CHARLESTON, Tenn. (AP) - Wacker Polysilicon officials say they have reached a milestone in construction at their solar products plant in Charleston, Tenn.

Precast walls are being installed at the three largest buildings of the plant. A company spokesman said the walls allow for the installation of a sophisticated system for producing hyperpure polysilicon.

Some 700 construction workers are on site most days.

Production at the plant is scheduled to begin in 2014. The $1.5 billion plant will employ approximately 650 full-time workers.

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