OICC Press International Journal of Energy and Environmental Engineering 2251-6832 7 2 (June 2016) 2016 04 30 Efficiency analysis of PV power plants shaded by MV overhead lines 10.1007/s40095-016-0208-2 EN Alberto Dolara Dipartimento di Energia, Politecnico di Milano, Milan, IT George Cristian Lazaroiu Department of Power Systems, University POLITEHNICA of Bucharest, Bucharest, RO Emanuele Ogliari Dipartimento di Energia, Politecnico di Milano, Milan, IT Journal Article 2016 04 30 Abstract This paper deals with the occurrence of hot spot phenomena in photovoltaic (PV) systems under partial shading caused by objects on some parts of the modules. An interesting case of diffuse shadows is determined by overhead distribution lines whose path crosses or are in the proximity of the PV power plants. Investigating the impact of these shadows on reducing the power production of PV or on damaging the PV modules as the modules’ temperature is increasing, is of high interest. At the SolarTech laboratory of Politecnico di Milano, the conditions for hot spot phenomena occurrence due to the overhead lines shading the PV cells were reproduced. Two experimental campaigns were carried out to investigate the current–voltage and power–voltage characteristics, and the energy production. In each experimental campaign, the built shading structure was considered fixed and different shading conditions were created based on the natural displacement of the sun. The hot spot phenomena was revealed on a field PV installation in Italy, caused my medium voltage overhead lines shading the PV cells, using infrared imagery.