Mulvaney does point out, however, that Germany-based SolarWorld, which has been making PV modules in the United States since 1975, topped the list—a fact the company does not defend or dispute. “It would be surprising if we weren’t the largest waste producer in the state during those years, since we were the largest manufacturer in the state,” says Ben Santarris, a SolarWorld spokesperson.
During those years, the company’s Camarillo, California, plant produced as much as 150 megawatts of modules annually. SolarWorld purchased the Camarillo plant in 2006 from Shell Solar, and upgraded the facility to automate module assembly operations, but closed the plant in 2011 and consolidated all domestic manufacturing at its facility in Hillsboro, Oregon.
“The fact that the AP can do this article and look up public records about our practices is a good thing. It is all part of the robust system of checks and balances that supports our regulatory environment, and pushes American industry to achieve higher standards. We have nothing to hide,” Santarris says. “You can’t say the same about producers operating in China, where there is no transparency.”
Sergio Vasquez, health, safety, and environment and facilities manager for SolarWorld America, says the issue boils down to economics. “We need to use certain chemicals, but chemicals are expensive. The fewer chemicals we use, the more money we save. The less we pollute, the less we pay to mitigate our waste and the less we pay for environmental control equipment. There is no motivation to be wasteful.”
It is no secret that solar manufacturing involves toxic chemicals and heavy metals—such as cadmium, copper, lead, and selenium. Like most industrial chemicals and metals, these materials require special handling and regulation to limit exposure to the environment and workers. Any hazardous byproducts and wastewater must be handled in accordance with local, state, and federal regulations.
The Silicon Valley Toxics Coalition (SVTC), a San Jose-based environmental watchdog organization, calls for the reduction and eventual elimination of these toxic chemicals. In 2009, the group released a white paper that documented the environmental and health hazards associated with solar modules. The report recognized that, although PV modules provide clean energy while in use and can help address global warming, a variety of factors during the manufacturing and disposal of the modules have the potential to damage the environment.
“Modules are designed to live on a roof, in a completely inhospitable environment. They can withstand heat and moisture, and they are pretty solid. The semiconductor material, where the chemicals are housed, is encapsulated. So long as the integrity of the module is not compromised to expose the actual semiconductor, then there’s little risk of the chemicals escaping into the environment,” says Mulvaney, coauthor of the paper, and the technical advisor for the SVTC’s Just & Sustainable Solar Industry campaign.
Today’s most common PV technology—crystalline silicon (c-Si)—is based on silicon semiconductors, and uses manufacturing processes and materials similar to those of the microelectronics industry. As Mulvaney explains, there are three main chemicals of concern related to c-Si production: silicon tetrachloride, hydrofluoric acid, and lead. Silicon tetrachloride is a toxic byproduct of polysilicon production, but most companies have invested in the equipment to recover and reuse it in new silicon feedstock.