The long-term reliability of photovoltaic modules is crucial to ensure the technical and economic viability of PV as a successful energy source. The analysis of degradation mechanisms of PV modules is key to ensure current lifetimes exceeding 25 years. This paper presents the results of the investigations carried out on the degradation mechanisms of a crystalline silicon PV installation of 2 kWp after 12 years of exposure in Málaga, Spain. The analysis was conducted by visual inspection, infrared thermography and electrical performance evaluation. By visual inspection, the most relevant defects in the modules were identified and ranked according to their frequency. The electrical performance was assessed by comparing the characteristic parameters of the individual modules, obtained by outdoor measurements at the start and end of the exposure period. The correlation of the visual defects and the shifts in the electrical parameters was analysed. The results presented show that glass weathering, delamination at the cell-EVA interface and oxidation of the antireflective coating and the cell metallization grid were the most frequently occurring defects found. The total peak power loss, including the initial light induced degradation, was 11.5%, which corresponded almost totally to a loss in short-circuit current.
This paper describes an experimental system developed in the photovoltaic laboratory at the University of Málaga (Spain) to measure the current-voltage curve of photovoltaic modules under outdoor conditions. The measurement is performed in an automated way by employing commercial instruments controlled by a computer using the GPIB standard. Several modules, selected sequentially through a set of relays, are biased by a four-quadrant power supply while a function generator synchronizes two multimeters in order to acquire voltage and current values. The measurement uncertainties were also estimated. The proposed method for synchronizing the voltage and current measurements ensures that these measurements are performed simultaneously; this means that the estimated uncertainty is lower than those obtained using other previously proposed methods. The main electrical parameters are estimated. A user-friendly application allows the user to configure several parameters, such as bias rate, voltage, and current limits and the number of points of the curve.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.