According to David Young, the lead author of the article, recyclers often cite polymers as a significant obstacle in the recycling process. To address this issue, scientists conducted an experiment using a femtosecond laser, which uses short pulses of infrared light to melt glass together and create a strong, hermetic seal. The glass weld produced by the laser can be applied to any type of solar technology, including silicon, perovskites, and cadmium telluride, as the heat is concentrated near the laser focus.
Solar modules are typically made of semiconductors sandwiched between two sheets of glass laminated with polymer sheets. However, NREL’s research indicated that glass/glass welds are just as strong as the glass itself. This means that if the glass does not break, the weld will remain intact. Although eliminating the polymers between the glass sheets makes the welded modules stiffer, proper mounting and modifications to the glass features can ensure that these modules pass static load testing.
The femtosecond laser welding technique is a groundbreaking approach to creating glass/glass welds for solar modules. Previous attempts using nanosecond lasers and glass frit fillers resulted in brittle welds unsuitable for outdoor module designs. In contrast, the femtosecond laser welds offer superior strength and hermetic sealing at a reasonable cost, opening up new possibilities for the longevity and recyclability of solar modules.
David Young believes that this study points towards a promising direction for future research in extending the lifespan of solar modules beyond 50 years and making recycling easier.