Equivalent circuits for simulating irregular PV arrays under partial shading conditions

Modeling and simulation of photovoltaic (PV) systems are open research areas since I-V and P-V curves are commonly required to analyze the performance of PV installations. To obtain such curves commercial software packages can be used, however the connection type and size of the PV array may cause large simulation times. To overcome such an issue several techniques based on analyzing the inflection points have been proposed to model the PV array with the aim of reconstruct accurately the required electrical curves. However, such analysis has been applied only for series-parallel (SP) configuration, which is just one alternative to connect PV arrays among several other regular or irregular options. Therefore, a more general approach is needed. This paper presents an approach to obtain the characteristics curves for any PV array, regular or irregular, by extending the inflection points analysis. Then, the calculation of the PV array electrical curves is simplified by using equivalent circuits within the intervals defined by the inflection points. Such a procedure is based on defining which modules become active due to the behavior of the bypass diodes. Finally, the proposed approach enables to analyze any PV array without requiring long electrical simulations. The solution was validated by means of simulation results obtained in Matlab®.