Encapsulation is a key step in the photovoltaic module manufacturing process. Cells are connected in parallel or series, and then placed between two layers of a transparent polymer to ensure the integrity of the module and protect it from exposure to the elements. "The polymer starts out soft. It then undergoes a process called reticulation, which hardens it," said a researcher. "After the process, the reticulation rate must be checked to ensure the quality of the assembly."
Liten and Arkema worked together to develop an idea that originated at Arkema. The resulting method leverages DSC (differential scanning calorimetry) observation of the encapsulant's crystallization peak. "The technique takes just a few minutes and, unlike the traditional solvent-extraction method, does not require any toxic substances." The process, called Melt Freeze, was proven effective on several types of EVA (ethylene vinyl acetate) and is currently being tested on other materials.
The method also earned international recognition when it was included in the brand new standard for measuring materials used in photovoltaic modules, IEC 62788-1-6: 2017. An additional method using Raman spectrometry is also being developed at the lab as part of a PhD research project.
CEA is a French government-funded technological research organisation in four main areas: low-carbon energies, defense and security, information technologies and health technologies. A prominent player in the European Research Area, it is involved in setting up collaborative projects with many partners around the world.