Multi‐pronged degradation analysis of a photovoltaic power plant after 9.5 years of operation under hot desert climatic conditions

Abstract

Long‐term reliability assessment of photovoltaic (PV) modules is key to ensuring the economic viability of PV systems. This paper presents a multi‐pronged performance degradation analysis of a 62.1 kWp solar PV power plant after 9.5 years of operation. For this purpose, various diagnosis techniques, namely, visual inspection, infrared thermography (IR), ultraviolet fluorescence (UVFL) and current‐voltage (I‐V) characterization, have been performed to evaluate the performance and degradation of the solar PV power plant. The visual characterization results show that the PV strings are affected by different mechanisms with different degrees of occurrences. The degradation mechanisms observed and the level of occurrence among the modules were found to be, encapsulant discolouration (100%), degraded frame adhesive (57%), degraded junction box adhesive (39%), snail trails (30%), burn marks (3%), cell cracks (2%) and delamination (0.4%). Although discolouration of the encapsulant was the most common possible degradation mechanism observed, the main causes of the power loss were snail trails and cracks in the PV cells. Furthermore, the IR thermography and UVFL analysis provided better understanding on snail trails phenomenon and crack mechanism on the affected PV modules. Besides imaging techniques, to assess the electrical performance of the system, we performed current‐voltage (I‐V) and power‐voltage (P‐V) characterization of the entire PV plant from which the degradation rates of the electrical parameters were determined. Our results show that the degradation rates for the maximum power and the fill factor are 0.84%/year and 0.66%/year, respectively, over the operating period of the installation. The estimated maximum power degradation rate for this installation could be considered as a realistic degradation rate for PV modules installed in harsh and hot desert climatic conditions. Additionally, our work has raised doubts about the validity of the warranties proposed by the manufacturers.

A Review of Photovoltaic Module Failure and Degradation Mechanisms: Causes and Detection Techniques

“…Furthermore, junction boxes can degrade at a faster rate when exposed to large variations in ambient temperature during the year. Daher et al [154] evaluated the reliability of a 9-year PV system (270 modules) installed off-grid that was expected to produce 62 kW in Ali Adde town, Djibouti. The PV system was exposed to the town's high temperatures with dramatic variation from winter (average temperature is 26.7 • C) to summer with an average of 38 • C. Out of 270 modules, 39% were diagnosed with adhesive junction box failure.…”

Outdoor Degradation Analyses of Six Different Aged Photovoltaic Module Technologies Under the Arid-Steppe Climate Condition

“…For PVUSA under PTC conditions: 0.057 ± 0.68%/year for DC power and 0.085 ± 0.68%/year for AC power. Also Daher et al (Daher et al 2023)release a study at 2023 given an information about degradation rates of different area for different module technologies. According to this study, the degradation rates are in range between 0.03 % /year (Singapore, c-Si) and 6.5 %/year (Ghana, m-Si and p-Si).…”