Bypass diode function in solar panels and their diagnostic methods

Abstract

The purpose of the paper is to indicate the importance of measures on diagnosis and maintenance of solar panel bypass diodes. The study involves the theoretical analysis of information data on bypass diodes and their troubleshooting. Consideration is given to solar panel defects arising from faulty bypass diodes. The study uses computer simulation in PVSYST program, simulates bypass diode faults on YL-250P-29b solar panel and performs bypass diode diagnostic by the methods of short-circuit current analysis at partial shading and idle voltage parameter under normal conditions. It is determined that the methods of thermal imaging diagnostics (including those using a drone) and visual inspection are not accurate troubleshooting tools for faulty bypass diodes. The analysis methods of short-circuit current at partial shading and the idle voltage parameter under normal conditions are applicable for small solar power plants. They also can be used for the diagnosis of bypass diodes of solar cell arrays assembled from spare parts as well as for tools and devices at large solar power plants. The method of thermal imaging diagnostics using an external source is recommended to use for full fault diagnosis of bypass diode breaks in large solar power plants.