Thin glass under stress: researching and predicting glass breakage

In photovoltaic technology, not only higher efficiencies but also reduced material consumption, sustainable materials, as well as the reliability and durability of solar modules are becoming increasingly important. Glass-glass modules, in which solar cells are protected between two glass panes, offer significant potential. By using thinner glass sheets (less than 2.2 mm thick), material usage and weight can be reduced. At the same time, however, ensuring sufficient mechanical stability becomes more challenging. This is where the "SmaShGlas" project of the Fraunhofer Center for Silicon Photovoltaics CSP in Halle (Saale), Germany, comes in. The project investigates how different types of impacts, such as hailstones, stones, or tools, affect the stability of PV modules equipped with ultra-thin glass panes. The goal is to reliably predict glass breakage.

For thin, tempered glass and the double-glass laminates manufactured from it, suitable assessment methods are currently lacking to reliably evaluate their behavior under realistic operating conditions. Existing hail tests cover only a subset of possible mechanical loads. As a result, comparing different module designs or clearly identifying the causes of glass breakage remains challenging. In addition, mounting systems, supporting structures, and module configurations should also be taken into account. This creates technical and economic risks for manufacturers, planners, operators, and maintenance companies.

"In the project, we therefore combine computer simulations with practical testing. We investigate both large-area loads acting on the entire module and short-term, localized impacts such as those caused by hail. Since installation conditions have a significant influence on module stability, the module and its supporting structure are considered as an integrated system," explains Matthias Pander, Project Manager at Fraunhofer CSP. In addition, the project examines how even the smallest material or surface defects can initiate and propagate cracks, ultimately leading to glass breakage.

The simulations are validated and continuously refined using real-world load tests. This approach aims to create optimized models that enable the load limits of PV modules to be determined more quickly, more reliably, and with fewer extensive validation test campaigns. It will also facilitate root-cause analysis of glass failures that have already occurred. Based on the findings, practical testing methods, threshold values, and design recommendations for thin-glass PV modules will be developed. Manufacturers and system designers will thereby gain a stronger foundation for creating safe and comparable module concepts. At the same time, the project results will support the development of lighter, more reliable, and more hail-resistant PV modules, particularly for applications in vehicles and installations with limited load-bearing reserves.

In the long term, the findings can also be transferred to other thin-glass applications, such as building-integrated photovoltaic façades or vehicle roof systems. Furthermore, they are expected to open up new possibilities for innovative, ultra-lightweight PV designs. By reducing breakage rates, extending service lifetimes, and lowering material consumption, the project can contribute to making photovoltaics more robust, sustainable, and cost-effective.

(October 12, 2026)