France’s CEA developing tech to recover silicon, silver from end-of-life PV panels

The French Alternative Energies and Atomic Energy Commission (CEA) has developed a recycling process for end-of-life PV modules, recovering silicon and silver, using supercritical CO2. Virginie Basini, head of CEA’s sustainable technologies department, discussed the technique with pv magazine France.

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From pv magazine France

The European aim to establish a PV value chain faces the sector's substantial raw material requirements. Given the energy transition context, recycling valuable materials is of strategic importance. With this objective, CEA has harnessed its technical expertise to create an innovative process for recycling silver and silicon at the end of their life cycle.

“The CEA has been deploying R&D for more than 60 years in a circular economy context, with the nuclear fuel cycle which is part of this logic of circularity,” Virginie Basini, head of CEA's sustainable technologies department, told pv magazine France.

The agency developed the innovative recycling process for silver and silicon, drawing from techniques initially designed for nuclear power. This method involves the use of a supercritical carbon dioxide (CO2) delamination process to separate critical elements, such as silver and copper, from a key raw material like silicon.

The process employs supercritical CO2, which represents a state of carbon dioxide with properties intermediate between a liquid and a gas. It is achieved when CO2 surpasses its critical point at 31°C and 73.8 bars of pressure. In this state, CO2 infiltrates solids, particularly the polymer encapsulating the solar cells. When researchers conduct depressurization, the CO2 within the encapsulating polymer transforms back into a gaseous state, causing the polymer to expand and foam. This deformation results in the separation of different layers in the PV module, enabling their individual recovery.

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Silver represents more than 30% of a panel's value.

“The whole challenge of recycling is to guarantee maximum purity of this high-value material in order to allow its reuse,” Basini said. “This is also the case for silicon, the majority of which recovered could be directed towards the high purity silicon sectors used in microelectronics or photovoltaics. The glass, which remains intact after delamination, can also be recycled in the flat glass sector.”

While there isn't an established channel for repurposing panels, a significant growth in such utilization is anticipated in the near future. In the Auvergne Rhône-Alpes region, an emerging industrial sector is being shaped by Solreed, a company established in 2023 as a CEA spinoff. This startup is set to forge partnerships among private, public, and ESS entities to drive the development of this novel sector.

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