Degradation kinetics of polymer encapsulation materials for use in photovoltaic modules

• Applicant: Professor Dr. Ralph Gottschalg
• Subject Area: Polymeric and Biogenic Materials and Derived Composites ; Electrical Energy Systems, Power Management, Power Electronics, Electrical Machines and Drives
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 538707333

The photovoltaic industry has experienced immense growth in recent years. Consequently, in terms of energy supply security and the economical use of resources, it is essential to be able to predict the lifetime of solar modules as accurate as possible. At the level of the solar module, lifetime and performance simulations have so far been carried out primarily on a purely empirical basis. Various degradation rates are calculated from macroscopic process variables without considering the deeper physical and chemical effects. At the material level, only the behavior of individual components is usually evaluated and the interaction with other layers is not taken into account. Due to this initial situation, degradation rates of different material combinations are difficult to predict. It is known that many degradation effects of solar modules are due to the aging behavior of the polymeric components. The proposed project aims to relate the macroscopic degradation rate of solar modules (i.e., power loss) to the underlying degradation effects of the polymeric constituents. The specific objectives for the project are as follows: i. Develop a novel UV aging system to analyze spectral influences on polymer degradation with variable temperatures. ii. Determine the influence of the interaction of different solar module components and polymer layer additives on the aging behavior of the encapsulation polymers and ultimately on the degradation of the overall module. iii. Modeling of the material changes of the encapsulation polymers as a function of spectral influences and correlation with module degradation. The chemical aging of the polymer layers and the interaction of the individual components are analyzed significantly with the aid of the large-scale instrument (triple Raman spectrometer with single photon counting). Through diverse preliminary work, a solid basis has already been created to achieve the goals defined in the project. For example, a method was developed to quantify the additives contained in polymer films and consequently to investigate their degradation behavior in dependence of various stressors. Furthermore, it could be shown that the aging behavior of encapsulation polymers at different locations in the solar module strongly differs from each other and from the aging behavior of a single polymer layer. Consequently, a holistic view of the module is imperative. The influence of the illumination spectrum on the degradation behavior of polymer layers was also investigated. It was shown that spectral photon distribution has a greater influence on degradation behavior than cumulative radiation intensity.

• DFG Programme: Research Grants