Capitol Lake Plaza sits centrally on Pierre, South Dakota's government plaza. Originally built in 1974, the building underwent major energy renovations after being purchased by the state. SWT Energy installed a ballasted, rooftop photovoltaic array composed of 80, 300kW solar panels.

The system was funded by a grant from the American Recovery and Reinvestment Act. Preliminary estimates showed that by producing a portion of its own power, Capitol Lake Plaza would save the state nearly $37,000 a year on energy costs.