Requirements for testing, documentation and evaluation of anomalies in photovoltaic module backsheets
06/2021 – 05/2023
Prof. Dr. Ralph Gottschalg
BMWK | 03TN0025
In recent years, reocurring inspections of photovoltaic (PV) systems have shown a significant increase in module failures triggered by the polymeric backsheets. Irregularities in polymeric backsheets, such as chalking, delamination, cracking or browning, usually results in degradation of the electrical isolation and increases the risk of electrical shock.
Existing standards and regulations for safety testing primarily focus on the function of new products. Research is conducted in order to understand the underlying degradation mechanisms with the scope to avoid severe reoccurring long-term defects in the future.
However, this work does not address the current need to assess the daily found backsheet issues in the field.
As of today, approximately 60 GWp PV systems are currently connected to the grid in Germany; a large proportion of them are now more than five years old and increasingly exhibit anomalies of the backsheet such as chalking, decoloration and cracking. Several of the observed anomalies are merely cosmetic at this stage, while others pose an inherent electrical safety risk as electrical live parts at high DC potentials are exposed. In addition to electrical safety, a defective backsheet can also result in significant yield loss due to the shutdown of system components.
However, there are no existing recommendations for action in the form of standardized rules and criteria with regard to faulty backsheets. The ANOMALOUS project addresses precisely this shortcoming.
The investigations carried out within the scope of the ANOMALOUS project serve to close the existing normative gap in the evaluation of backsheets in the field and establish uniform criteria for the evaluation of abnormalities.
The project work focuses on the development of a VDE application rule and a standardization application that define criteria for evaluating older PV systems while providing recommendations for action for assessors and maintenance companies. The resulting catalog of abnormalities will also provide more legal certainty in the individual steps of the value chain. In addition, research findings will be made available to the PV market in order to significantly increase the lifetime of PV modules and thus contribute to reducing the carbon footprint required for the production of new modules.
The partners with whom we collaborate on this project