Identification of early operational defects in photovoltaic modules: A case study of a 24.9 MWp solar PV system in Sumatra, Indonesia

Abstract

This study investigates early operational defects in a 24.9 MWp solar PV system located in Sumatra, Indonesia, within its first two years of operation. The primary objective is to identify key issues affecting performance, reliability, and energy output. Field observations revealed several critical defects, with hotspot formation being the most dominant issue. Hotspots, caused by partial shading, cell mismatches, or module damage, result in excessive localized heating, leading to material degradation and significant power losses. Additional defects included glass cracking (282 cases), primarily linked to hotspots and mechanical impacts, and 350 cases of junction box failures due to improper sealing, which pose long-term risks of moisture ingress and diode malfunction. Instances of foggy or discolored glass (delamination) were also identified, reducing light transmission and overall efficiency. Shading from external objects and self-shading between PV arrays exacerbated these problems. The study highlights that half-cut modules outperform full-cell modules in mitigating hotspot risks due to their lower current per cell and enhanced bypass diode configuration. Reducing the number of modules per string further minimizes hotspot severity. Recommendations include regular maintenance, shading mitigation strategies, and optimized system design to enhance performance and reliability. These findings provide valuable insights for improving large-scale PV system durability in real-world conditions.