Understanding Photovoltaic Module Degradation: An Overview of Critical Factors, Models, and Reliability Enhancement Methods

Abstract

Photovoltaic (PV) modules, though reputed for reliability and long lifespans of 25-30 years, commonly experience gradual performance degradation influenced by varying environmental factors. This literature review explores the degradation of PV modules through in-depth analysis of failure modes, characterization techniques, analytical models, and mitigation strategies. A range of failure modes seen in PV modules are discussed, including interconnect breakage, cell cracks, metallization corrosion, delamination, ethylene-vinyl acetate (EVA) discoloration, Potential-Induced Degradation (PID), Light-Induced Degradation (LID), and other. Environmental stresses like temperature, humidity, ultraviolet (UV) radiation, and dust accumulation play significant roles in accelerating almost all degradation modes. Dust is a crucial factor in Middle East/North Africa (MENA) regions. Studying degradation modes under real-world conditions remains challenging, requiring extensive field testing to examine defect frequency, evolution rate, and impacts on energy production. PID is a major degradation mode requiring modeling and correction techniques to improve PV efficiency and lifespan. However, PID models are often limited to specific conditions, posing applicability challenges. Characterization methods like visual inspection, current-voltage (I-V),various imaging methods, and resonance ultrasonic vibrations (RUV) enable effective evaluation of degradation effects on module properties. Analytical models facilitate study of particular degradation modes and prediction of lifetimes under diverse conditions. Key factors influencing PV degradation include weather variations, materials quality, design parameters, PID, and hot spots. Protective coatings, encapsulation improvements, and module cleaning help mitigate degradation and prolong lifespan. A comprehensive understanding of mechanisms through integrated experimentation and modeling is critical for performance improvements. By reviewing major degradation phenomena, characterization techniques, analytical models, and mitigation strategies, this study promotes PV durability and sustainability. Significant knowledge gaps persist regarding module behavior under varied climate conditions and synergistic effects between different degradation mechanisms. Extensive field testing across diverse environments paired with advanced multiphysics modeling can provide valuable insights to guide technological enhancements for robust, long-lasting PV systems worldwide.