A research team from the Fraunhofer Institute for Solar Energy Systems ISE has evaluated over 70,000 power measurements on photovoltaic modules that have been carried out in the institute's calibration laboratory, CalLab PV Modules, since 2012. In the process, the researchers found that since around 2017, the negative discrepancy between the performance data of the PV module manufacturers and the research institute's measurement results has been increasing. Until 2016, more power was measured in the laboratory on average than was promised by the manufacturer. Since then, a negative trend has emerged, particularly in the years 2020 to 2023, leading to an average power reduction of about 1.3 percent. The latest data from 2024 show a slight turnaround.
more info