An analytical approach to study partial shading effects on PV array supported by literature (original) (raw)

2017, Renewable and Sustainable Energy Reviews

This paper presents the effects of partial shading on PV arrays. The characteristics of PV array under various shading patterns are modeled in the form of current-voltage graphs. The analysis of these graphs leads to several critical observations, which are summarized in five statements. Based on these statements, two hypotheses are presented: 1) irrespective of any partial shading pattern, maximum number of local maxima in a PV array is equal to the number of series connected modules in a string, 2) number of local maxima in a PV array is equal to the quantity of open circuit voltage values (excluding last value) around which bypass diodes of the shaded modules become forward biased plus 1. Finally, both hypotheses are verified with the help of simulation results. Other than that, our findings provide exact information about the shaded PV module in an entire PV system. This study strengthens not only the theoretical knowledge of shading phenomena but also helps exploring the partial shading effects on PV array without any aid of software, advanced techniques or practical systems. • Since these models are based on complex intelligent schemes [24-26], therefore, for user convenience, most of these research articles provide the working principle of the models in the form of flowcharts. Nevertheless, the user needs to understand the flowchart and other basic parameters of complex techniques to run these models. • These models can be implemented in C/Matlab software [27,28]. Therefore, basic knowledge of these software is mandatory for the user. Moreover, a computer platform is required. Even when the user implements all these steps, the conceptual understanding of PS effects on PV array is limited. It is because of the reason that the user will get the I-V curve of PV array, which indeed gives the information of number of LMs present on the I-V curve, but doesn't indicate that which strings or modules in a PV array are responsible for these LMs. On the other hand, some researchers explore PS effects using practical PV systems [29-31]. Hence, a simple and comprehensive analysis regarding the PS effects on PV array is limited in literature.