Técnicas Reunidas promotes the circular economy in the photovoltaic sector through the ReSil2Volt project

• The project addresses one of the key technological challenges of the energy transition: recovering and transforming strategic materials from endoflife solar panels to reintroduce them into the manufacturing of new photovoltaic cells. 
• Técnicas Reunidas leads ReSil2Volt under the RENOCICLA Programme, funded by the Institute for Energy Diversification and Saving (IDAE) and the Ministry for the Ecological Transition and the Demographic Challenge (MITECO).

The project focuses on the valorization of silicon powder (“grey mass”), a complex fraction generated during the primary treatment of photovoltaic panels. This material contains critical elements such as silicon, silver, aluminium, tin, copper, and lead.

Its heterogeneous composition makes its processing technically challenging. As a result, it is currently one of the main bottlenecks preventing full circularity in the photovoltaic sector. 

ReSil2Volt develops an integrated solution to recover these strategic materials and return them to the value chain as solargrade silicon and silver, suitable for use in wafers and conductive pastes.

At the core of the project lies the ReSil2Volt technology, a modular hydrometallurgical process, free from hazardous waste, designed to operate with high efficiency and adapt to variations in feedstock composition. 

This technology enables the recovery of metallurgicalgrade silicon (MGSi) and silver chloride (AgCl) with efficiencies above 95%. The process also generates valuable byproducts such as AlCl₃ and a metal cement. 

To enable the reintegration of these recovered materials into the photovoltaic sector, the project will investigate advanced metallurgical purification pathways —including slag refining— to upgrade the recovered metallurgicalgrade silicon into solargrade silicon (SoGSi) by removing critical impurities (B, P, Fe, Al, Ti) and reaching purities around 6N (99.9999 %). 

In parallel, the recovered AgCl will undergo controlled reduction processes to obtain 4N metallic silver (99.99 %), suitable for manufacturing photovoltaic conductive paste. 

Técnicas Reunidas, the project’s lead entity, heads the design, research, and validation of all key process stages—from continuous hydrometallurgical treatment to metallurgical purification and the production of photovoltaicgrade materials. Leveraging its pilotscale infrastructure, extensive experience in hydrometallurgy, and proprietary technologies such as ZINCEX®, RARETECH®, and PHOS4LIFE®, the company strengthens its position as a benchmark in circulareconomy solutions for critical raw materials. 

The project, with a duration of 30 months and a total budget of €1,830,394, will be fully executed at the Technology Centre of Técnicas Reunidas, where the technology will be validated to generate essential knowledge for future scaleup and integration into industrial photovoltaicrecycling ecosystems.

In short, ReSil2Volt will:

• Reintroduce recycled silicon and silver as highquality secondary raw materials.
• Reduce dependence on virgin raw materials and the environmental footprint associated with their extraction.
• Deliver a modular, scalable, and hazardfree technological solution.
• Lay the foundations for a circular industrial model in the photovoltaic sector. 

The project is fully aligned with the objectives of the Strategic Project for Economic Recovery and Transformation (PERTE) for the Circular Economy, the Recovery, Transformation and Resilience Plan, and the requirements of the European Critical Raw Materials Act.