Improving PV Array Output During Partial Shading using Voltage Balancing Approach

Inhomogeneous insolation on a solar PV plant due to cloud, nearby construction, tree branches etc. reduces its power output significantly. Further, multiple peaks in power-voltage characteristics of the PV array are also observed due to partial shading, which calls for sophisticated and costly MPPT controller to make the the array operate at its global MPP. However, the enhancement in array output using global MPP is also limited by the array interconnections. This leaves scope for further improvement in array power output. In this work, a voltage balancing technique using DC-DC converters is developed to improve the array power output during partial shading. The results of simulation carried out to validate the proposed method for different shading level and pattern show its effectiveness in improving the power output. In addition, a case study on constant power load (CPL) using a PV-battery system demonstrates that the proposed strategy can also double as a demand-response controller for a PV array to feed CPL.