Degradação induzida pelo potencial em módulos fotovoltaicos de filme fino

Abstract

Associated with the expansion of the photovoltaic sector, studies of the factors of losses in plants in operation have gained notoriety in the literature for the search for understanding the cause and solutions of the damages. The phenomenon of potential induced degradation (PID) has become notable in the last decade due to its negative influence on the performance of the photovoltaic module (PV) and mainly due to the difficulty of perception of the phenomenon, since it can be confused with the natural wear of the PV generator. In the universe of thin-film photovoltaic modules, other types of degradation are associated with the occurrence of PID, such as the electrochemical corrosion of the conductive transparent oxide (TCO) layer and the delamination of the layers. In addition, high environmental conditions such as temperature and humidity contribute as catalysts for the damage found in the assemblies. These elements, associated or not, affect the performance and reliability of the modules and the PV system in a short period of time, with significant signs of degradation ranging from 5 to 20% in the first year of operation. To avoid the occurrence of these loss factors, some procedures are adopted in order to guarantee the correct functioning of the PV system, such as galvanic isolation and functional grounding. This paper presents the PID assessment approaches and the other loss factors that are associated with the occurrence of the PID, exploring the degradation modes and analyzing the impacts on PV modules. Different topologies of PV systems were analyzed in the field, evaluating the PID detection methods and the efficiency of the technical solutions employed to prevent the PID from occurring. The theoretical approach and the practical results showed that the higher systems with a higher level of degradation than expected for the time of operation, possibly being associated with the absence of grounding and/or galvanic isolation and environmental conditions such as temperature, humidity and surface soiling. The results of the presented case studies indicate that the methodologies are effective even in the early detection of the phenomenon in thin film PV modules.