Electricity in Illinois: How It Works, What You’ll Pay & Community Aggregation Explained

How Illinois Electricity Actually Gets to Your Home

Let’s start with the basics: where your electricity comes from and how it gets to you.

Step 1: Generation (Where Power Is Created)

Electricity starts at power plants across Illinois and neighboring states.

Illinois’s generation mix:

• Nuclear: Illinois is the #1 nuclear power state in the U.S. (over 50% of state generation)
• Natural gas: Second-largest source
• Wind: Growing rapidly (especially in central/southern Illinois)
• Coal: Declining but still present
• Solar: Small but increasing

Why nuclear matters: Nuclear provides consistent, 24/7 baseload power. This is why Illinois electricity is relatively stable compared to states relying heavily on fossil fuels.

Step 2: Transmission (Long-Distance Power Lines)

Once generated, electricity travels across high-voltage transmission lines that move power over long distances.

These lines are part of regional systems that balance supply and demand across multiple states. Illinois participates in PJM Interconnection and MISO (Midcontinent Independent System Operator), which coordinate power flow across the Midwest.

You never see or interact with this layer—it’s all behind the scenes.

Step 3: Distribution (Local Delivery)

Electricity enters local distribution networks—the power lines, poles, and transformers in your neighborhood—that deliver electricity directly to your home.

This is where your utility comes in.

The Key Point:

Generation, transmission, and distribution are separate systems managed by different organizations.

This is why multiple companies are involved in getting electricity to your home—and why your bill has charges from more than one source.

Is Illinois a Deregulated Electricity State?

Yes—but with a unique twist: community aggregation. Your city or county can negotiate electricity rates on behalf of all residents, then automatically enroll you in that program. You might already have a competitive supplier without realizing it.

Here’s the basic structure: Illinois deregulated electricity in the late 1990s, allowing residents to choose who supplies their electricity (generation) while ComEd or Ameren continues to deliver power (transmission/distribution).

But unlike other states, you don’t have to actively shop.

Many Illinois municipalities participate in community aggregation programs:

1. Your city/county negotiates a group rate with a licensed supplier
2. All residents are automatically enrolled (unless you opt out)
3. You receive a notice explaining the program and your rate
4. If you do nothing, you stay enrolled
5. You can opt out anytime and return to utility default service

This means most Illinois residents fall into one of three categories:

• Enrolled in community aggregation (automatic, often good rates)
• Shopping independently with a competitive supplier (active choice)
• On utility default service (no supplier chosen, no aggregation)

Community aggregation is unique to Illinois among major deregulated states. It’s designed to give residents collective buying power without requiring individual research.

For a detailed explanation of how electricity deregulation works across the U.S., see our guide: Regulated vs Deregulated Electricity Markets.

Compare Illinois to other deregulated states: Texas, Pennsylvania, Ohio, or view all states.

Utilities vs. Suppliers in Illinois: Who Does What

This is where people get confused. Let’s clear it up.

Utilities (Who Delivers Your Power)

The two major Illinois utilities:

1. ComEd (Commonwealth Edison)

• Service area: Northern Illinois (Chicago and suburbs, Rockford, parts of north-central IL)
• Customers: ~4 million
• Website: comed.com

2. Ameren Illinois

• Service area: Central and southern Illinois (Springfield, Champaign, Peoria, Bloomington, parts of Metro East)
• Customers: ~1.2 million
• Website: ameren.com/illinois

What utilities do:

• Own and maintain power lines, poles, transformers, meters
• Deliver electricity to your home
• Respond to outages and emergencies
• Send your monthly bill

What utilities DON’T do:

• Compete with other companies (they’re regulated monopolies)
• Set competitive supply rates (that’s for suppliers)

Your utility is determined by where you live. You can’t change it.

Electricity Suppliers (Who You CAN Choose)

What they do:

• Generate or buy electricity wholesale
• Sell it to you at retail rates
• Offer different pricing plans (fixed-rate, variable-rate, renewable)

What they DON’T do:

• Deliver electricity (that’s the utility)
• Respond to outages (call your utility, not your supplier)
• Own infrastructure

Examples: Direct Energy, Constellation Energy, IGS Energy, Verde Energy, and dozens of others.

How They Work Together

Your monthly bill includes:

1. Supply charges (from your chosen supplier OR your utility’s default rate)
2. Delivery charges (from your utility—always the same)

Example:

• Supply: 1,000 kWh × 7¢/kWh = $70
• Delivery: 1,000 kWh × 4¢/kWh + fees = $50
• Total: $120

Key point: Even if you switch suppliers and lower your supply charges, your delivery charges stay exactly the same.

What You’ll Actually Pay for Electricity in Illinois

Let’s talk real numbers.

Illinois Electricity Rates — March 2026

Understanding your bill requires separating two different numbers: the supply rate (what you pay for the electricity itself, which you can shop) and the all-in rate (supply + delivery, which is what actually appears on your bill).

Supply rates — what you shop against:

Sources: PlugIn Illinois (plugin.illinois.gov), Citizens Utility Board (citizensutilityboard.org), January 2026

All-in average rate (supply + delivery):

• Illinois residential average: ~16.96¢/kWh (March 2026, EIA / EnergySage)
• U.S. national average: ~16.77¢/kWh
• Average monthly bill: ~$115/month at ~800 kWh usage

The number that matters if you want to save money is the supply rate — specifically the Price to Compare. Delivery charges are set by your utility and can’t be changed regardless of which supplier you choose. If a supplier offers you a rate below ComEd’s 9.6¢ or Ameren’s 8.769¢, you save money on supply. If they offer you more, you’re paying a premium.

The official place to compare current supplier offers against the Price to Compare is PlugIn Illinois — the state-run comparison tool managed by the Illinois Commerce Commission. It lists all licensed Alternative Retail Electric Suppliers (ARES) and their current rates by zip code.

Why Illinois Rates Are Moderate

1. Nuclear dominance: Illinois gets over 50% of its electricity from nuclear power, which provides stable, low-cost baseload power.

2. Natural gas availability: Illinois has access to cheap natural gas from shale formations (Marcellus, Utica).

3. Milder climate: Illinois summers aren’t as brutal as Texas or Arizona (less AC demand).

4. Competition: Deregulation and community aggregation create downward pressure on supply rates.

Why Bills Vary Between Households

Even though the average is $110–$150/month, your bill could be way higher or lower. Here’s why:

1. Electricity Usage (Biggest Factor)

What drives usage:

• Air conditioning in summer (Illinois gets hot and humid in July/August)
• Electric heating or space heaters in winter (though most use natural gas)
• Home size (bigger homes = more power)
• Appliance efficiency (old appliances use more)
• Number of occupants

Example:

• 600 kWh/month apartment: ~$96/month
• 1,200 kWh/month single-family home: ~$192/month

2. Supply Plan Structure

Fixed-rate plan at 7¢/kWh:

• Stable, predictable

Variable-rate plan:

• Could be 5.5¢/kWh in spring (cheap)
• Could be 10¢/kWh in July (expensive)

Community aggregation rate:

• Often middle-of-the-road (better than utility default, but not the cheapest available)

3. Delivery Costs

Delivery charges are the same for everyone in your utility’s service area, regardless of supplier.

What delivery covers:

• Infrastructure maintenance
• Meter reading
• Grid reliability
• Emergency response

Typical delivery costs: ~3–5¢/kWh + monthly fees

You can’t avoid or reduce delivery charges by switching suppliers.

4. Seasonal Demand

Summer (June–August):

• Higher usage (air conditioning)
• Higher wholesale prices (peak demand)

Winter (December–February):

• Moderate usage (electric heating is less common in Illinois)
• Variable wholesale prices (cold snaps can spike demand)

Spring/Fall:

Lowest usage and bills

Why Electricity Prices Change in Illinois

Several factors contribute to electricity price fluctuations in Illinois, many of which are not immediately visible on a monthly bill.

Wholesale electricity markets play a major role. Illinois participates in regional markets that coordinate electricity supply across multiple states. When demand increases — such as during extreme heat or cold — wholesale prices can rise.

Seasonal usage patterns also matter. Summer air-conditioning demand and winter electricity use both influence overall costs, even when electricity is not the primary heating source.

Plan structure adds another layer. Fixed-rate plans lock in a price for a set period, while variable-rate plans can change from month to month. Promotional pricing, minimum usage requirements, and contract expirations can all affect what customers ultimately pay.

Community Aggregation in Illinois: Why You Might Already Have a Supplier

This is UNIQUE to Illinois and catches a lot of people off guard.

What is community aggregation?

Simple explanation: Your city or county can negotiate an electricity supply contract on behalf of all residents. Then, you’re automatically enrolled unless you opt out.

The goal: Use collective buying power to get lower rates than individuals could negotiate on their own.

How it works:

1. Your municipality passes an ordinance allowing aggregation
2. They negotiate a contract with a competitive supplier
3. You’re automatically switched to that supplier (unless you opt out)
4. You get a notice in the mail explaining the program
5. If you do nothing, you stay enrolled

Key point: You don’t have to actively choose a supplier. The municipality does it for you.

Why this confuses people:

Scenario: You never “chose” a supplier, but your bill shows charges from a company that’s not ComEd or Ameren.

What probably happened: Your community enrolled you in an aggregation program.

How to check:

• Look at your bill—if the supply charges are from a company other than your utility, you’re likely in aggregation
• Call your municipality and ask if they have a community aggregation program
• Check your mail for opt-out notices (they’re required by law)

Pros and cons of community aggregation:

Pros:

• Often secures lower rates than utility default
• No effort required (automatic enrollment)
• You can opt out anytime

Cons:

• Can be confusing if you don’t know you’re enrolled
• Rates may change when the contract expires
• You might get a better deal shopping on your own

Bottom line: Community aggregation isn’t bad—it’s just something you need to be aware of.

Why Electricity Prices Change in Illinois

Bills can fluctuate even when your usage stays the same. Here’s why:

1. Wholesale Market Conditions

Illinois participates in PJM Interconnection and MISO, regional markets that coordinate electricity across multiple states.

What affects wholesale prices:

• Natural gas prices (Illinois uses a lot of gas-fired generation)
• Extreme weather (heat waves, polar vortexes)
• Grid capacity constraints

When wholesale prices rise, retail prices eventually follow (especially for variable-rate plans).

2. Plan Structure

Fixed-rate plans:

• Your rate stays the same for the contract term (6, 12, or 24 months)
• Protected from market spikes

Variable-rate plans:

• Your rate changes month-to-month based on market conditions
• Can spike unexpectedly

Community aggregation:

• Rate is fixed for the contract term (usually 1-2 years)
• When the contract expires, the rate can change significantly

3. Contract Expirations

Common scenario:

You’re on a 12-month fixed-rate plan at 7¢/kWh.

Month 13: The contract expires and you’re automatically moved to a variable rate.

New rate: 11¢/kWh (market conditions changed).

Result: Your bill jumps even though usage stayed the same.

Lesson: Always monitor contract renewal dates.

4. Infrastructure Costs and Regulatory Fees

Delivery charges can increase over time due to:

• Grid modernization projects
• Storm damage repairs
• State and federal mandates

These charges are regulated and apply to everyone in your utility area.

Should You Choose an Electricity Supplier in Illinois?

Honest answer: It depends on your situation.

You might benefit from shopping if:

• You’re not in a community aggregation program (or want to opt out)

• You want a fixed-rate plan for price stability

• You’re comfortable comparing offers and monitoring contracts

Current supplier rates are noticeably lower than your utility default

You might be fine staying put if:

• You’re in a good community aggregation program

• You prefer minimal decision-making

• You move frequently

• You don’t want to deal with contracts

Key insight: Community aggregation often provides decent rates without any effort. Shopping independently might save you a bit more, but it’s not always worth the hassle.

How to Check If You’re in Community Aggregation

Step 1: Look at your bill

• Check the “supplier” or “supply charges” section
• If it’s NOT ComEd or Ameren, you’re probably in aggregation

Step 2: Check with your municipality

• Call your city/village/county offices
• Ask: “Does our municipality have a community aggregation program?”

Step 3: Review past mail

• Look for opt-out notices (they’re required by law)
• Usually come before enrollment or when contracts renew

Step 4: Visit your utility’s website

• ComEd and Ameren have tools to check your current supplier

Understanding Your Illinois Electricity Bill

Your bill has multiple sections. Here’s what they mean:

Supply Charges

• The cost of generating electricity
• Changes based on your supplier (utility default, community aggregation, or competitive supplier)

Delivery Charges

• The cost of delivering electricity to your home
• Set by your utility (ComEd or Ameren)
• Same regardless of supplier

Taxes and Fees

• State and local taxes
• Regulatory fees
• Infrastructure investment charges

Why bills change even when usage doesn’t:

• Supply rates can fluctuate (variable plans, contract expirations)
• Delivery charges can increase (infrastructure investments)
• Fees and taxes can change

Understanding this breakdown helps you identify what’s driving cost changes.

Common Questions About Illinois Electricity

What if my community aggregation contract expires?

When the contract ends, you might:

• Be automatically re-enrolled in a new contract (at a potentially different rate)
• Be returned to utility default supply
• Receive a notice with opt-out instructions

Watch your mail and monitor your bill around contract expiration dates.

Can I opt out of community aggregation?

Yes. You can opt out at any time and either:

• Return to utility default supply
• Choose your own competitive supplier

No penalty for opting out.

What happens if my supplier goes out of business?

You’re automatically returned to utility default supply. Your power stays on. The Illinois Commerce Commission oversees this transition.

Can I switch suppliers if I’m renting?

Usually yes, as long as the electric account is in your name. Check with your landlord if unsure.

Do I need to notify my utility if I switch suppliers?

No. The supplier handles that. Your utility processes the switch automatically.

How Illinois Compares to Other States

Illinois vs. Other States:

• Lower rates than: Michigan, Wisconsin
• Similar to: Ohio, Indiana
• Higher than: Iowa, Missouri (but not by much)

What makes Illinois unique:

Unlike Texas, Pennsylvania, or Ohio, Illinois is the only major deregulated state with widespread community aggregation. This means most Illinois residents already have a competitive supplier without having shopped for one — they were automatically enrolled by their municipality.

Unlike Texas, which operates on an isolated grid (ERCOT), Illinois participates in two regional grids: PJM Interconnection (northern IL) and MISO (central/southern IL). This affects wholesale pricing but not your ability to choose suppliers.

Illinois also benefits from nuclear power dominance (50%+ of generation), which keeps rates more stable than states relying heavily on natural gas or coal.

Illinois keeps utility default service available (Texas often requires you to choose a provider), and has fewer extreme temperature swings than Texas (less seasonal bill variation).

Want to compare? Check out our guides on Texas electricity, Ohio electricity, and Pennsylvania electricity.

Resources for Illinois Electricity

Official Tools:

Illinois Commerce Commission (ICC)

• Website: icc.illinois.gov
• Consumer hotline: 1-800-524-0795
• Supplier licensing, complaints, consumer guides

Plug In Illinois (State comparison tool)

• Website: pluginillinois.org
• Compare certified suppliers
• See community aggregation programs

ComEd & Ameren Websites

• Check your current supplier
• View bill details
• Report outages

The Bottom Line: Understanding Illinois Electricity

Here’s what you should take away:

1. Illinois has retail choice (you can choose suppliers), but delivery is regulated (you can’t change utilities).
2. Community aggregation is unique to Illinois. You might already have a supplier without realizing it.
3. Switching suppliers is optional. Utility default and community aggregation are both valid choices.
4. Illinois rates are moderate—right around the national average, thanks to nuclear power and natural gas.
5. Monitor contract expirations. Rates can jump when fixed-rate contracts expire.

Bottom line: Understanding how the system works—especially community aggregation—helps you make better decisions and avoid bill surprises.

Education first. Comparison second. Decisions third.

Data Sources

This guide uses data from:

• Illinois Commerce Commission (ICC)
• U.S. Energy Information Administration (EIA)
• PJM Interconnection / MISO
• ComEd and Ameren Illinois

All statistics reflect recent averages. Your actual costs may vary based on location, usage, and plan choice.