Proof of concept study shows path to easier recycling of solar modules

The usage of femtosecond lasers to type glass-to-glass welds for photo voltaic modules would make the panels simpler to recycle, in response to 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 are actually 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 solar cells could be simply recycled and the silicon could be reused.

“Most recyclers will confirm that the polymers are the main issue in terms of inhibiting the process 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 the usage of laser welds for photo voltaic modules.

The paper“Towards Polymer-Free, Femto-Second Laser-Welded Glass/Glass Solar 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 co-authors 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 mild that melts the glass collectively to type a powerful, 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 fabricated from semiconductors designed to seize a particular 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.

“As long as the glass doesn’t break, the weld is not going to break,” he mentioned. “However, not having the polymers between the sheets of glass requires welded modules to be much stiffer. Our paper showed that with proper mounting and a modification to the embossed features of the rolled glass, a welded module can be made stiff enough to pass static load testing.”

NREL’s analysis is the primary to make use of a femtosecond laser to type glass/glass welds to be used in a module. A distinct kind of edge sealing utilizing nanosecond lasers and a glass frit filler was tried previously, 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 “definitely high risk, high reward,” however factors to a course for additional analysis to increase the lifetime of solar modules to past 50 years and to permit simpler recycling.