Crystalline silicon is the basic element from which the majority of the world's solar panels are made. The solar panel industry has been looking to break its dependence on this singular technology. The use of Cadmium telluride (CdTe) in the manufacture of solar cells has grown considerably over the years. It is now second to silicon for the manufacture of solar cells.
Cadmium and Telluride
Cadmium and telluride are the byproducts of smelting zinc ores and refining copper, respectively. In traditional solar panel technologies, silicon wafers are wired or welded together. In contrast, possessing semi-conductive properties, the cadmium and telluride are applied as a thin layer to a pane of glass, along with busbars and wires that conduct away the generated electricity.
How Does the Cadmium Telluride Technology Compare With Silicon?
Cadmium Telluride Solar Cells Are Generally Less Efficient
CdTe solar cells are generally less efficient than crystalline silicon devices. The record efficiency for a laboratory CdTe solar cell is 22.1% by First Solar. First Solar also reported its average commercial module efficiency to be approximately 18% at the end of 2020. In contrast, advances in solar technology has seen a continuous rise in efficiency ratings of mass-marketed solar panels from just 12% to more than 24%. Regardless, just like with other alternatives to silicon, there is interest in developing novel manufacturing methods that could improve on the efficiency of CdTe cells.
They Are Easy and Cheap to Manufacture
CdTe thin-film solar cells can be manufactured quickly and inexpensively, and this their great attraction. In terms of cost per kilowatt of installed capacity, it represents a better economic value than silicon based solar cells.
They Come With Environmental Concerns
Cadmium and tellurium are toxic and carcinogenic themselves, but CdTe forms a crystalline lattice that is highly stable, and is several orders of magnitude less toxic than cadmium itself. The possibility for broken modules to have high cadmium leakage in the soil is very unlikely as the hazardous materials within them are encased within two layers of glass. Also, they come with the lowest carbon footprint. In addition, they are completely recyclable.
Regardless, during production and when disposed, there are concerns that it could impact the health of workers and if not recycled immediately after use, the ecosystem. Accidents in production facilities or less efficient production facilities could cause largescale environmental hazards. They also have rather poor biodegradability too.
Tellurium Is A Rare Element
Cadmium is a relatively abundant element. On the other hand, Tellurium (Te) is an extremely rare element. According to USGS, the global tellurium production in 2007 was 135MT. Most of the supplies used in the manufacturing process come as a by-product of copper, with smaller amounts from lead and gold. One gigawatt (GW) of CdTe PV modules would require about 93MT. This unavailability of tellurium has placed a limit on how many panels can be produced with this material and it is the major factor deciding the price of CdTe panels.
PEROVSKITE SOLAR CELLS: THE FASTEST GROWING FRONTIER OF SOLAR CELL OPTIMIZATION
A major determinant of efficiency is the type of material and technology used in making the solar cells. Advances in solar technology has seen a continuous rise in efficiency ratings of mass-marketed solar panels from just 12% to almost 24%. Yet at the present, much of the solar industry research and development effort revolves around developing more efficient solar cells. These efforts are driven by the need to harvest more electricity from the solar cells per installation space. Supported by new technologies, sustained research and development efforts, effective business models, innovative policies and access to capital, the solar industry is a dynamic one that continues to push back on existing limitations.
The most important breakthrough in solar cell technology in recent years is the optimization of perovskite solar cells. The technology has developed rapidly from 3% in efficiency in 2006 to 25% today making it the most exciting and talked-about thing in the solar community.
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