A promising method for the liberation and separation of solar cells from damaged crystalline silicon photovoltaic modules

Abstract

Reasonable and efficient recycling of waste crystalline silicon (c-Si) photovoltaic (PV) modules benefits environmental protection and resource conservation. The liberation and separation of solar cells in modules is the key to achieving effective recycling. The recovery of intact waste modules has been studied by some scholars, but few have specifically examined damaged modules. This study focused on modules that have been broken during transportation, installation, use, or disassembly. Two liberation methods, mechanical crushing and pyrolysis were compared from the perspectives of particle size distribution and morphological characteristics of products. In addition, for separating glass particles and solar cells of coarse fraction, an environmentally-friendly technology of gas-solid fluidized bed was introduced based on their shape and density difference. The effects of airflow velocity and fluidizing time on separation efficiency were investigated for different size fractions. Results showed that pyrolysis was a more suitable liberationliberation method for damaged modules. Higher liberation efficiency could be obtained by pyrolysis, and over-crushing of glass particles and solar cells could be avoided. The optimum pyrolysis conditions were found to be at 500 °C with a holding time of 30 min. The recovery and concentration of solar cells in the >4 mm size fraction were 91.09% and 84.4%, respectively, under the following conditions: 85 m3/h airflow velocity; 90s fluidizing time. For the 2–4 mm size fraction, the recovery and concentration were 82.29% and 80.52% under airflow velocity of 75 m3/h, fluidizing time of 90s. This research presents an alternative process for recovering damaged c-Si PV modules.