Evaluation of by-pass diode and DMPPT under partial shade condition of photovoltaic systems

Partial shade and mismatching among PV modules in a PV system are common phenomenon caused by trees, passing clouds, manufacturing tolerances, etc. Due to mismatching/partial shading, the P-V characteristic curve usually comprises of multiple local and a global peak. To extract the maximum energy, usually three techniques are proposed. The first one and widely used is to use central MPPT technique (use of by-pass diodes) to track the global peak, the second is use of distributed per module/ sub-module MPPT (DMPPT) and the third is reconfiguration of modules in an array. The second and third options can increase the extracted PV power. However, the increase in cost and implementation complexity and control are some of the challenges of the techniques. In this paper, performance evaluation of by-pass diode and DMPPT per module technique for PV system under partial shade has been done.