Grid & off-grid

Net metering calculator, Illinois

Enter your exact usage, system size, and rate details to see how Illinois's net metering policy affects your solar bill, with precise controls for season, tiered rates, and fixed fees.

Your numbers

1 Project details Optional
Shown on your exported report. Leave blank to skip.
2 Your usage and system
Find this on a recent utility bill, usually labeled kWh used.
Use your quoted or planned system size. Panel count times panel wattage divided by 1,000 gives a rough figure.
Solar production swings seasonally; pick a specific month type to see how your bill shifts.
Most utilities charge a flat customer or connection fee regardless of usage.
3 Your location and rate
Defaulted to Illinois's statewide average. Adjust if you know your local figure.
Defaulted to Illinois's current average residential rate. Your utility's actual rate may differ.
Illinois typically credits exports around 100% of retail. Full retail net metering up to 2 MW under the Illinois Power Agency Act.
Some utilities charge progressively higher per-kWh rates as monthly usage climbs into higher tiers.
Accounts for inverter loss, wiring loss, dust, and temperature derate combined.
Informational only. A monthly cycle means unused export credit does not carry to the next bill; annual and rolling cycles do.

How it works

Three steps to your Illinois solar bill estimate

Step 1

Enter your usage, system size, and season

Pull your monthly kWh from a recent bill and enter your planned or quoted system size in kW. If you only know your panel count, multiply it by each panel's wattage and divide by 1,000 to get a kW figure first. Select a season to model a specific month rather than only an annual average.

Step 2

Confirm your rate, tier, and export credit

Illinois's typical residential rate and export credit level are filled in by default. Swap in your utility's actual tariff numbers, tier bracket, and fixed monthly fee if you have a recent bill or interconnection agreement showing them.

Step 3

Compare the result to a full retail scenario

Run the net billing vs net metering comparison tool to see exactly how much Illinois's current export credit rate costs you compared to full 1:1 retail crediting.

How net metering works in Illinois

CEJA moved new customers to supply-only credit in 2025

Illinois's Climate and Equitable Jobs Act (CEJA) shifted ComEd, Ameren, and MidAmerican customers from full retail net metering to a "supply-only" structure starting January 1, 2025, a transition the Illinois Commerce Commission tracks in detail. Under the old rules, export credits offset your entire bill, supply, delivery, and fixed charges together. Under supply-only crediting, exports only offset the supply portion, which roughly cuts the credit's value in half; ComEd's own example showed the rate dropping from about 13.6 cents/kWh to about 6.5 cents/kWh.

Grandfathering depended on your paperwork timing

Systems fully documented and submitted for interconnection by December 31, 2024 were grandfathered into full retail net metering for 30 years from their permission-to-operate date. If your system missed that filing deadline, even by a small margin, it falls under the newer supply-only terms instead.

Grandfathered status can still be lost later

For ComEd customers specifically, a future modification requiring a new interconnection application, such as a meaningful capacity increase to an existing system, can move an otherwise grandfathered system onto the newer supply-only terms; Illinois's tax credit and rebate estimator is worth reviewing before you make any change that could trigger that. It's worth keeping that in mind before making changes to an older Illinois system.

Why self-consumption matters more under supply-only crediting

With exports now covering only part of your bill instead of all of it, raising your own self-consumption rate holds more relative value than it did under the old program. The grid tie with battery backup comparison tool shows what storing surplus for later use does to the math under this structure.

Interconnection and the off-grid alternative

Whether your system falls under the old or new crediting structure, connecting still requires a standard interconnection review with your utility. And even under supply-only rates, staying grid-tied remains far cheaper than a fully off-grid system; the grid tie vs off grid comparison tool shows how much cheaper.

Questions

Frequently asked

Illinois moved new solar customers to supply-only net metering in 2025 under CEJA, crediting exports at roughly the supply portion of a retail rate that's ranged from about 20 to 24 cents through 2026, close to half of full retail. Systems grandfathered before 2025 keep full retail crediting instead.

The average residential rate in Illinois has been volatile, peaking around 23.9 cents per kWh in spring 2026 before settling closer to 19.9 cents by June, per EIA data. New systems use CEJA's supply-only net metering since 2025; systems grandfathered before the cutoff keep full retail crediting for 30 years.

Starting January 1, 2025, CEJA moved ComEd, Ameren, and MidAmerican customers from full retail net metering to a supply-only structure, where exports offset only the supply portion of your bill rather than the entire bill. ComEd's own example showed this roughly cutting the export credit in half, from about 13.6 cents/kWh to about 6.5 cents/kWh.

Potentially, yes. Systems submitted by December 31, 2024 were grandfathered into full retail net metering for 30 years. For ComEd customers specifically, a later change requiring a new interconnection application, such as a meaningful capacity increase, can move a grandfathered system onto the newer supply-only terms.

Related tools

Compare Illinois's policy to other structures

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