Abstract
In this paper, performance losses and correlated degradation of five different PV systems representing five different PV technologies are investigated. Here, we describe the overall performance loss of a PV system in greater detail to better understand which underlying reasons trigger the performance decline of the investigated PV systems. The plants were installed in 2010, and almost 12 years of system operation are considered. Based on best practices developed by the IEA PVPS Task 13, the linear performance loss rates of all PV systems have been calculated. The results are correlated with corresponding nonlinear performance losses, voltage and current evolution, I-V curves and infrared and luminescence images captured in the field. Overall, it was shown that crystalline-based PV systems experience a lower overall performance loss compared to thin-film systems. The losses in crystalline systems stem from cell mismatches within modules and gradually developing degradation modes such as snail trails and cell cracking. The thin-film systems under investigation are subject to higher performance loss rates, (most) likely triggered by a degradation of the active PV material. Furthermore, glass-glass thin-film modules are additionally exposed to physical stresses by the mounting clamps leading to cracked glass, which may jeopardize the mechanical integrity of the modules.