Identifying the recycling bottlenecks of crystalline silicon solar panels
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Insinööritieteiden korkeakoulu |
Master's thesis
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Authors
Date
2022-08-22
Department
Major/Subject
Sustainable Energy Conversion Processes
Mcode
ENG3069
Degree programme
Master's Programme in Advanced Energy Solutions (AAE)
Language
en
Pages
90+8
Series
Abstract
The transition towards renewable electricity created a boom in the photovoltaic (PV) technology. This boom leads to accumulation of PV waste, which slowly becomes an issue. Without proper recycling, silver stocks will be depleted, the embedded energy and other materials will be lost in the disposed crystalline silicon (c-Si) solar panels. Therefore, the recycling of c-Si solar panels will become crucial in the future and this thesis aimed to identify bottlenecks that are restricting the recycling today. This work presented an overview of main materials used in c-Si solar panels. Those were found to be: glass, silicon, silver, ethylene vinyl acetate, copper and soldering metals as Sn and Pb, and fluoropolymers. The literature review was supported by an experimental analysis of 2 disposed c-SI solar panels. Elemental analysis using X-Ray Fluorescence and Energy Dispersive X-ray analysis was conducted. Mechanical separation as well as chemical separation combined with thermal separation of the different panel layers were trialed. The componential composition of the 2 panels was established and compared with the literature. Current industrial recycling of c-Si solar panels evolves around shredding, where glass, aluminium alloys and other metals are recovered. Furthermore, it is possible to chemically recover Ag and Cu from the cell residues, but usually materials with high value are lost or downcycled. In this work ways to recover parts with higher value, like intact glass or Si wafers were discussed. Other stages of the recycling hierarchy were also presented in more detail. The described research helped to navigate the identification of the bottlenecks. The main bottlenecks were: 1. encapsulants, 2. low volume of the end-of-life panels, 3. complex structure of the panels. Further identified bottlenecks were: low concentration of precious metals, difficulties with wafer recycling, toxic materials, value and mass mismatch, economic drivers, issue of the technological mindset.Description
Supervisor
Santasalo-Aarnio, AnnukkaThesis advisor
Akulenko, Elena S.Miettunen, Kati
Keywords
crystalline silicon solar panels, recycling, recycling bottlenecks, PV encapsulants, material analysis