Illinois Energy Aggregation Programs: How Municipal Aggregation Can Lower Your Bill

Hundreds of Illinois municipalities have done the hard work of negotiating competitive electricity rates on behalf of their residents — and many Illinois consumers are benefiting from those rates right now without even knowing it. Illinois energy aggregation programs represent one of the most effective and frictionless ways to access competitive electricity pricing in the state.

Municipal energy aggregation (also called community aggregation) uses the collective purchasing power of an entire community to negotiate electricity supply contracts that individual households could never match on their own. When a village of 15,000 households pools its demand, it becomes a major commercial buyer — giving it leverage over suppliers that a single homeowner simply doesn't have.

But like any energy program, municipal aggregation comes with nuances, limitations, and potential pitfalls. Not every program saves money. Not every contract is well-structured. And the opt-out mechanics can catch inattentive residents off guard. This guide explains exactly how Illinois municipal aggregation works, how to find out if your town participates, what to do if the program isn't serving you well, and the alternatives available if it isn't. By the end, you'll know whether your town's aggregation program deserves your participation — or whether you'd be better off arranging your own supplier.

What Is Illinois Municipal Energy Aggregation and How Does It Work?

Illinois municipalities gained the legal authority to aggregate electricity customers under the Illinois Power Agency Act (220 ILCS 5/16-103). This law allows cities, villages, and townships to procure electricity supply on behalf of their residents through a competitive process — essentially acting as a collective bargaining agent for energy.

The Mechanics of Aggregation

Here's how a typical Illinois municipal aggregation program operates:

  1. Voter or council authorization: The municipality votes to authorize an aggregation program. Opt-out programs require a referendum; opt-in programs can be established by ordinance alone.
  2. Request for Proposals: The municipality (typically through an energy consultant) issues an RFP to ICC-licensed ARES, soliciting competitive electricity supply bids for the community's combined load.
  3. Supplier selection: After reviewing bids, the municipality selects a supplier based on price, contract terms, renewable energy options, and financial stability.
  4. Customer notification: Residents receive a notice explaining the program, the rate, and their right to opt out (for opt-out programs) or opt in (for opt-in programs).
  5. Enrollment and supply: Eligible residents are enrolled and begin receiving electricity supply from the aggregation supplier, while ComEd or Ameren continues to deliver the electricity.

Opt-Out vs. Opt-In Programs

Illinois allows both opt-out and opt-in aggregation structures:

  • Opt-out programs (more common): All eligible customers are automatically enrolled unless they actively decline. These programs achieve 60–80% participation rates, giving the municipality significant purchasing leverage. If you do nothing, you're enrolled.
  • Opt-in programs (less common): Customers must proactively enroll. Participation rates are typically 10–30%, limiting the program's bargaining power and often resulting in less competitive rates.

Who Is Eligible?

Most Illinois aggregation programs cover:

  • Residential customers within the municipality's borders
  • Small commercial customers (typically under 15,000 kWh/month)

Customers who already have an individual ARES contract are typically excluded from enrollment until their existing contract expires. Customers with low-income utility assistance programs may also be excluded to protect their current rate protections.

How Illinois Energy Aggregation Programs Can Slash Your Monthly Electric Bill

The core value proposition of municipal aggregation is simple: collective purchasing power translates to lower rates. But whether that value is actually delivered depends on several factors specific to your municipality's program.

The Scale Advantage

A municipality enrolling 10,000 residential accounts represents roughly 90–120 million kWh of annual demand — the equivalent of a medium-sized commercial or industrial buyer. At that scale, suppliers compete aggressively for the contract, and the municipality's energy consultant can negotiate contract terms that simply aren't available to individual consumers. Typical aggregation contracts include fixed rates, no auto-renewal penalties, renewable energy options, and clear disclosure of all cost components.

Historical Savings Performance

Illinois aggregation programs have a mixed but generally positive track record on savings. When contracts were negotiated during low-price periods (typically 2019–2020 and 2022–2023 shoulder seasons), municipalities locked in rates well below the utility's Price to Compare for extended periods. Programs negotiated during high-price periods (2021–2022 peak, winter 2022–2023) delivered less consistent savings.

A 2023 study by the Illinois Commerce Commission found that active aggregation programs saved participating residents an average of $85–$140 per year compared to utility default supply over the prior five-year period — meaningful savings delivered passively to residents who did nothing after enrollment.

Green Energy Options

Many Illinois municipalities are using their aggregation contracts to advance community sustainability goals. Several programs now specify 50–100% renewable energy content for the aggregation supply — often at a modest premium of $1–$3/month that residents find acceptable. This gives communities access to green supply options they might not pursue individually.

Is Your Illinois Town Part of a Community Aggregation Program? Find Out Now

Hundreds of Illinois municipalities across both ComEd and Ameren territories have established aggregation programs. Here's how to find out if yours is one of them — and what to look for.

How to Check for Your Municipality's Program

  1. Check your utility bill: If your municipality has an active aggregation program and you're enrolled, your bill will show the aggregation supplier's name (not ComEd or Ameren) in the supply section.
  2. Contact village/city hall: Your municipality's utility office or village administrator can confirm whether an aggregation program is active and when it was established.
  3. Check the ICC aggregation registry: The Illinois Commerce Commission maintains records of registered municipal aggregation programs.
  4. Review prior mail: Opt-out enrollment notices are typically sent by first-class mail. If you received but discarded a notice recently, you may already be enrolled.

Questions to Ask About Your Program

If your municipality has an active aggregation program, ask these questions to assess its value:

  • What is the current contracted supply rate per kWh?
  • What is ComEd/Ameren's current Price to Compare?
  • When does the current aggregation contract expire?
  • Is the contracted rate fixed or variable?
  • What renewable energy content is included?
  • Is the aggregation supplier ICC-licensed with a clean complaint record?

If the aggregation rate is above the current utility PTC, you may want to opt out and arrange your own supplier contract at a more competitive rate. For guidance on individual supplier options, see How to Switch Electricity Providers in Illinois.

How to Opt In or Opt Out of Illinois Municipal Aggregation (And What Happens If You Do Nothing)

The opt-in/opt-out mechanics are the most critical operational aspect of Illinois aggregation programs. Getting this right protects your freedom to choose the supply arrangement that best serves your needs.

If Your Municipality Has an Opt-Out Program

If you do nothing: You're automatically enrolled at the municipality's negotiated rate. Your power continues uninterrupted. You'll see the new supplier's name on your next bill. This is the default outcome for the majority of eligible residents.

If you want to opt out: During the enrollment period, complete the opt-out process specified in your notification letter — typically an online form, phone call, or written notice to the supplier. You can also opt out after enrollment is complete, though timing may affect your next billing cycle. Opting out is always available and carries no penalty.

When to opt out: If you already have an individual ARES contract (especially one with better terms), if you have existing solar or net metering arrangements that need special billing setup, or if the aggregation rate is demonstrably higher than available alternatives.

If Your Municipality Has an Opt-In Program

Opt-in programs require you to actively enroll. Watch for enrollment notices from your municipality, check your municipality's website for enrollment instructions, or contact village hall directly. The enrollment window is typically limited to 30–60 days, and late enrollment may not be possible until the next contract cycle.

After Opting Out: Your Options

If you opt out of municipal aggregation (or your municipality doesn't have a program), you're responsible for your own supply arrangement. Your options:

  • Utility default supply (PTC): Return to or remain on ComEd/Ameren's standard supply rate — no action required
  • Individual ARES contract: Shop competitive rates through a broker and sign directly with an ARES — typically produces the best results for active buyers
  • Another community aggregation: Some county-level or regional aggregation programs are available beyond the municipal level

Not Sure If Your Illinois Aggregation Rate Is Still Competitive?

Our team will compare your municipality's current aggregation rate against available ARES alternatives and tell you whether you're getting the best deal — or whether opting out and arranging your own supply would save you more.

Compare My Aggregation Rate

Frequently Asked Questions: Illinois Municipal Energy Aggregation

What is municipal energy aggregation in Illinois?

Municipal aggregation allows Illinois cities and villages to negotiate electricity supply contracts on behalf of all eligible residents, using collective purchasing power to secure rates that individual customers couldn't obtain independently.

Is Illinois municipal aggregation opt-in or opt-out?

Illinois municipalities can establish either opt-in or opt-out programs. Opt-out programs (more common) automatically enroll eligible residents unless they actively decline. Opt-in programs require residents to proactively join.

How do I know if my Illinois town has an aggregation program?

Contact your municipality's village hall, check your current utility bill for a non-utility supplier name in the supply section, or search the Illinois Commerce Commission's aggregation registry.

Can I opt out of Illinois municipal aggregation?

Yes, always. Contact your municipality or the aggregation supplier to opt out — there is no penalty, and you can return to utility default supply or arrange your own individual ARES contract.

Does municipal aggregation save money in Illinois?

It can — but it depends on when the contract was negotiated and current market conditions. ICC data shows active aggregation programs have saved participants an average of $85–$140/year compared to utility default supply over the past five years. Individual results vary significantly.

What happens if I do nothing when my Illinois town has an opt-out aggregation program?

You're automatically enrolled at the municipality's negotiated rate. Your power continues uninterrupted, and the only change is that your supply provider switches from utility default to the municipality's contracted ARES.