Double Black Diamond Solar

Double Black Diamond Solar is the largest operating solar facility in Illinois and east of the Mississippi River. The 593 MWac / 800 MWdc solar facility, west of Springfield, Illinois, provides reliable, renewable energy for the city of Chicago and offsets the equivalent emissions of more than 100,000 Illinois households per year. As part of the project, McCarthy also completed a substation on site featuring three main power transformers – one of the largest ever completed by McCarthy – that tied into the Ameren switch yard.

By sourcing over 1.6 million U.S.-made panels, solar trackers, and 19,382 steel piles, the project reduced supply chain risk, supported domestic manufacturing, and qualified for Inflation Reduction Act (IRA) domestic content incentives—providing timely delivery and long-term energy reliability for Swift Current.

Approximately 70% of the electricity used by city-run facilities—including major hubs like O’Hare and Midway airports—will come from Double Black Diamond. Other reputable organizations, such as Cook County, CVS Health, Loyola University, PPG, State Farm, and TransUnion will also benefit from DBD, under a power purchasing agreement through Constellation NewEnergy, Inc. 

Spanning both Sangamon and Morgan Counties, the project team collaborated with Swift Current and the County Representatives to gain all permits and approvals to construct the project. The project was delivered using a phased-delivery approach, with 50% of the plant being turned over to the client seven months early. As the plant continued to commission the subsequent circuits, 50 MW portions of the plant continued to be turned over early to the client months prior to the contracted COD date.