Supply-only net metering, and why exports are worth less now
As of 2025, new residential and small commercial net-metering customers in Ameren Illinois territory moved from full retail rate net metering to supply-only net metering. The credit now covers the electricity-supply portion of the bill rather than the full retail rate.
Your bill has supply charges and delivery charges. Under the older arrangement an exported kilowatt hour offset both. Under supply-only crediting it offsets the supply component only, so the same exported kilowatt hour is worth less than it used to be, and materially less than a kilowatt hour you consume at the moment you generate it.
Two consequences follow, and they are the most useful things on this page. First, treat any payback figure built on full retail net metering as out of date, including advice from a neighbour who installed a few years ago and is genuinely reporting their own experience. The rules changed for new customers, not for them. Second, sizing should follow your own consumption rather than your roof area, because generation beyond what you use earns the narrower credit.
Ask your installer to confirm the current net metering tariff for your address in writing, and to show how their model values exports against self-consumed generation. If the two are treated the same in the arithmetic, the model is describing the old rules.
Illinois Shines is a separate incentive, and worth asking about specifically
Illinois Shines, the Adjustable Block Program, pays renewable energy credit payments as a separate incentive on top of net metering. It is not a discount on your bill and it is not the same thing as the crediting arrangement above, which is why it needs asking about in its own right.
Because it is separate, the value that actually reaches you depends on how your installer or an approved vendor structures it. Some pass it through as an upfront reduction in the system price, some as a payment over time. Ask which, ask what figure they have assumed, and ask what happens if the programme's terms change before your system is energised.
The honest framing is that Illinois Shines can meaningfully improve a project's economics, and that the number in a quote is a projection rather than a guarantee until it is contracted. A quote that folds an assumed Illinois Shines value into a headline payback figure without separating it out is not giving you enough information to compare against another quote.
Fewer than half of homes here come with a roof
Single-detached houses are 43.2 percent of Champaign's 41,299 housing units, so under half of households have a roof one owner controls. Buildings of 20 or more units are 23.5 percent and buildings of 10 to 19 units another 13.1 percent, which together is more than a third of the stock in substantial apartment buildings.
For those residents the realistic path is not a rooftop array on their own unit. The roof belongs to the building owner or is a common element, so anything that happens there starts as a written proposal to the owner or association covering cost, ownership of the equipment, insurance and roof replacement. In a large building that proposal competes with every other capital priority, so expect a long timeline rather than a quick answer.
If you are a condo owner rather than a renter, the governing document is the declaration and its rules on work affecting common elements, and the decision belongs to the association rather than to you. Read that before you read a quote.
For the 43.2 percent with a detached house, the remaining questions are the roof itself: orientation, shading and the age of the covering. Panels outlast most coverings, so one within a few years of replacement should be replaced before the array goes on.
A strong resource, and the credit that no longer applies
Plan on roughly 1,293 kilowatt hours a year for every kilowatt installed on a well oriented, unshaded array. That is a strong figure and the best among the cities in this group, but it is a screening number derived from irradiance data rather than a measurement from Champaign roofs, so treat it as a ceiling for your address.
A strong resource combined with supply-only export crediting points to the same conclusion from two directions: build to your own consumption. You reach that consumption with fewer panels here than in a weaker location, and the panels beyond it earn the narrower credit, so the cheaper system is also the better-matched one.
The 30 percent federal residential tax credit under Section 25D applied through December 31, 2025 and is not available for a purchased home system placed in service after that date. A purchase in Champaign now cannot claim it, and any quote or calculator that still applies it is overstating the return substantially.
Rebuild the arithmetic from the parts that still exist: the Illinois Shines value actually passed through to you, the supply-only credit for exports, and the electricity you no longer buy. If you go solar through a lease or a power purchase agreement, the provider may claim the business version of the credit under Section 48E and reflect part of it in the rate offered, which is a question for the provider and a tax advisor rather than an assumption for your budget.