Solvent versus thermal treatment for glass recovery from end of life photovoltaic panels: Environmental and economic assessment

Abstract

End of life photovoltaic panels of different technologies (poly crystalline Si, amorphous Si, and CdTe) were treated mechanically in pilot scale by single shaft shredder minimizing the production of fine fractions below 0.4 mm (<18% weight). Grounded material was sieved giving: an intermediate fraction (0.4-1mm) of directly recoverable glass (18% weight); a coarse fraction (which should be further treated for encapsulant removal), and fine fractions of low-value glass (18%), which can be treated by leaching for the removal of metal impurities. Encapsulant removal from coarse fraction was successfully performed by solvent treatment using cyclohexane at 50°C for 1h giving high-grade glass (52% weight), which can be reused for panel production.Experimental results of solvent treatment were compared with those from thermal treatment by economic analysis and Life Cycle Assessment, denoting in both cases the advantages of solvent treatment in recovering high-value glass.

Remanufacturing end‐of‐life silicon photovoltaics: Feasibility and viability analysis

“…In contrast, glass recycled via thermal methods typically is highly contaminated with metals and is therefore of lower value. 34 The use of 'solar-grade' glass, prepared via solvent-based processing, can impart additional benefits when considering second-life manufacturing. Further experimental research is required to evaluate the performance of the second-life glass to better estimate its economic benefits.…”

“…29,[31][32][33] Instead of consuming significant amounts of energy to extract high-purity silicon from silicon raw material (i.e., sand), the alternative supply route, recovering high-purity silicon from EoL modules, only consumes 2-30 kWh. 14,29,34 Recovered silicon can be remelted into SoG-Si (99.9999% purity), with an additional electricity input of 10-20 kWh/module, 15,28 or the silicon wafers can be reused directly if they are recovered intact. 25,[35][36][37] As a result, reusing silicon from EoL modules to replace virgin material can reduce by more than 60% the energy required and greenhouse gas emissions from manufacturing while significantly reducing the metal depletion burden of PV module manufacturing.…”

Development and Techno-Economic Analysis of an Advanced Recycling Process for Photovoltaic Panels Enabling Polymer Separation and Recovery of Ag and Si

“…Considering that main recycling targets in a Si-crystalline PVP are glass, photovoltaic cells and metals, including panel frames (Al) and current collectors (Cu and Ag) [17], the following two observations should be taken into account: (i) the aluminum frame and front glass represent more than 80% of the PVP total weight and (ii) 80% of the overall PVP value is associated to the metals used in PV cell and electric contacts (mainly Si, Cu, and Ag). This means that in order to guarantee the economic sustainability of the recycling process, metals of cell and contacts need to be recycled together with glass and frames (Figure 1).…”

“…A literature survey highlights that the difficulties encountered in the degradation of the encapsulant polymer (typically polyethylene-vinyl-acetate (EVA)) represent a major obstacle to the separation of the EOL-PVP components and thus to the efficient recovery of different valuable fractions [5]. (69-75%), polymers (7-15%), PV cell (3%), and metallic filaments (1%) [5,17,18].…”

“…[20]. However, these processes are generally defined as 'downcycling' because they can meet the requirements of the EU directive by recovering only low-value fractions (e.g., impure fine-sized glass fractions [17]). This is mainly caused by the fine milling operations required to separate the various EOL-PVPs components from the encapsulant Figure 1.…”