The use of femtosecond lasers to form glass-to-glass welds for solar modules could revolutionize the industry by making the panels easier to recycle. Currently, solar modules are laminated with polymer sheets that complicate the recycling process. By eliminating the need for these polymer sheets, the modules can be easily shattered at the end of their useful lifespan, allowing for the glass and metal wires within the modules to be recycled and the silicon to be reused. This new method was developed by researchers at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) and is outlined in a new paper published in the IEEE Journal of Photovoltaics.
The femtosecond laser welds are achieved through a short pulse of infrared light that melts the glass together, creating a strong, hermetic seal. This technology can be used with any type of solar technology, such as silicon, perovskites, or cadmium telluride, as the heat from the weld is only focused on a few millimeters around the laser point. The research conducted by NREL demonstrated that the glass/glass welds created with the femtosecond laser are as strong as the glass itself. This new method offers a compelling alternative to the traditional polymer lamination process, as it provides superior strength and hermetic sealing at a comparable cost.
One of the challenges faced in developing the femtosecond laser welds was ensuring that the welded modules were stiff enough to pass static load testing. However, the research showed that with proper mounting and modifications to the embossed features of the rolled glass, the welded modules can meet the required stiffness standards. This groundbreaking research is the first to use a femtosecond laser to form glass/glass welds for solar modules. Previous attempts to use nanosecond lasers and glass frit fillers for edge sealing proved to be too brittle for outdoor module designs, highlighting the superior strength and reliability of the femtosecond laser welds.
While the research is considered high risk, the potential rewards are significant in terms of extending the lifespan of solar modules to beyond 50 years and facilitating easier recycling. By removing the polymers from the solar modules, the recycling process can be streamlined, making it more efficient and environmentally friendly. This innovation could pave the way for a more sustainable solar industry, reducing waste and maximizing the reuse of valuable materials. The collaboration between NREL and Trumpf Inc., the company that provided the femtosecond laser, underscores the importance of partnerships in advancing renewable energy technologies.
