Backsheets for PV Modules with a Service Life of at least 40 Years

The quality and workmanship of the encapsulation and backsheet films play a significant role in the reliability of a solar module. Only when the quality, workmanship, and compatibility of the films are right can the interconnected solar cells be protected from environmental influences and the module remain operational for decades. The Fraunhofer Center for Silicon Photovoltaics CSP is working with partners to investigate innovative encapsulation and backsheet films for PV modules that are expected to have a service life of at least 40 years.

The polymer encapsulation and backsheet films in solar modules contribute significantly to their efficiency, longevity, and resistance. The films protect the interconnected solar cells from environmental influences such as rain and moisture, oxidation, and UV radiation, as well as from mechanical stress and chemical contamination, and must meet a number of requirements.

New developments in the field of solar module films are focusing on the longevity of the modules, their resistance, and cost optimization. This is where the newly launched “Folie40” project comes in. The consortium of film and module manufacturers and research institutions aims to jointly develop innovative encapsulation and backsheet films for PV modules with a service life of at least 40 years. Currently, photovoltaic module manufacturers offer a performance guarantee of 25 years on 80 percent of the initial output.

Fraunhofer CSP is contributing its expertise in polymer analysis and polymer evaluation to the project and is working on questions that will help to understand material changes under realistic operating conditions. To this end, the scientists are systematically conducting weathering tests with varying stress parameters, which are correlated with the results of outdoor weathering. In addition, they want to create a benchmark materials database for identifying the relevant material properties for increased service life. This will allow conclusions to be drawn about the relationship between film material formulation, material combinations, material aging, and environmental conditions, enabling service life predictions specific to the application site.