Data Center Power Deals Spark Ratepayer Fights in Wisconsin, Illinois
Two major data center developers are clashing with utilities over who pays for the transmission and distribution buildout needed to power their projects, Utility Dive reports, citing filings made at the Federal Energy Regulatory Commission in August 2026.
In Wisconsin, Microsoft told FERC on Aug. 21 that agreements between American Transmission Co. and Wisconsin Electric Power Co. covering its Mount Pleasant data center campus contain “errors, contradictions and inconsistencies” and fail to shield ratepayers from cost shifts. In Illinois, PowerHouse Hillwood on Aug. 14 accused Commonwealth Edison of using “monopoly power as a bludgeon” after ComEd canceled a transmission security agreement tied to a planned 1.8-GW, $20 billion data center in Joliet.
Market Impact
Both disputes trace back to a June 2026 FERC order finding that grid operators’ large-load interconnection rules may be inadequate. FERC’s “show cause” orders directed regional transmission organizations and independent system operators to fix five issues, including preventing cost shifts to existing ratepayers and improving transparency into transmission costs. FERC extended the RTOs’ and ISOs’ response deadline to mid-November.
Microsoft says it was excluded from negotiations on the four amended Large Load Project Commitment Agreements and the Minimum Transmission Charge Agreement filed by ATC, and that the proposed minimum transmission charge lacks a mechanism to stop WEPCo retail customers from picking up infrastructure costs, potentially forcing large-load customers to pay twice. Microsoft has asked FERC to order settlement talks. ATC counters that its agreements are “directly responsive” to FERC’s concerns, while the Wisconsin Public Service Commission called the filings an improvement but “far from fully responsive” to the show cause order.
In Illinois, PowerHouse Hillwood’s fight with ComEd centers on the timing of a security deposit and has already spawned a lawsuit. ComEd also canceled a related retail service agreement pending before the Illinois Commerce Commission. PowerHouse Hillwood argues FERC needs standardized pro forma agreements for large-load interconnections, similar to those governing generator interconnections, to prevent utilities from using discretionary contract terms against developers.
What It Means for Subcontractors
- Electrical, transmission and substation contractors bidding on work tied to the Mount Pleasant, Wisconsin campus should expect possible delays if FERC orders settlement judge proceedings between Microsoft, ATC and WEPCo before construction terms are finalized.
- Contractors tracking the 1.8-GW Joliet, Illinois data center (a $20 billion PowerHouse Hillwood project) should watch the FERC docket on ComEd’s canceled transmission security agreement, since the litigation could stall issuance of subcontract packages for site electrical and interconnection work.
- Firms working large-load interconnection projects nationally should monitor FERC’s mid-November deadline for RTO/ISO responses to the June 2026 show cause order, since new cost-allocation and transparency rules could reshape how transmission owners structure agreements with data center developers going forward.
- Because these disputes hinge on unresolved cost-shift and rate-design questions, timelines for grid-tied construction contracts tied to hyperscale campuses remain uncertain until FERC rules on both the Wisconsin agreements and the ComEd cancellation.
