This Phase II program will demonstrate an innovative, module-level encapsulation technology that will lower the cost by at least 50% and enhance the performance of space-grade solar arrays. Conventional solar cells for space use specialized coverglass that provides essential environmental protection from high-energy particle and ultraviolet solar radiation but is expensive to apply and has high fragility. Next-generation coverglass replacement materials have been explored by several groups over the past decade. Pseudomorphic glass (PMG) uses glass microbeads embeded in a silicone matrix that can be formed into sheets or sprayed on interconnected modules. Pure silicone sheets using space-grade DC 93-500 have also been investigated for module-level protection. Both approaches have the additional benefit of high flexibility that is synergistic with thin-film, inverted metamorphic multi-junction (IMM) solar cells manufactured by MicroLink Devices, enabling a pathway to truly flexible solar modules.
The central innovation in this proposal is to introduce a novel, prismatic texturing method that will improve the performance and manufacturability of silicone-based encapsulations including PMG. Texturing of glass encapsulants has previously been explored for enhancing high-angle light capture for terrestrial solar arrays, but prismatic structuring of space coverglass has not been widely investigated. Polymer materials are much more readily formed into prismatic shapes, which presents a new opportunity to introduce this important technique. During the Phase I program MicroLink demonstrated 4% higher output power as well as enhanced high-angle capture using low-cost prismatic silicone and robust UV rejection (UVR) coatings. This was used to fabricate the first truly flexible, space-grade module with multi-junction solar cells. Deployable, retractable arrays such as the Lunar VSAT would be an excellent application for the new module technology.