Silicon photovoltaic panels: characterization and recycling possibilities

The growing demand for energy combined with the scarcity of non-renewable energy sources has led to the research of alternative energy sources capable of replacing the traditional ones with the least environmental impact. Among these alternatives, solar energy is very important, since it is a virtually inexhaustible source and generates relatively small environmental impact compared to other traditional generation sources. The collection of solar energy and its conversion into thermal or electrical energy is only possible with photovoltaic panels. These panels have a limited lifespan of 20 -25 in average and will eventually be replaced by new ones and thrown away. Thus, in the near future, large amounts of solar modules will become electronic waste. In order to retrieve important raw materials, reducing production costs of new panels and environmental impacts, recycling such materials is important.

In this paper, photovoltaic module components were characterized through visual inspection, x-ray fluorescence, energy dispersion spectroscopy and atomic absorption spectroscopy. The glass was identified as ordinary glass (soda-lime glass), which can be reused without any previous treatment. The metallic filaments were identified as tin-lead coated copper, which can be recycled through known pyrometallurgical processes. The modules' cells were made of silicon and had silver filaments attached to it. The silicon and silver were separated and recovered through chemical processes. The modules' frames were identified as aluminium and can be recycled without any previous treatment.

Moreover, different segregation methods have been studied in order to separate the different components with the smallest environmental impact. Chemical, pyrometallurgical and mechanical methods have been tested. Pyrometallurgical methods have shown the most promising results so far. A detailed description of the separations methods and the experiments' layouts will be given.