This Phase I 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. In this Phase I program MicroLink will demonstrate that prismatic structures not only increase the high-angle collection efficiency of space solar cells by up to 30%, but also reduce the operating temperature by as much as 3 degrees. Equally important, the surface texturing is expected to substantially simplify the design and robustness of essential UV protective coating layers deposited over the encapsulation.