The ReSil2Volt project addresses the advanced valorization of silicon powder (“grey mass”) generated from the recycling of end oflife photovoltaic panels through an innovative hydrometallurgical route that enables the recovery and purification of silicon and silver with sufficient purity to be reintroduced into the production of new solar cells.
The proposal focuses specifically on the recovery and purification stages, while the integration into photovoltaic cells—already industrially mature—lies outside the project scope. In this way, the project contributes to closing the loop of critical materials and fostering circularity with in the solar sector.
The project specifically focuses on the valorization of silicon powder (“grey mass”), a complex fraction generated after the primary treatment of solar panels, which contains critical materials such as silicon, silver, aluminum, tin, copper, and lead.
Utilizing this fraction represents a significant technological challenge, as its heterogeneous composition currently constitutes one of the main bottlenecks to achieving a truly circular economy in the photovoltaic sector.
ReSil2Volt proposes a comprehensive solution to recover these strategic materials and reintegrate them into the value chain in the form of photovoltaic grade silicon and silver, suitable for use in wafers and conductive pastes.
The core of the project is the ReSil2Volt technology, a modular hydrometallurgical process, free of hazardous waste, designed to operate with high efficiency and to adapt to variations in raw material composition. This technology enables the recovery of metallurgical grade silicon (MGSi) and silver chloride (AgCl) with recovery efficiencies above 95%. Additionally, the process also recovers valuable byproducts such as aluminum trichloride (AlCl₃) and a metal cement.
To enable the reintegration of recovered raw materials into the photovoltaic sector, the project will investigate advanced metallurgical purification routes, such as slag refining, to convert recovered metallurgical grade silicon into solar grade silicon (SoGSi) by removing critical impurities (B, P, Fe, Al, Ti) and achieving purities on the order of 6N (99.9999%).
In parallel, the recovered AgCl will undergo controlled reduction processes to produce metallic silver with 4N purity (99.99%), suitable for the manufacture of photovoltaic conductive pastes.
