in 2009 wacker announced plans to construct a new solar-grade polysilicon production facility in charleston, a small city in bradley county, tennessee. groundbreaking occurred on april 8, 2011, and the plant became operational in april 2016, costing approximately us$2.5 billion and making it the largest-ever single private investment in the state of tennessee. in june 2017, a us$150 million secondary expansion was announced that would allow the plant to manufacture pyrogenic silica. this expansion was completed in october 2019, adding 50 new jobs to the plant.