Novel Mechano-Chemical Approach to Achieve Rapid Delamination of Glass from Solar Panels

With growing global cumulative photovoltaics (PV) installation, end-of-life (EoL) PV panels are expected to grow as well, with reports predicting this number to reach 78 million tonnes by 2050. This huge amount of PV waste does not only present a looming environmental challenge but also an opportunity to recover valuable materials embedded in the panels.<br/><br/>Different generations of PV technologies (1st Gen - Crystalline silicon (c-Si), 2nd Gen - Thin film (CIGS, CdTe) and 3rd Gen - Emerging PV (Perovskite, Bifacial)) have presence in the market currently. Out of all of these technologies, c-Si modules have the largest market share. Irrespective of their differences, the device stack for these PV technologies follows a sandwich structure, with the active layer (comprising metals and semiconductors) layered between polymeric encapsulants and glass. These insulating layers ensure a longer lifetime for panels in the field.<br/><br/>However, the same device structure creates challenges to recover valuable materials efficiently. Different approaches have been developed to separate the layers of solar panels. Thermal approaches burn the polymeric layers. However, they can produce toxic gases and affect the purity of active layer materials. Mechanical approaches crush the panel and sieve into different fractions. However, that often leads to undesired cross-contamination and affects the output yield and quality. Chemical approaches can give high output yield and purity and rely on dissolution of the polymeric encapsulant to separate the layers. However, they can take a long time (up to 7 days) making it less attractive.<br/><br/>Herein, we report a novel mechano-chemical approach that relies on weakening of bonds between glass layer and encapsulant layer through use of a green solvent. Cleaving of glass from the solar panels is achieved through mechanical processing. This process achieves rapid delamination of glass from solar panels (&lt;4 hours) and high purity (&gt;98%) glass cullet, while providing access to the active layer of the panel. The process has been demonstrated for c-Si panels and can be translated to different generations of solar panels.