Assessment of energy and economic effectiveness of photovoltaic systems operating in a dense urban context

A methodology that permits testing the level of integration of the photovoltaic technology in urban areas is presented. The percentage of coverage of the electricity demand of grid-connected photovoltaic systems installed on the roofs of buildings was investigated in a district of the city of Palermo (Sicily). After classifying roofs according to their shape, orientation and pitch by means of satellite images provided by Google Earth, the ratio of the productivity of the PV systems and the consumption of electricity of the households was analysed. The results of the energy assessment have been screened considering the economic feasibility of grid-connected photovoltaic systems: the energy produced by the PV systems whose economic analysis showed disadvantageous values of NPV or IRR was rejected. As a result, it can be concluded that the size of the PV system that may be installed corresponding to the number of floors, and the consequent production of electricity, does not recover the costs for installation and maintenance of the system.