Sol Systems has completed the 186-MWDC Tilden Solar Project built on more than 1,000 acres of a subsurface coal mine in Southern Illinois.
The $345 million project brings new life to land long shaped by America’s energy history, transforming a complex legacy site into modern clean energy infrastructure that will generate approximately 319 GWh of electricity in its first year. The mines closed in the 1990s and left the area depleted of resources, both natural and financial.
Developing solar on a former subsurface mine presented unique engineering, environmental and permitting challenges, including long-term subsidence considerations and coordination across a significant number of mineral rights owners. Through innovative design solutions and close collaboration with technical, regulatory and community stakeholders, Sol Systems advanced the project from concept to commercial operation.
“Tilden is a compelling example that even the most challenging sites in America, like former coal mines, can be reimagined and repowered as part of our clean energy future,” said Yuri Horwitz, CEO and Founder of Sol Systems. “Sol is committed to creating long-term economic and environmental value for our customers and the communities we operate within. The Tilden Project is part of a 1-GW portfolio of dual use solar projects that Sol will operate in active partnership with local farmers and stakeholders.”
“Tilden presented the team with some distinct challenges, and we’re proud of the teamwork that made it possible,” said Andy Poirot, Vice President at McCarthy Building Companies. “Building on a historic subsurface mine required a level of coordination, engineering precision and problem-solving that you don’t see on a typical solar project. Sol Systems made that possible.”
During construction performed by McCarthy Building Companies, the project created approximately 300 full-time local jobs and is expected to generate a combined $20 million in both tax revenue and local impact investments for the community over its lifetime. Tracking systems were supplied by Nextpower and solar modules provided by Canadian Solar. Financing partners included ING as lender and Churchill Stateside Group as tax equity investor.
Beyond its operational significance, Tilden underscores a broader opportunity across the Midwest and other legacy energy regions: transforming former industrial and extraction sites into modern infrastructure that supports domestic energy production while delivering long-term community benefits.
The story of the Tilden Solar Project is featured in Sol Systems’ short film, Innovation with Integrity: A New Life for the Tilden Mine, which documents the challenges and breakthroughs that brought the project to completion and highlights how technical innovation and community stewardship can work hand in hand.
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