Using femtosecond lasers to kind glass-to-glass welds for photo voltaic modules would make the panels simpler to recycle, in line with a proof-of-concept examine performed by researchers on the U.S. Division of Vitality’s Nationwide Renewable Vitality Laboratory (NREL).
The welds would remove the necessity for plastic polymer sheets that at the moment are laminated into photo voltaic modules however make recycling harder. On the finish of their helpful lifespan, the modules made with the laser welds could be shattered. The glass and steel wires working by the photo voltaic cells could be simply recycled and the silicon could be reused.
“Most recyclers will verify that the polymers are the primary situation by way of inhibiting the method of recycling,” mentioned David Younger, senior scientist and group supervisor for the Excessive-Effectivity Crystalline Photovoltaics group within the Chemistry and Nanoscience division at NREL. Younger is lead writer of a brand new paper outlining using laser welds for photo voltaic modules. The paper, “In the direction of Polymer-Free, Femto-Second Laser-Welded Glass/Glass Photo voltaic Modules,” seems within the IEEE Journal of Photovoltaics.
Written with NREL colleagues Tim Silverman, Nicholas Irvin, and Nick Bosco, the paper additionally counts as its coauthors two staff of Trumpf Inc., the California firm that made the femtosecond laser concerned. A femtosecond laser makes use of a brief pulse of infrared gentle that melts the glass collectively to kind a robust, airtight seal.
The glass weld can be utilized on any kind of photo voltaic expertise — silicon, perovskites, cadmium telluride — as a result of the warmth of the weld is confined to a couple millimeters from the laser focus.
Photo voltaic modules are manufactured from semiconductors designed to seize a selected portion of the photo voltaic spectrum, harnessing daylight to create electrical energy. Sometimes, the semiconductors are sandwiched between two sheets of glass laminated along with polymer sheets.
NREL’s analysis confirmed that femtosecond laser, glass/glass welds are primarily as sturdy because the glass itself.
“So long as the glass does not break, the weld shouldn’t be going to interrupt,” he mentioned. “Nonetheless, not having the polymers between the sheets of glass requires welded modules to be a lot stiffer. Our paper confirmed that with correct mounting and a modification to the embossed options of the rolled glass, a welded module could be made stiff sufficient to cross static load testing.”
NREL’s analysis is the primary to make use of a femtosecond laser to kind glass/glass welds to be used in a module. A unique kind of edge sealing utilizing nanosecond lasers and a glass frit filler was tried up to now, however the welds proved too brittle to be used in out of doors module designs. The femtosecond laser welds supply superior energy with airtight sealing at a compelling price.
Younger mentioned the analysis is “undoubtedly excessive danger, excessive reward,” however factors to a route for additional analysis to increase the lifetime of photo voltaic modules to past 50 years and to permit simpler recycling.
