Illinois solar leads

Sunlight in Chicago

Chicago, the largest city in Illinois in the Census Bureau’s July 1, 2025 estimates, is the reference point for this page. The PVWatts calculator, which NREL created and the National Laboratory of the Rockies now maintains, puts the average solar radiation on a modeled array in Chicago at 4.57 kWh per square meter per day (checked October 9, 2026).

The run uses PVWatts version 8 defaults: a fixed array on an open rack, 20 degrees from horizontal, pointed due south, at Chicago’s gazetteer point, with typical-year weather from the National Solar Radiation Database. Illinois runs about 390 miles from north to south, so Springfield or Carbondale will read differently from Chicago; the value supports comparisons between states and is not a production estimate for a home.

Illinois Commerce Commission installer certification

Illinois regulates solar installers through its utility commission rather than a contractor board. Under Section 16-128A of the Public Utilities Act and 83 Ill. Adm. Code Part 468, the Illinois Commerce Commission certifies distributed generation installers. The Commission’s page says that after December 31, 2013, with the exception of self-installers, every entity that installs distributed generation facilities must be certified before installing any in Illinois. “Install” is defined there as completing the electrical wiring and connections needed to interconnect the facility with the utility’s distribution system (checked October 9, 2026).

The application instructions require the applicant to certify that only a “qualified person” will perform or directly supervise installations. Under 83 Ill. Adm. Code 468.20, a qualified person has completed at least five installations of the specific distributed generation technology, or has finished one of several listed programs with lab or field work, such as a registered journeyman electrician apprenticeship or a national distributed generation certification. The application fee is $50, and the Commission’s page lists an annual recertification report due by April 1 under 468.80(b) (checked October 9, 2026).

The Commission publishes a list of certified installers on the same page, so a buyer placing Illinois solar requests can check an installer’s certification before routing anything to it. Contractor licensing for other trades is covered on Illinois window replacement leads.

Illinois detached homes and the Cook County effect

Illinois has fewer detached houses than most states, because of Chicago’s apartments and two-flats. In the 2020-2024 table B25024, 3,178,371 of the state’s 5,457,452 housing units are single-family detached, 58.2%, the 11th lowest share of the 50 states. Among owners the share is higher: table B25032 counts 2,660,579 owner-occupied detached homes, 78.7% of the 3,378,910 owner-occupied homes.

Renters live in 1,657,539 of the 5,036,449 occupied homes in Illinois, about 32.9%, in the 2020-2024 table B25003. Outside Cook County, the detached share of owner homes in the county table rises above 76%.

For the age and value of Illinois housing, see Illinois window replacement leads; for heating fuel and degree days, see Illinois HVAC leads.

What the Illinois numbers mean for solar buyers

Read together, the Illinois facts suggest three working points for a buyer planning solar coverage:

• Certification is a routing check. The ICC certified installer list lets a buyer confirm that every installer it serves is certified under Part 468 (checked October 9, 2026).
• Program participation shapes the sale. Installers working inside Illinois Shines or Illinois Solar for All follow those programs’ rules, which the Agency described as current on October 9, 2026, so buyers ask which programs an installer uses.
• Cook County is mixed housing. With 63.7% of owner homes detached in Cook against 84.2% in Will in the 2020-2024 ACS, ZIP code lists inside Cook matter more than the county line.

These points describe Illinois rules, programs, housing and installed solar. They do not state how many leads exist, what they cost or where they come from.

Request Illinois solar leads

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