Illinois Deregulated Energy Market Explained

Illinois runs a competitive, or "deregulated," market for commercial electricity. That single fact shapes almost every decision a business makes about its energy costs, yet the mechanics are widely misunderstood. This guide explains how the market is actually structured, who the players are, and what deregulation does and does not change on your bill.

What "deregulated" actually means in Illinois

Before the late 1990s, an Illinois business bought both the delivery of electricity and the electricity itself from a single regulated utility at a rate set by the state. There was no choice of supplier. The Electric Service Customer Choice and Rate Relief Law of 1997 changed that by separating two things that had always been bundled together:

• Delivery — the poles, wires, transformers, meters, and the crews who maintain them and restore power after an outage.
• Supply — the electricity commodity itself, generated and sold into the grid.

Delivery stayed a regulated monopoly. There is only one set of wires running to your building, and it would make no sense to duplicate them, so the delivery utility remains the sole provider and its rates are approved by regulators. Supply, by contrast, was opened to competition. Eligible commercial customers can now buy their electricity supply from a licensed alternative retail electric supplier (ARES) or stay on the utility's default service.

This is the core idea to hold onto: deregulation made supply competitive while leaving delivery regulated. Your commercial electricity bill reflects both halves.

The regulated side: your delivery utility

Two investor-owned utilities deliver most commercial electricity in the state:

• ComEd serves northern Illinois, including the Chicago metropolitan area. Its region operates within the PJM Interconnection wholesale market.
• Ameren Illinois serves much of central and southern Illinois. Its region operates within the MISO (Midcontinent Independent System Operator) market.

No matter which supplier you choose, ComEd or Ameren still delivers the power, maintains the lines, reads your meter, sends (or coordinates) your bill, and answers outage calls. Switching suppliers never changes the reliability of your service or who shows up when the power goes out. It changes only the supply line item.

Some Illinois communities are served by municipal electric systems rather than ComEd or Ameren. Naperville (through the Illinois Municipal Electric Agency) and Springfield (through City Water, Light & Power) are two examples. Customers in those systems do not have ARES choice — they buy from the municipal utility. Knowing which category you fall into is the first step, and our Illinois overview breaks down the territories.

The competitive side: suppliers and default service

If you are an eligible ComEd or Ameren commercial customer, you have two paths for supply:

1. Stay on default (utility) service. You take supply that the utility provides through the state procurement process. This is the option you have automatically if you never sign a competitive contract.
2. Choose a licensed ARES. You sign a supply contract with a competitive supplier for a defined term, price structure, and set of terms.

Many licensed suppliers compete for commercial load in Illinois. Rather than trust any single company's marketing, verify licensure through the state's official list at plugin.illinois.gov and the ICC. For a fuller walkthrough of eligibility and enrollment mechanics, see how Illinois commercial electricity choice works.

The two agencies that make the market run

Two state bodies do most of the governing, and confusing them is a common mistake.

The Illinois Commerce Commission (ICC)

The ICC is the regulator. It licenses ARES suppliers, approves the delivery rates that ComEd and Ameren charge, oversees consumer protections, and handles complaints. When you want to confirm that a supplier is legitimate or understand what a utility is allowed to charge for delivery, the ICC (icc.illinois.gov) is the authority.

The Illinois Power Agency (IPA)

The IPA is the procurement agency. It buys electricity supply on behalf of eligible customers who have not chosen a competitive supplier — the default-service customers. The IPA runs procurement events and, through that process, the utility's price to compare is established. That price to compare is the benchmark a competitive offer should be measured against. We cover it in depth in the price to compare and when utility supply wins, and the agency's own materials live at ipa.illinois.gov.

What this means for your business

Because supply is competitive and delivery is not, a few practical truths follow:

• You can only shop the supply portion. Delivery charges, riders, and taxes are set by the regulated utility and apply no matter what you do on the supply side. Evaluating a supplier offer means comparing supply against supply — its price against the utility's price to compare — not against your whole bill.
• A wholesale auction price is not your bill rate. Headlines about PJM or MISO capacity auctions describe wholesale markets. Those results filter into retail prices in complex ways, but an auction clearing price is never the rate you pay per kilowatt-hour.
• Doing nothing is a decision. If you never sign a competitive contract, you remain on default service at the price to compare. That is a legitimate choice, and sometimes the better one — but it should be a choice you make on purpose after comparing, not by neglect.

Good procurement in a deregulated market is disciplined comparison, not a search for a magic number. Understand your load, know your price to compare, verify any supplier's license, and read the contract terms — bandwidth, term, and renewal language — before you sign. Our commercial energy procurement resources walk through that process step by step, and commercial natural gas choice follows a parallel structure on the gas side.

Sources

• Plug In Illinois — official electric choice information
• Illinois Commerce Commission
• Illinois Power Agency

This article is educational and does not promise any particular savings. Whether a competitive supply offer beats default service depends on your usage, the current price to compare, and the specific contract terms available to you.