Characteristics of Solar PV Array under Partial Shaded Conditions

Increasing prices of fossil fuels and awareness of global warming have drawn attention towards the use of Solar Photo Voltaic Cells as an alternative source of electric power. Experimental determination of voltage-current characteristic of a solar panel is required for its simulation and setting the parameters of the circuit for extracting maximum power. An attempt to determine such a characteristic by connecting a variable resistance across the panel and measuring the voltage and current by meters is not successful all the times due to varying cloud positions and temperature during the experiment. A method to quickly draw the characteristics and recording the result using electronic load has been presented in this paper. As a single cell produces voltage around 0.7V only, a number of cells are connected in series forming a Solar Photo Voltaic Array (SPVA) to produce voltage levels of practical use. For a practical SPVA spread over large area, it is difficult to maintain uniform insolation on all the cells at all times. Such a problem may arise due to passing clouds, shadow caused by neighboring buildings, trees etc. In this paper, characteristics of three solar panels receiving different insolations and connected in series have been drawn using fast electronic load. A method to add the characteristics of individual panels to obtain the combined characteristics has also been presented.