Chemical treatment of crystalline silicon solar cells as a method of recovering pure silicon from photovoltaic modules (original) (raw)

Abstract

Photovoltaic technology is used worldwide to provide reliable and cost-effective electricity for industrial, commercial, residential and community applications. The average lifetime of PV modules can be expected to be more than 25 years. The disposal of PV systems will become a problem in view of the continually increasing production of PV modules. These can be recycled for about the same cost as their disposal. Photovoltaic modules in crystalline silicon solar cells are made from the following elements, in order of mass: glass, aluminium frame, EVA copolymer transparent hermetising layer, photovoltaic cells, installation box, Tedlar Ò protective foil and assembly bolts. From an economic point of view, taking into account the price and supply level, pure silicon, which can be recycled from PV cells, is the most valuable construction material used. Recovering pure silicon from damaged or end-of-life PV modules can lead to economic and environmental benefits. Because of the high quality requirement for the recovered silicon, chemical processing is the most important stage of the recycling process. The chemical treatment conditions need to be precisely adjusted in order to achieve the required purity level of the recovered silicon. For PV systems based on crystalline silicon, a series of etching processes was carried out as follows: etching of electric connectors, anti-reflective coating and n-p junction. The chemistry of etching solutions was individually adjusted for the different silicon cell types. Efforts were made to formulate a universal composition for the etching solution. The principal task at this point was to optimise the etching temperature, time and alkali concentration in such a way that only as much silicon was removed as necessary.

Key takeaways

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  1. Chemical treatment is essential for recovering high-purity silicon from crystalline silicon solar cells.
  2. The average lifetime of photovoltaic modules exceeds 25 years, necessitating effective recycling strategies.
  3. Optimized etching processes require precise control of temperature, time, and solution concentration.
  4. Universal etching solutions must be tailored to specific PV cell types due to composition variability.
  5. Recycling pure silicon can lead to economic and environmental benefits, mitigating future waste issues.

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References (6)

  1. Wambach K., Schlenker S., Springer J., Konrad B., Sander K., Despotou E., et al., PV cycle -on the way to a sustainable and efficient closed loop system for photovoltaics. In: 22nd European Photovoltaic Solar Energy Conference, Milan, Italy 2007.
  2. Ro ¨ver I., Wambach K., Weinreich W., Roewer G., Bohmhammel K., Process Controlling of the Etching System HF/HNO 3 /H 2 O. In: 20th European Photovol- taic Solar Energy Conference 2005, Barcelona, Spain.
  3. Mu ¨ller A., Ro ¨ver I., Wambach K., von Ramin-Marro D.W., Recovery of high value material of different photovoltaic technologies. In: 22nd European Photovoltaic Solar Energy Conference, 3-7 September, Milan, Italy 2007.
  4. Acker J, Henssge A. Chemical analysis of acidic silicon etch solutions II. Determi- nation of HNO 3 , HF, and H 2 SiF 6 by ion chromatography. Talanta 2007;72:1540-5.
  5. Wolf HF. Semiconductors. WNT Warszawa; 1975.
  6. Van Zant P. Microchip Fabrication: A Practical Guide to Semiconductor Processing. New York: McGraw-Hill Professional Publishing; 2000.