Commercial Electricity in Illinois: Rates, Suppliers & Procurement

Illinois businesses in the ComEd and Ameren Illinois service areas can buy their electricity supply from a competitive retail supplier or stay on utility default service. The delivery utility does not change. This page explains what actually drives a commercial electricity price, how supply and delivery differ, and what a genuine quote requires — before you hand over any account information.

Who this is for

Facility managers, operations managers, controllers, and CFOs responsible for one or more commercial or industrial accounts in Illinois. It applies to businesses that pay a demand (kW) charge, run multiple meters, or have a supply contract approaching renewal — not to residential accounts.

Where retail choice applies (and where it does not)

Most of northern Illinois is served by ComEd for electricity delivery; central and southern Illinois is largely served by Ameren Illinois. Eligible commercial customers in both territories can contract with a licensed Alternative Retail Electric Supplier (ARES) or remain on the utility's default supply, per the Illinois Commerce Commission.

Some Illinois cities own their electric systems and buy power on a full-requirements basis, so there is no separate supplier to choose — Naperville (city-owned electric utility supplied through IMEA) and Springfield (City Water, Light & Power) are the clearest examples in this region. If a location is served by a municipal utility, competitive electricity supply does not apply; the useful conversation there is usage, efficiency, and — where relevant — natural gas.

Supply vs. delivery: the distinction that prevents overstated savings

A supplier contract can change the supply economics — energy plus capacity, transmission, line losses, any renewable obligation, ancillary services, and supplier fees. It does not replace the utility's delivery charges (distribution, metering, riders, and taxes), which remain on the bill under regulated tariffs.

The most common commercial energy mistake is applying a supply-price difference to the entire bill. Delivery is often a large share of a commercial bill, so a change in the supply rate moves only part of the total. Read a bill in groups — account/meter, usage and demand, supply, and delivery/other — before comparing anything.

What affects a commercial electricity price

• Usage and load shape — total kWh and when it is used across the day and year.
• Demand (kW) — many commercial rate classes bill a demand charge on peak usage.
• Capacity obligation — a facility's capacity tag (PLC in the PJM/ComEd zone) can be a meaningful cost driver carried into supply pricing.
• Contract term and start date — different terms and delivery-date windows price differently.
• Meter count, credit, and product structure — fixed, index, or block-and-index each carry different risk.
• Market timing and applicable taxes.

Because these vary by account, no single "current commercial rate" applies to every Illinois business. Utility default supply and competitive offers are also different things and should be compared as such — see the price-to-compare guide.

Contract structures at a glance

• Fixed — a set supply price per kWh for the term; budget certainty for the components the contract includes, but pass-throughs and change-in-law terms still need review.
• Index / pass-through — supply tracks a market index; potential upside with more month-to-month variability.
• Block-and-index / hedged — a portion locked, the remainder floating; used to balance certainty and flexibility on larger loads.

No single structure is always the least expensive. The right one depends on the account's risk tolerance, load, and budget cycle.

What a real quote requires

A useful, executable quote starts with a recent bill and account number, the service address and utility, 12 months of usage (kWh and billed kW where applicable), and the current contract's end date. Larger or load-shape-sensitive accounts benefit from interval data. Anything priced without this is indicative only. See how procurement works for the full sequence and how to compare offers apples-to-apples before signing.