Photovoltaic (PV) technology configures as a competitive technological alternative to convert solar radiation into electricity, and it is expected to provide a fundamental contribution to the transition from traditional fossil fuels to economies based on renewable energy. This technology has been applied since the 1980s, with the first significant installation dating back to the early 1990s. Si-crystalline (mono and poly) panels represent the most consolidated PV technology and have dominated the PV market over the past decades, with 92% of the PV market share. In order to reduce the panel production costs, alternative PV technologies have been developed, including between the panels a thin film of Copper Indium Gallium Selenide (CIGS). PV technologies imply the use of precious and rare metals such as Silver in Si panels and Indium and Gallium in CIGS panels. Available data from the literature reported a range of concentrations in PV panels from 20 to 600 mg/kg for Ag, 80–200 mg/kg of In and 25–310 mg/kg for Ga. Variability of metal concentrations depends on the time of production and specific manufacturing technologies aiming at reduction of production costs: for example, Ag concentration in PV panels is expected to be reduced from 0.14%–0.2% in 2003 to 0.07%–0.16% in 2023. The average lifetime of a PV panel is estimated to be around 25 years irrespective of the considered technology. Since the electric power share from PV installations became relevant starting from the end of nineties, a dramatic increase in the annual flux of end-of-life PV panels can be expected around 2025. Motivated by this forecast analysis, several recycling processes have been proposed to recycle PV panels. The main target of the proposed processes is to meet the material recovery targets set by the relevant regulation (EU, 2012), ensuring, at the same time, economic and environmental sustainability. Many works on PV panel recycling were focused on the treatment of Si-panels and cadmium telluride (CdTe) panels. Treatments of Si modules mostly remove the Al frame and the junction box mechanically or manually, followed by the use of high temperatures in order to modify the characteristics of the solar modules and decompose ethylene-vinyl acetate (EVA), which allows for the subsequent mechanical separation of clean glass and Silicon solar cells. The obtained separated cells can be then chemically treated with acids to dissolve metals, and further purification steps can be performed. Another approach is EVA dissolution by the contact with organic solvents. Cadmium and Tellurium are the main targets of CdTe panel recycling, which typically comprises the acid treatment of crushed panels and enrichment operations such as the use of cation-exchange resins, precipitation and electroplating. Processes for the treatment of CIGS-based panels follow the same sequence, with specific recovery steps for metals In, Ga and Se. Despite the large number of processes for the treatment of end-of-life PV panels available as scientific literature works and patents, few studies presented the development of recycling processes allowing for the treatment of different panel technologies according to the same route. In this work, the experimental results of metal recovery from the implementation of a mechanical and chemical process for the treatment of Si-based and CIGS-type panels were reported. This flexible process (named as Photolife process) was developed in lab scale and demonstrated in pilot scale (within Photolife project, LIFE13 ENV/IT/001033) for the recovery of high-quality glass and metal-bearing products of Ag from Si-based panels and of critical raw materials from CIGS.

Recovery of precious and critical raw materials from end of life photovoltaic panels / Flavia, Padoan; Schiavi, PIER GIORGIO; Baldassari, Ludovica; Moscardini, Emanuela; Toro, Luigi; Altimari, Pietro; Pagnanelli, Francesca. - (2019), pp. 281-298. [10.1201/9780429023545-14].

Recovery of precious and critical raw materials from end of life photovoltaic panels

Flavia, Padoan;Pier Giorgio, Schiavi;Emanuela, Moscardini;Luigi, Toro;Pietro, Altimari;Francesca, Pagnanelli
2019

Abstract

Photovoltaic (PV) technology configures as a competitive technological alternative to convert solar radiation into electricity, and it is expected to provide a fundamental contribution to the transition from traditional fossil fuels to economies based on renewable energy. This technology has been applied since the 1980s, with the first significant installation dating back to the early 1990s. Si-crystalline (mono and poly) panels represent the most consolidated PV technology and have dominated the PV market over the past decades, with 92% of the PV market share. In order to reduce the panel production costs, alternative PV technologies have been developed, including between the panels a thin film of Copper Indium Gallium Selenide (CIGS). PV technologies imply the use of precious and rare metals such as Silver in Si panels and Indium and Gallium in CIGS panels. Available data from the literature reported a range of concentrations in PV panels from 20 to 600 mg/kg for Ag, 80–200 mg/kg of In and 25–310 mg/kg for Ga. Variability of metal concentrations depends on the time of production and specific manufacturing technologies aiming at reduction of production costs: for example, Ag concentration in PV panels is expected to be reduced from 0.14%–0.2% in 2003 to 0.07%–0.16% in 2023. The average lifetime of a PV panel is estimated to be around 25 years irrespective of the considered technology. Since the electric power share from PV installations became relevant starting from the end of nineties, a dramatic increase in the annual flux of end-of-life PV panels can be expected around 2025. Motivated by this forecast analysis, several recycling processes have been proposed to recycle PV panels. The main target of the proposed processes is to meet the material recovery targets set by the relevant regulation (EU, 2012), ensuring, at the same time, economic and environmental sustainability. Many works on PV panel recycling were focused on the treatment of Si-panels and cadmium telluride (CdTe) panels. Treatments of Si modules mostly remove the Al frame and the junction box mechanically or manually, followed by the use of high temperatures in order to modify the characteristics of the solar modules and decompose ethylene-vinyl acetate (EVA), which allows for the subsequent mechanical separation of clean glass and Silicon solar cells. The obtained separated cells can be then chemically treated with acids to dissolve metals, and further purification steps can be performed. Another approach is EVA dissolution by the contact with organic solvents. Cadmium and Tellurium are the main targets of CdTe panel recycling, which typically comprises the acid treatment of crushed panels and enrichment operations such as the use of cation-exchange resins, precipitation and electroplating. Processes for the treatment of CIGS-based panels follow the same sequence, with specific recovery steps for metals In, Ga and Se. Despite the large number of processes for the treatment of end-of-life PV panels available as scientific literature works and patents, few studies presented the development of recycling processes allowing for the treatment of different panel technologies according to the same route. In this work, the experimental results of metal recovery from the implementation of a mechanical and chemical process for the treatment of Si-based and CIGS-type panels were reported. This flexible process (named as Photolife process) was developed in lab scale and demonstrated in pilot scale (within Photolife project, LIFE13 ENV/IT/001033) for the recovery of high-quality glass and metal-bearing products of Ag from Si-based panels and of critical raw materials from CIGS.
2019
Critical and rare earth elements. Recovery from secondary resources
9780367086473
photovoltaic panels; precious metals; critical metals
02 Pubblicazione su volume::02a Capitolo o Articolo
Recovery of precious and critical raw materials from end of life photovoltaic panels / Flavia, Padoan; Schiavi, PIER GIORGIO; Baldassari, Ludovica; Moscardini, Emanuela; Toro, Luigi; Altimari, Pietro; Pagnanelli, Francesca. - (2019), pp. 281-298. [10.1201/9780429023545-14].
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