Silicon-based PV cells are the most widespread solar photovoltaic technology used. Most solar panels have a glass front that protects the PV cell and an aluminum or steel frame. Research shows that “leaching of trace metals from modules is unlikely to present a significant risk due to the sealed nature of the installed cells.” Some solar modules use cadmium telluride (CdTe). Cadmium compounds are toxic, but studies show that such compounds cannot be emitted from CdTe modules during normal operation or even during fires. Industrial incineration temperatures, which are much higher than grassfires, are required to release the compounds from the modules.