Simple pretreatment processes for successful reclamation and remanufacturing of crystalline silicon solar cells

This study presents an effective method for recovering unbroken solar cells from photovoltaic (PV) modules. The combustion process is effective at removing ethylene vinyl acetate (EVA) in PV modules. However, the solar cell tends to break during the combustion process. We verify that the breakage mechanisms of the solar cell in the module are related to the thermal changes of EVA during the heat treatment process, that is, generated gases form bubbles behind the glass, and the thermal deformation of the rear EVA applies stress to the solar cell. This study investigates the simple pretreatments of glass cracking and EVA patterning to prevent the breakage behavior. An unbroken solar cell was successfully recovered from the module after complete EVA removal using the combustion process. The recovered solar cell was immersed in a mixed acid solution of HNO3 and HF to reclaim the crystalline silicon wafer, which subsequently underwent the solar cell manufacturing process. The PV performances of the solar cells based on the reclaimed wafer and a commercial wafer were evaluated and compared. The PV performance of the solar cell manufactured from the reclaimed wafer was measured at 18.5%, whereas that from the commercial wafer-based solar cell was measured at 18.7%. Consequently, the considered pretreatment processes yielded solar cells acceptable for use in the PV industry.