Illinois ended retail net metering. The rooftop math changed.

I.What net metering did, and what replaced it

Net metering treated your meter like a bank. Over a billing month, the grid netted what your system exported against what you imported, and you paid only for the difference. Because the credit ran at the full retail rate, it canceled both the energy itself and the delivery charges ComEd adds to move power across its wires. That is the generous part, and it is the part that ended for new customers.

Under the new structure, exports from a new system are credited closer to the supply-only portion of the rate, the cost of the electricity alone, without the delivery piece. The delivery charges, which make up a large share of a Chicago bill, no longer get erased by the power you send back. In round terms, an exported kilowatt-hour is now worth noticeably less than one you use on-site, which is why installers push you to consume your own power as you make it.

II.The rebate meant to fill the gap

To soften the shift, Illinois pairs the smaller ongoing credit with a one-time distributed generation rebate, paid by the utility when you install a smart inverter, the device that lets a solar system talk to the grid and ride through small disturbances. The rebate scales with system size. At last public report it runs on the order of a few hundred dollars per kilowatt for residential systems in ComEd territory, and more per kilowatt for larger nonresidential projects and for paired storage, per ComEd's filed rate schedules.

Think of it as a trade. You give up years of richer monthly credits in exchange for cash up front that lowers the installed price today. Whether that pencils out depends on how much of your own generation you use, how your installer sizes the array, and how delivery rates move over the life of the system, which is a long bet in a state still rewriting its energy rules.

III.The honest math on a Chicago flat roof

Chicago's building stock tilts the math. Much of the commercial and multifamily core sits under flat roofs, which take panels at a shallow tilt and can host a larger array than a pitched suburban roof. A bigger array exports more at midday, exactly the power now credited at the lower rate, so the gap between self-use and export matters more here than in a bungalow belt where a small system covers most of what the house draws.

Winter sharpens it further. Lake-effect cloud and short December days cut production when heating load climbs, so a system sized to summer export can underdeliver in the months you lean on it, and the export credit will not rescue a January bill. The practical move, installers say, is to size closer to your own daytime use, add storage only if the numbers justify it, and treat the rebate as the real near-term return rather than the monthly credit.

IV.Worth watching this month

1. Illinois Commerce Commission docket pages carry the exact transition date and tariff language for ComEd's net metering change, worth reading before you sign a contract.

2. ComEd's filed rate schedules list the current distributed generation rebate values per kilowatt, which can be revised, so confirm the figure in effect on your install date.

3. Separately, Illinois Shines, run by the Illinois Power Agency, offers an adjustable block incentive from a different pot of money than the utility rebate, with application windows that open and close through the year.

4. Watch for any ICC proceeding that reopens the export credit rate, since the supply-only basis can shift with ComEd's supply costs from year to year.

5. If you are weighing storage, check whether the paired-storage rebate adder is still funded, because program budgets for these incentives are set in advance and can run dry.