A solar cell is made of two types of semiconductors, called p-type and n-type silicon. P-type silicon is produced by adding atoms such as boron or gallium that have one less electron in their external energy level than silicon. Cadmium is the main ingredient in cadmium telluride (CdTe) cells, a type of photovoltaic panels that convert sunlight directly into electricity. CdTe cells are the largest type available and are the most widely used commercial fine-molecule product.
When sunlight hits these panels, it energizes electrons within surface materials to create an electrical current. Although classified as a natural terrestrial metal, cadmium can be highly toxic if inhaled or ingested. Interaction with this chemical can cause damage to the lungs and internal organs. Another drawback is its cost and inefficiency: only about half of the cadmium used becomes the final product of the film used in cells.
The solar cell manufacturing process involves a number of harmful chemicals. These substances, similar to those used in the general semiconductor industry, include sulfuric acid, hydrogen fluoride, hydrochloric acid, nitric acid, 1,1,1-trichloroethane and acetone. The quantity and type of chemicals used depend on the type of cell and the technology used. Thin-film photovoltaic (TFPV) technology contains a greater number of toxic materials than those used in traditional silicon photovoltaic technology, such as indium, gallium, arsenic, selenium, cadmium and tellurium.
These materials must be handled and disposed of properly to avoid serious environmental and human health problems over time. In a nod to environmental concerns, many owners of used solar panels are already recycling them instead of throwing them in landfills, and therefore getting the residual value from old equipment that would otherwise be thrown away. In these cases, silicon must undergo more chemical processing, where it mixes with copper and hydrochloric acid. The manufacture of photovoltaic devices includes some chemicals that may be toxic or harmful to humanity.
In the manufacturing process, some chemicals are used to prepare silicon and manufacture the wafers for monocrystalline and polycrystalline panels. However, it is important to remember that, even with the inclusion of these and other chemicals, solar energy is a very rare source of energy that does not produce harmful emissions or toxic waste. Gallium arsenide (GaAs) solar cells can use aluminum, indium or phosphorus as p-type or n-type materials. This chapter has demonstrated the potential of some materials and chemicals used in the manufacture of thin-film photovoltaic solar cells and modules to be hazardous.
Amorphous silicon-based solar cells are generally manufactured using the plasma-enhanced chemical vapor deposition (PECVD) technique. And as with most forms of manufacturing (even “clean energy”), chemicals are used throughout the process to produce the final product. This chapter discusses the possibility of chemicals used in the photovoltaic cell manufacturing process being released to the air, the surface of the water and the environment. However, the exposure of nearby residents or other workers would be lower than that of plan workers, since the chemicals would be dispersed into the ambient air after they were released.
. Stanford magazine also points out that solar energy has a higher carbon footprint than wind and nuclear energy. Beyond the inefficient use of these resources from the outset (in the process of manufacturing crystalline silicon from silicon, up to 80 percent of raw silicon is lost), there are numerous human health problems directly related to the manufacture and disposal of solar panels. .