Our ‘solar reliability’ area focuses primarily on studying the thermomechanical reliability of photovoltaic module components, from frontside optics to encapsulation and backsheet structures. We utilize a fracture mechanics based approach to understand the fundamental degradation mechanisms of module materials and interfaces. This includes significant participation from national laboratories and industry collaborators, who provide us with the most modern and relevant solar technologies.
Recently, a reliable and repeatable method of characterizing adhesive properties of module interfaces has not existed. However, through collaboration with the Bay Area Photovoltaic Consortium (BAPVC) and the National Renewable Energy Laboratory (NREL), we developed simple metrologies that, for the first time ever, provide direct, quantitative measurements of adhesion in encapsulation and backsheet structures. These techniques have been used to evaluate adhesion in 30-year-old field modules and, ultimately, provide a framework for one-to-one comparisons of modules that have operated in different terrestrial environments. Advanced characterization techniques are frequently utilized, such as WAXS/SAXS with our collaborators at SLAC, to complement and elucidate the mechanical adhesion measurements.
Recent work on modeling the degradation of solar encapsulation has been carried out as part of the Department of Energy’s SunShot Initiative in collaboration with NREL (published cover art shown above). Fundamentally modeling the kinetics and mechanics of solar encapsulant degradation is critical to providing predictive capabilities as solar power generation becomes more widespread globally. Delamination of the encapsulant is preceded by a breakdown of the mechanical integrity of the encapsulant layer. Over time, this degradation diminishes the critical adhesion energy required to induce delamination to levels below empirically determined threshold values, making delamination much more likely through normal usage. Our work in determining the fundamental mechanisms and kinetics that drive this loss in adhesion energy provides the solar community with an essential understanding of the reliability considerations that are vital to expanding the usage of solar modules into additional terrestrial environments and integrating potential new materials as solar encapsulants. As industrial partners seek to avoid premature failures and to increase the guaranteed lifetimes of solar modules, understanding how a critical component of these solar modules degrades and ultimately leads to delamination is elemental.
While so much time is allocated to discussing efficiencies of solar modules, the actual mechanical durability and reliability of the solar modules is often ignored and underappreciated. From optics to encapsulation to the cells themselves, we have developed and employed testing methods to evaluate the reliability of these materials and furthermore, continue to expand on and develop the knowledge and understanding crucial to advancing the goals of the solar community and ensuring future success.
Current Research Projects
- Adhesion and Reliability of Photovoltaic Materials
- Advanced Characterization of Encapsulant Degradation
Past Research Projects
- Tearing of Backsheet Structures in Photovoltaic Modules
- Thermomechanical Degradation of Multijunction Photovoltaics
- Developing New Testing Metrologies for Brittle Films and Fragile Substrates
- Reliability and Degradation of Optics and Encapsulants and Concentrated Photovoltaics
- Increasing Adhesion Energy of Organic/Inorganic Interface Through Nanoscale Structures
- Adhesive Bonded Composite Joints
- Full-field Deformation Mapping
- Reliability and Enviornmental Degradation of Polymer-Oxide Interfaces