Résumé

Q1 Q1 as a clean energy source since the 1970s. To date, their efficiency has been improving continuously thanks to advances in architecture, materials, and processing 1 . To preserve their high performance against environmental stresses such as mechanical load, corrosive chemicals, temperature, and high-energy light, they rely on the PV module structure to minimize the induced degradation mechanisms. PV modules are generally made of front and back protection layers that surround two polymer sheets that encapsulate PV cells. The front layer is usually made of glass, and the back layer can be glass or a multilayer polymer (backsheet). The polymer sheets inside the module are called encapsulants. They are key players in light transmission, electrical insulation, mechanical stress absorption, heat removal, chemical barrier protection and PV module integrity. To maintain such properties throughout a module lifetime that is now ~30 years 2 , encapsulants must cope with the most stringent terrestrial conditions that lead to highly detrimental chemical reactions such as hydrolysis or photooxidation. Concerning terrestrial applications, most photodegradation reactions of encapsulants involve UV light between 300 and 400 nm 3 . Consequently, accelerated photoaging tests are usually run under various UV sources, including xenon arcs or fluorescent tubes, which simulate this part of the solar spectrum 4 .