Illinois utility provider Commonwealth Edison (ComEd) has safely brought two new 345 kV transmission substations online to support its energy grid.

According to the company, these new substations will enable the interconnection of up to 550 MW of wind generation in LaSalle and Woodford counties. The expansion follows spiked electricity bills for Illinois ratepayers, driven by rising energy supply costs in the PJM Interconnection wholesale market.

PJM, the nation's largest electric grid operator, manages a high-voltage system powering 65 million people in 13 states and Washington, D.C., including ComEd’s Northern Illinois service area.

To help offset these rising rates, ComEd is accelerating infrastructure investments in strategies like substations to integrate more renewable energy generation. Within the next two years, two future wind farms, Osagrove Flats (150 MW) and Panther Grove (400 MW), will leverage this new capacity.

This builds on ComEd's targeted grid expansion efforts, such as the 138 kV substation constructed in 2022 at the U.S. Department of Energy’s Argonne National Laboratory to ensure reliable energy for critical research.

According to ComEd, the new substations will support up to 550 MW of expected wind generation to come online between 2026 and 2027—an amount equivalent to the capacity needed to power roughly 264,000 homes annually.

“ComEd is committed to delivering the reliable, modern grid Illinois needs to facilitate renewable energy growth, advance the state’s economic development goals and deliver more affordable power for our customers,” said ComEd CEO and President Gil Quiniones in a statement.

ComEd notes that the substation project, which began in 2023, was completed more than four months ahead of schedule. This reportedly included the installation of 16 new transmission towers, over 58 miles of fiber and nearly half a mile of new conductor to further enhance system reliability.

To date, ComEd has more than 1.7 GW of distributed energy resources (DERs) tied to the regional grid. The utility is expanding its tech-driven DER management platform to further accelerate these deployments and increase accessible, affordable clean energy for customers.

This month, ComEd celebrated a company milestone, delivering 65,286 MWh of energy savings to its customers last year. The achievement marked a key step in the utility’s mission to advance voltage optimization (VO).