By Arrelaine A. Dameron, Postdoctoral Researcher, National Center for Photovoltaics, NREL; Matthew O. Reese, Postdoctoral Researcher, National Center for Photovoltaics, NREL; Thomas J. Moricone, Research Technician, PV Module Reliability Group, NREL; Michael Kempe, Scientist, PV Module Reliability Group, NREL
Outside of the challenges of fabricating state-of-the-art photovoltaic devices, further care must be taken to package them such that they can withstand environmental conditions for an accepted lifetime of 20-plus years. Moisture ingress is a big adversary to hermetic packaging. The diffusion of water through barriers and edge seals can be minimized by careful choice of materials and package/barrier architecture. However, at present, there exist no solutions for extremely water-sensitive materials for flexible applications. Presented in the following is a review of the physics of permeation, the means of measuring permeation, current architectural strategies for semi-hermetic packages, and a brief evaluation of some common encapsulant materials.