On December 12, 2023, ComEd announced an expansion of its 765 kW Wilton Center substation, which the utility says will support utility-scale onshore wind and solar projects in Illinois and the larger PJM energy market.[1] The substation expansion is expected to be completed in late 2026. The Wilton Center substation, constructed in 1968 near Joliet, Illinois, supports ComEd’s highest voltage transmission lines, which are used for long-distance power transmission because they minimize the amount of power lost as electricity moves from one location to the next. The facility will be expanded by approximately 50%. Work will include adding new circuit breakers, transformers, relay switches, network data, and control systems. When the expansion is completed, the substation should be able to support five wind farms and two solar farms with the capacity for up to 2,450 MW of renewable energy.

Currently, ComEd is currently working on 13 wind projects throughout Illinois, amounting to 3,120 MW of potential wind generation. One of the projects that will be supported by the Wilton Center substation is the 850 MW Heritage Prairie wind farm. The farm, which also includes 300 MW of solar generation, will be the largest wind interconnection in northern Illinois and the largest onshore wind project to date in PJM.

[1] https://www.businesswire.com/news/home/20231212571627/en/ComEd-Expanding-High-Voltage-Substation-in-Wilton-Center-to-Enable-Largest-Cluster-of-Wind-and-Solar-Projects-in-Illinois-and-PJM-Region