Illinois has a large data center market around Chicago and plenty of farmland with transmission downstate. The north is served by ComEd in PJM; much of central and southern Illinois is in MISO. ComEd has published detailed land requirements for the substations large loads need, which helps buyers size a site before talking to the utility. Invariant sources Illinois sites off-market and lists nearby sites in Indiana, Wisconsin, Iowa and the Midwest.
Before you start
- Northern Illinois (ComEd) is in PJM; central and southern Illinois are largely in MISO.
- ComEd’s 2026 guidelines call for about 3.1 acres for a 138 kV interconnection substation and 8.5 to 16.5 acres at 345 kV.
- The Chicago market is constrained; downstate sites trade power headroom for distance from the metro.
- Invariant lists nearby sites in Indiana, Wisconsin, Iowa and the Midwest.
Sites near Illinois from our inventory
Invariant has no public Illinois listing today. We source Illinois sites off-market for buyers who send requirements. These sites in neighboring states are available now. Specs are as marketed by the owner and are checked against utility documents before any introduction.
| Region | Power | Land | Timing |
|---|---|---|---|
| Indiana | 200 MW, load study done | ~80 acres | Substation planned |
| Wisconsin | 150 MW built, 80 MW now | 130 ready acres | Now |
| Midwest | 85 MW brownfield | ~20 acres | Now |
| Iowa | 20 MW to 500 MW+ PPA site | Non-zoned | Phased |
Exact locations, the utility documents behind each MW figure and pricing are shared on a call. We also hold sites that are not listed publicly; owners ask for discretion and a site that is shopped everywhere loses value.
ComEd’s substation rules
ComEd’s January 2026 guidelines call for at least 784 by 472 feet, about 8.5 acres, for a 345 kV interconnection substation on one line, expandable to about 16.5 acres, and about 3.1 acres at 138 kV, all before stormwater detention. The station must be reachable from at least two sides for future lines and sit within half a mile of the existing line. Those rules decide which corner of a parcel actually works.ComEd via PJM
Two grids in one state
Because Illinois is split between PJM and MISO, two sites an hour apart can face different study processes, capacity markets and timelines. Confirm the serving utility and grid operator before comparing them.Federal Energy Regulatory Commission
How to screen a Illinois data center site
- Confirm the serving utility and the grid operator, then ask which document backs the MW: a will-serve letter, a load study or a signed agreement.
- Check that the substation has headroom for your load under contingency. Distance to a line is not capacity.
- Screen the county and any city that could annex the site for moratoriums, recent denials and the zoning path.
- Work out usable acres after wetlands, floodplain, slope, easements and setbacks, and reserve room for the substation.
- Kill sites that are already claimed, operating for someone else, contaminated or owned by an environmental liability buyer before spending on parcels.
Invariant runs this screen on every Illinois site before an introduction and grades the result A, B or C by power evidence. Tell us your MW and date and we will send the Illinois sites that fit, including off-market ones.
Browse data center sites by size and state
Questions that come up.
How much land does a data center substation need in Illinois?
ComEd’s 2026 guidelines call for about 3.1 acres at 138 kV and about 8.5 acres at 345 kV on one line, expandable to about 16.5 acres, before stormwater detention.ComEd via PJM
Is Illinois in PJM or MISO?
Both. ComEd territory in northern Illinois is in PJM. Much of central and southern Illinois, served by Ameren and others, is in MISO.ComEd via PJMFederal Energy Regulatory Commission
How do I find a data center site in Illinois?
Start from power evidence, not land: confirm the serving utility, the document behind the MW and substation headroom, then screen local approval and usable acres. Invariant does this for buyers and sources Illinois sites off-market, with nearby sites at 200 MW, load study done, 150 MW built, 80 MW now, 85 MW brownfield, 20 MW to 500 MW+ PPA site. Book a call or call (628) 220-8972.
Sources and references.
Site specifications are as marketed by the seller and are checked against utility documents before any introduction. Public sources checked on . The location, equipment, and operating plan determine which requirements apply to a project.
- ComEd via PJMComEd guidelines on land requirements for interconnection substations ↗
- Federal Energy Regulatory CommissionElectric power markets ↗
- PacesGrid planning for data centers and transmission investment ↗
- U.S. Energy Information AdministrationIllinois state energy profile ↗