Balancing and evaluation of the water jet cutting process for the composite separation of photovoltaic modules

The increasing number of photovoltaic modules (PV modules) that have reached the end of their life requires effective recycling solutions. To fully recycle all layers (backsheet, solar cells, glass) of PV modules, an effective separation method is required. In this work, the use of the waterjet cutting process to separate the PV components backsheet, solar cells, and glass is investigated and a mass balance was drawn up. A total of five PV modules from three different production types were subjected to the waterjet cutting process. The pressure and feed rate of the waterjet were adjusted so that only one layer was removed at a time. It is essential to carefully control the water jet parameters during backsheet removal to prevent damage to the underlying solar cells. Compared to the removal of the backsheet, higher pressure and lower feed rates were used to remove the solar cells so that the cells could be removed without leaving any residue. After each layer had been removed, the separated components (backsheet, solar cells, and glass) were collected and samples were taken. Additionally, water samples were taken throughout the entire process to estimate material loss during the procedure. A mass balance was created using the collected data to determine the average masses of the extracted raw materials and to estimate the mass loss. The values were also compared with other literature values. The tests showed that the quality of the separation of the components depends on parameters related to the origin (age, weather, production method, etc.) of the modules. These parameters were unknown for the PV modules used in this experiment. However, the process itself has proven effective, and the separation of the backsheet, solar cells, and glass is possible. An average mass loss of 1.2 kg was determined. Possible explanations for this mass loss include varying moisture levels in the samples; on the one hand, the modules were stored outdoors before the experiment and were therefore damp from rain. However, the mass loss may also have been partially caused by the process itself. Since high pressures are present during waterjet cutting, material is also thrown through the air. This makes it challenging to maintain a closed system for the experiments. Mass loss via wastewater is minimal. By cleaning and recirculating the water, valuable raw materials can be recovered.