Photovoltaic Maximum Power Point Varying with Illumination and Temperature

Abstract

This paper presents the experimental results and discusses the track of the maximum power point on the current-voltage curve of a PV module due to changes of the illumination level and temperature. A time decrease of the voltage and simultaneous temperature increase during the initial stage of irradiation has been observed. Some practical implementation aspects of a maximum power point tracking unit, which match the current and voltage characteristics of the load to the PV module’s maximum power point automatically, are also discussed. A linear decrease of the maximum output power Pm with temperature increase has been observed and the temperature coefficient was derivate. Temperature coefficients for Voc, Isc, Vmpp, Impp, and ηPV have been determined for the photovoltaic module. Also the radiation-rate coefficient at constant temperature has been calculated.