Supply-only net metering changed the math for new solar customers in Illinois. Here's what it means for system size and batteries.
What changed on January 1, 2025
Before 2025, Illinois solar customers received full retail-rate credit for excess energy sent to the grid. Customers who interconnect on or after January 1, 2025 receive supply-only net metering: exported energy earns credits against the supply portion of your bill, but not delivery charges.
Customers who interconnected by December 31, 2024 keep full retail-rate net metering for the life of their system, up to 30 years.
Credits that roll forward
For customers interconnected on or after January 1, 2025, net metering credits carry forward and don't expire at the end of an annual period. That helps Illinois homeowners bank summer production for winter months.
What it means for your system
Because energy you use directly is worth more than energy you export, right-sizing matters. Oversizing a system to export lots of power is less valuable than it used to be. Batteries — which also qualify for a $300/kWh utility rebate — help you use more of your own solar in the evening.
- Size from your actual 12-month usage
- Consider future loads like an EV or heat pump
- Evaluate a battery for self-consumption and backup
