households. The results of the energy assessment have been screened considering the economic feasibility of grid-connected photovoltaic systems. The proposed methodology permits to select a threshold number of floors of the buildings in correspondence of which the PV system that may be installed, and the consequent production of electricity, may not recover the costs for installation and maintenance of the system. This aspect has also been analyzed by considering the main factors that influence the computation, such as the mismatch between generated and consumed electricity and the shading effects due to the surrounding obstacles. The methodology could also be used to assess the effectiveness of the national incentives to support the diffusion of the PV systems in the short term.