Why does a segment of the solar energy industry use cadmium in its photovoltaic (PV) modules? This Web site provides a central information clearinghouse for your exploration of this issue, including a forum for discussion—we welcome your input.

Here are some interesting facts about cadmium and cadmium telluride (CdTe) PV modules:

• CdTe is an excellent choice for use as a semiconductor in solar panels because it is perfectly matched to the solar spectrum. Cadmium sulfide provides semiconductor properties, and its transparency allows the sunlight to pass through to the CdTe layer. These characteristics provide the potential for high-efficiency modules with low-cost manufacturing processes.
  
  
• A CdTe PV module contains very little cadmium. In fact, it has less than 0.1% cadmium by weight. One 8-square-foot module contains less cadmium than one size-C NiCd flashlight battery, and the cadmium in the module is in a much more environmentally stable form (i.e., a compound rather than a metal).
  
  
• Because cadmium is encapsulated in the PV module, PV technology provides an effective solution for sequestering cadmium. A by-product of the zinc mining industry, cadmium usually ends up in a slag heap or in NiCd batteries, half of which eventually end up in landfills. PV modules seal the cadmium for the life of the module (20-30 years), at which time the cadmium can be easily recycled.
  
  
• PV modules use natural elements and compounds to generate clean, emissions-free energy. Consumers face much greater hazards from the use of conventional energy, which can produce acid rain, particulates, noxious fumes, carbon dioxide, and small amounts of heavy metals. PV modules produce no pollutants during operation, making them the perfect solution for offsetting emissions (including cadmium) that result from fossil fuel use. The potential for cadmium use in the solar energy industry to ameliorate global climate change cannot be ignored.
  
  
• In the future, using a relatively small amount of cadmium for PV (say, about 2,000 metric tons per year) could change the world's electricity infrastructure; in comparison, the much larger, existing use of cadmium for other applications (about 20,000 metric tons per year) provides trivial value.
  
  
• For more information, download Cadmium Facts and Handy Comparisons
  (PDF 169 KB) (Download Acrobat Reader).