Who has a stake in the roof
Single-detached houses are 25.6 percent of Chicago's housing stock. That is the segment where one owner can authorize a rooftop array outright, and it is a minority of the city. Everything else involves at least one more signature.
Two-unit buildings hold 13.1 percent of units and three and four unit buildings a further 14.4 percent. In a two-flat or a three-flat, roof rights typically involve more than one owner, and there is a second question behind the first: an array feeds one electrical service, so it reduces one unit's bill rather than splitting across the building. Both questions are cheaper to settle before a contract than after one.
Buildings of 20 or more units hold 27 percent of the stock. There, condominium association approval is required before a unit owner can install rooftop solar, and the city has built that requirement into its own paperwork: the Express Permit Program asks for a signed condominium association approval letter describing the work, signed by an officer or property manager. Single-attached row houses are another 3.5 percent, where the roof plane and the property line both need establishing on site.
The Express Permit Program and who has to sign the drawings
Chicago's Express Permit Program covers rooftop photovoltaic systems up to 13.44 kW of inverter output. For a typical house that ceiling is generous, so most residential projects can use the express route rather than a full review.
What the program requires is a specific set of credentialed people. A new installation needs drawings from an Illinois-licensed architect or structural engineer, a licensed general contractor, a licensed electrical contractor, and an ICC Distributed Generation Installer Certification. That is four separate qualifications, and a company quoting you should be able to say immediately which of them it holds in-house and which it subcontracts.
Ask that question early. It is the fastest way to tell a company that installs in Chicago regularly from one that will discover the requirements after taking a deposit. Ask as well who prepares and submits the application, since the drawings have to come from a licensed professional rather than from a sales tool.
What ComEd credits you for exported power
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. The credit now covers the electricity supply portion of the bill rather than the full retail rate.
That distinction is the most important one on this page for anyone comparing quotes. 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, so the same exported kilowatt-hour is worth less than it used to be, and materially less than a kilowatt-hour you consume as you generate it.
Two practical consequences follow. First, treat any payback figure built on full retail net metering as out of date, including advice from neighbours who installed a few years ago. 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 the model treats exports.
Illinois Shines, and the disclosure form to ask for
Illinois Shines, the Adjustable Block Program, is administered by the Illinois Power Agency and sits on top of net metering rather than replacing it. Under its Distributed Generation track, Approved Vendors receive Renewable Energy Credit payments from utilities and may pass that value on to you as reduced equipment or installation cost. Participation requires using an Approved Vendor.
Because the value reaches you indirectly, the amount passed through is a commercial decision rather than a published rate. Ask every vendor for their Disclosure Form, which shows exactly how much of the REC payment they are passing on. Comparing two quotes without those forms means comparing prices without knowing how much of a public subsidy each company kept.
Illinois Solar for All is a separate, income-based program. It serves homeowners, renters through community solar, and multifamily building owners, on terms designed so that participating households pay less for electricity than they would have without solar. Given how much of Chicago's stock is rented or in association-controlled buildings, this is the program worth checking first for a lot of readers here.
What a Chicago roof makes in a year
The planning figure is about 1,233 kWh a year for every kW installed, derived from satellite irradiance data with a standard performance ratio applied rather than measured on local roofs. It tells you whether to pursue quotes; the site survey tells you what to sign.
Flat roofs are common across much of the city's housing, and they change the design conversation. Panels on a flat roof are usually mounted on a tilted or ballasted frame, which raises questions a pitched roof does not: what the structure can carry, how the array is secured against wind, how water still drains and how the roof membrane is penetrated or not penetrated. Those are structural engineering questions, which is part of why the city asks for engineered drawings.
Shading in dense neighbourhoods is the other local factor. A three-flat next door casts a longer shadow in December than in June, and an annual production estimate that ignores the winter sun angle will overstate what you get. Ask for production modelled per roof plane with the shading assumptions stated.
The federal credit is not part of a 2026 purchase
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 2026 purchase in Chicago cannot claim it, and any quote or calculator that still applies it is overstating the return substantially.
The business version of the credit under Section 48E is a separate provision. A lease or power purchase agreement provider may claim it and reflect part of the value in the rate they offer you, which is a question to put to the provider and then to a tax advisor rather than an assumption to carry into your own budget.
The practical instruction is to 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 a salesperson resists doing that, the resistance is itself informative.