Shading Effect to Energy Withdrawn from the Photovoltaic Panel and Implementation of DMPPT Using C Language

Abstract

At first, this paper aims to study the effects of partial shading of photovoltaic (PV) panel without bypass diode, in order to present the hot-spot problem which can cause permanent damage to the panel, and with bypass diode that actually protects the panel against the hot-spot phenomenon. A PSIM simulation model that represents a PV panel under shading has been used to do this and the results are presented in this paper. And then, we benefit from the component provided by PSIM (C block) in order to code the maximum power point tracking algorithm (MPPT) using embedded C language so as to operate the PV panel at maximum power point (MPP). One of most precious advantages of this method is that once the MPPT is implemented using C block it can be applied in digital devices, because C language is portable and independent of the machine. The algorithm used is based in Perturb and observe method and it represents a good performance in terms of response time (0.005s) and efficiency (98.99%). However, we demonstrate that this method can fail to follow the real MPP since multiple maxima can exist on the PV power curve under partial shading (global MPP and local MPP). Finally, to solve this problem, the distributed maximum power point tracking (DMPPT) method is used.