Thermal and optical properties of edge sealed photovoltaic modules

Abstract

As the global demand for clean energy accelerates, photovoltaic (PV) technologies must evolve not only to improve performance and reduce cost, but also to address sustainability and end-of-life considerations. Traditional PV modules rely heavily on polymeric encapsulants such as Ethyl Vinyl Acetate (EVA), which contribute to long-term degradation mechanisms including acetic acid formation, potential-induced degradation (PID), and recycling challenges. This study presents the design, fabrication, and evaluation of an encapsulant-free Edge Sealed Module (ESM) architecture developed at Colorado State University. The ESM eliminates vacuum lamination and conventional encapsulants by enclosing photovoltaic cells within an air-filled, edge-sealed glass-glass structure, enhanced with nano-textured surfaces for optical and thermal performance. The optical performance of ESMs was evaluated by comparing short-circuit current (ISC) to traditional modules under outdoor conditions using a custom-built In-Situ Data Logger. Results indicate that textured ESMs match the optical output of traditional modules within experimental error. Thermal performance was assessed through open-circuit voltage (VOC) measurements, showing that ESMs exhibit similar or improved thermal behavior compared to traditional counterparts, particularly when enhanced with surface textures that promote internal convective cooling. Ultraviolet (UV) stability of PMMA-based nano-textures was also investigated. While encapsulated samples showed minimal degradation, un-encapsulated textures experienced significant transmission loss and delamination, confirming the need for robust edge sealing to ensure durability. In addition to performance, the ESM design offers a simplified manufacturing process with significant reductions in cycle time, factory floor space, and material costs. Mechanical testing shows increased structural strength compared to laminated modules. These findings suggest that ESMs provide a viable path forward for next-generation PV module design—balancing efficiency, reliability, and sustainability while supporting the Department of Energy's 50-year module lifetime goal.