Illinois has two main utilities: ComEd (Chicago + northern IL) and Ameren Illinois (central + southern). Both offer supplier choice through ICC-certified ARES (Alternative Retail Electric Suppliers). ComEd standard offer reset in June 2026 to 9.4 cents per kWh. ARES locked rates come in at 8.0 to 8.9 cents per kWh. The savings window in IL is smaller than in PJM states because ComEd procurement is competitive and the SO is already low.
ComEd vs Ameren Illinois
ComEd (Commonwealth Edison) serves Chicago metro and 11 northern Illinois counties. Largest IL utility by customer count. Ameren Illinois serves central and southern Illinois including Springfield, Peoria, Champaign.
Each utility runs its own procurement auction for default service. The ComEd standard offer adjusts on June 1; Ameren adjusts on October 1.
Why Illinois savings are smaller
ComEd standard offer is set through competitive auction by the Illinois Power Agency. The resulting price is closer to wholesale than typical utility default service in other states.
2026 ComEd SO: 9.4 cents per kWh. ARES locked rates: 8.0 to 8.9 cents per kWh. Savings: 0.5 to 1.4 cents per kWh, or roughly 6 to 12 percent.
Illinois municipal aggregation
Many Illinois municipalities run opt-out aggregation programs through the ICC. The aggregation bundles residential supply contracts for the participating municipality.
Chicago suburbs (Naperville, Schaumburg, Wheaton, etc.) have active aggregation. Chicago proper does not aggregate at the city level but several wards have explored it.
Lock the rate before the next reset.
Seenra runs the supplier shortlist in 5 minutes. No credit pull, no on-site visit, no service interruption. Forever free for households.
Get my fixed-rate quote →Common questions
Quick answers from the editorial desk
How does ARES differ from municipal aggregation?
What is the IL aggregation opt-out window?
Can Chicago residents aggregate?
How do I break out of an aggregation contract?
Further reading