About 1,265 kWh a year for every kW
The planning estimate for Aurora is roughly 1,265 kWh a year per kW of panels installed. It is derived from satellite irradiance with a standard performance ratio applied rather than measured locally, which makes it a good screening number and a poor contractual one.
On a given house it moves with orientation, pitch, shade and usable area. South-facing planes produce across the whole day while east and west faces concentrate output at one end of it. Pitch affects yield and how quickly snow slides clear. Usable area is what remains once vents, stacks, chimneys and setbacks are subtracted, which is always less than the roof looks from the street.
Ask for production modelled per roof plane rather than as one house total, with the shading assumptions written down. That breakdown is what shows whether the last panels in a design are productive or are there to make the system size look impressive.
Supply-only credit, and what it does to the arithmetic
As of 2025, new residential and small commercial net metering customers in ComEd territory moved from full retail rate net metering to supply-only net metering. Exports are credited against the electricity supply portion of the bill rather than the full retail rate.
Think of your bill as two halves. Supply is the electricity itself. Delivery is the wires that bring it. A kilowatt-hour you use the moment you generate it avoids both. A kilowatt-hour you export now earns credit against the supply half only. That gap is the reason a system sized to your actual consumption is worth more per dollar than one sized to fill the roof.
It also means shifting flexible load into daylight is worth real money here: running the dishwasher, the laundry or an EV charger while the array is producing converts export credit into avoided retail purchase. Ask your installer to confirm the current tariff for your address before the design is fixed, since Illinois net metering terms have been through ongoing Illinois Commerce Commission proceedings and can change again.
If your property is a designated historic one
Aurora's Historic Districts and Landmarks Guidelines require Historic Preservation Commission review of solar panels on a designated historic property. The standard is a visibility standard: panels must sit where they are not visible, or only minimally visible, from the public right-of-way.
That turns the design problem into a geometry problem. A rear-facing plane, a lower roof behind the main mass, or a garage or outbuilding roof can satisfy the standard where the front elevation cannot, and the best solar plane on the house may be the one you are least able to use. Where panels can be fully hidden, staff can approve the work through a Certificate of Appropriateness rather than sending it to the full commission, which is the faster path.
So the first call, if your property is designated, is to the city rather than to an installer. Establish what placement would be approvable before you pay for a design, because a proposal that puts the array on the street-facing plane is not a proposal you can build, however good its production numbers look.
Permits for everyone else
For a property outside the historic designation, the process is ordinary. Installers apply for a Single Family or Commercial Solar Installation Permit through Aurora's Building and Permit Division, and the city has held a Gold-level SolSmart designation since February 2018, a recognition specifically about streamlining local solar review.
A SolSmart designation is a statement about process rather than a promise about your timeline, so it is still worth asking your contractor what recent Aurora jobs have actually taken and what the submission package needs to contain. A contractor who works the city regularly answers from experience.
Confirm as well who files the permit and who books the inspection. Projects stall most often not on a rule but on both parties assuming the other was handling a step.
The money: Illinois Shines, and the credit that ended
Illinois Shines, the state Adjustable Block Program run by the Illinois Power Agency, pays Renewable Energy Credit money to Approved Vendors, who may pass that value to you as reduced equipment or installation cost. It requires using an Approved Vendor, and the amount passed through is the vendor's decision, so ask each one for the Disclosure Form that shows exactly how much of the REC payment reaches you.
Illinois Solar for All is the separate income-based program. It covers homeowners, renters through community solar and multifamily building owners, on terms structured so participating households pay less for electricity than they would have without solar. Eligibility is income-based and worth checking before you shop for quotes rather than after.
The 30 percent federal residential tax credit under Section 25D is not part of this picture any more. It applied through December 31, 2025 and does not cover a purchased home system placed in service after that date, so a 2026 purchase in Aurora cannot claim it. Some material you will find online, including pages published by reputable organisations, has not been updated and still describes it as available. A lease or power purchase agreement provider may claim the separate business credit under Section 48E and reflect part of it in your rate.