Recycling of Photovoltaic modules – ReGCell 2

A. Dsouza1*, K. Sarquah1, G. Beck1,2

1. SRH University of Applied Science, Ernst-Reuter-Platz 10, 10587, Berlin, Germany.

2. ABCircular GmBH, Magnustrasse 11, 12489, Berlin, Germany.

*alan.d`souza@stud.srh-campus-berlin.de

Abstract

The main goal of this experimental work is the delamination and recovery of all materials of thick-film photovoltaic modules. This research work is the extension of the ReGCell 1 process, which used chemical baths to separate the glass of the photovoltaic module.

A photovoltaic panel consists of the following layers. At the top, we have the flat glass, which is of low iron content and has a low reflection. The next layers are the encapsulants, mainly made up of EVA (Ethylene Vinyl Acetate), which encapsulates the silicon cells. And last, we have the Back sheet which is either made up of PVF (Poly Vinyl Fluoride) or PET (Polyethylene Terephthalate). All of this is enclosed in an aluminum frame and metals such as copper and silver is used as connectors. A junction box is present to connect the solar panels to transfer the electricity generated.[1]

Currently, most solar panels are produced from crystalline silicon, which is either in monocrystalline or polycrystalline type. In the current market, the crystalline silicon type photovoltaic module accounts for about 90% of the global photovoltaic panel production. This is mainly because of their high efficiency. The rest of the market is thin-film technologies, which are mainly cadmium telluride, CIGS, and amorphous silicon.[2]

The research work is done in 3 experimental steps as mentioned in figure (1). The first one is the chemical bath, where d-limonene is used. The photovoltaic module is submerged in the chemical bath at a temperature of 60°C. In this step, we are able to recover the glass as well as the back sheet which is PET or PVF.

The next step is the pyrolysis process of the remaining laminate, which are the silicon cells, EVA, and the metal wires at temperatures between 450 - 600°C. This process separates the EVA from the silicon and the metal wires. Also, we obtain gas, oil, and tar as the other pyrolytic products.

The next step is the electrochemical recovery, where are 3-electrode setup is used with a drum as the working electrode. The electrolyte used is 1M Methyl sulphonic acid with the addition of NaCl. The main metals to be recovered from this method are silver and copper.

References

[1] L. Richardson, “What Are Solar Panels Made Of and How Are They Made? | EnergySage,” EnergySage Blog, Dec. 12, 2022. https://news.energysage.com/what-are-solar-panels-made-of-list-of-solar-pv-materials/ (accessed Jan. 04, 2023).

[2] D. S. Philipps, F. Ise, W. Warmuth, and P. P. GmbH, “Photovoltaics Report”.