What changed in 2025
Before 2025, Illinois offered full retail net metering: every kilowatt-hour you sent to the grid offset one you bought later, including the delivery part of your bill.
For systems that started operating on or after January 1, 2025, exported power is credited against the supply portion of your bill only, which is roughly the "Price to Compare" ComEd and Ameren publish. Delivery charges, taxes and fixed fees still apply.
Power you use directly in your home while the sun is shining isn't affected. It never touches the meter, so it saves you the full retail rate.
The trade-off: the distributed generation rebate
In exchange for the change, ComEd and Ameren pay new solar customers a one-time rebate of about $300 per kW of system size (with a smart inverter). On a 7 kW system that's about $2,100 back, usually through your installer.
Do my credits expire?
Bill credits roll forward month to month. Ask your installer how your utility handles credits at the end of the annual period, since the rules have shifted and can differ between ComEd and Ameren.
How to size a system under the new rules
- Start from your last 12 months of usage, not just one bill.
- Favor production you'll use during the day, like air conditioning, a pool pump, an EV charged at home or someone working from home.
- Consider a battery if you're on, or willing to join, a time-of-use rate. The storage rebate requires one.
- Ask installers to show savings with supply-only export credits, not old full-retail assumptions.
Want real numbers for your roof? Get a free Illinois solar quote and a specialist will model it with your actual utility rates.
Sources
This guide is general information, not tax, legal or financial advice. Incentive programs change, so confirm current terms with your installer, your utility and a tax professional.