An Embedded Reconfiguration for Reliability Enhancement of Photovoltaic Shaded Panels Against Hot Spots

摘要

The reliability of conventional photovoltaic (PV) structure in shaded situations can undergo different issues related to internal and external conditions. The internal condition accounts for the inhomogeneity of the properties of electrothermal cells, while the external conditions connote optimal power maximum tracking techniques and protection circuit limitations. This article proposes a new technique to improve the reliability of shaded panels, considering the internal and the external issues. Our study begins with an extensive analysis to assess the vulnerability of PV cells to second-quadrant thermal stress and operational limits of bypass diode protection against hot spot. Consequently, we proposed a new system that concurrently operates with the maximum power extraction process to assist bypass diodes with hot-spot protection. This proposition results in a reconfigured panel with both a local detection circuit that defines the conduction states of bypass diodes and additional mosfets that switch shaded subgroups. In this article, an algorithm was developed that is capable of controlling the optimal maximum operation point tracking with an on-demand deployment of the protection mosfets, using the signals provided by the local detection circuit. A set of experiments were carried out in order to demonstrate the capability of the proposed method to prevent hot-spot damages over all shading rates and operating points. The novelty of the proposed approach is its low cost of implementation as well as its simple and efficient design. Therefore, it has the potential to be easily integrated along side existing infrastructure and maximum power point tracking algorithms.