This page walks through each program, what it actually pays, and a few claims that do not match the underlying statute.
Federal: Residential Clean Energy Credit (Section 25D)
The 30% federal Residential Clean Energy Credit expired for systems placed in service after December 31, 2025, under Public Law 119-21 (the One Big Beautiful Bill). The credit covered solar electric property, battery storage of 3 kWh or more, and associated labor and balance-of-system costs at qualifying U.S. residences. Re-roofing and structural roof work unrelated to mounting did not qualify even while the credit was active. IRS Residential Clean Energy Credit guidance and the IRS FAQ on P.L. 119-21 document the cutoff.
Section 48E (the commercial clean electricity credit) remains in effect for third-party-owned systems. In a lease or power purchase agreement, the leasing company owns the system and claims the 48E credit; the homeowner does not. Summit’s detailed explanation lives on the page on the 2026 federal credit.
State: Illinois Shines
Illinois compensates residential solar systems through Illinois Shines , administered by Illinois Power Agency. The program structure varies by state, but the practical question for a Grayslake homeowner is the same: how much of the system price does the state program offset, and is the value delivered up front or over time?
A homeowner should ask any installer to break out the Illinois Shines value as a line item on the proposal so the math is visible, not bundled into the headline net price. Current values and contract terms are documented on the Illinois Power Agency site linked above, and the Illinois Shines value is one of the inputs that determines the post-incentive net on the Grayslake cost page.
Utility / state rebate: Smart Inverter Rebate (ComEd) / Distributed Generation Rebate (Ameren)
Smart Inverter Rebate (ComEd) / Distributed Generation Rebate (Ameren) delivers an additional up-front benefit to qualifying residential systems in Illinois: $300/kW, approximately $2,100 for a typical 7 kW residential system. Eligibility rules and rebate amounts move with the utility's tariff cycle or the program year, so the figure on any installer's proposal should be verified against the current Illinois Shines Approved Vendor list before treating it as a fixed input.
City and county: Lake County
DSIRE, the federally funded clearinghouse for state and local energy incentives, lists city-level solar incentives where they exist. For most Illinois municipalities, including Grayslake, the state and utility programs are the full incentive stack; there is no city-specific rebate or income-tax credit layered on top. Verify the current state of any local incentive at DSIRE’s Illinois page before signing.
State-specific compliance note
ComEd transitioned to Smart Solar Billing on January 1, 2025. Pre-2025 systems remain grandfathered to retail-rate net metering. New installs receive supply-rate-only credit on exports, currently 9.66¢/kWh through May 2026.
What does not exist in Illinois
- A 25% state income-tax credit for residential solar. It is not on the IL-1040, not in the Illinois Department of Revenue’s schedule of credits, and not listed on DSIRE. Marketing copy that cites a 25% state credit is conflating multiple incentives or borrowing the figure from another state. Summit covers the conflation in detail on the 25% state credit myth page.
- A blanket residential sales-tax exemption for solar equipment. Illinois treats solar equipment differently than property tax, and there is no statewide retail sales-tax exemption specifically for residential solar materials. Quotes that bake an implied sales-tax exemption into the math should be re-checked.
Property tax: assessment exemption
Illinois exempts a solar energy system from increasing the assessed value of a residential property under 35 ILCS 200/10-605. The installed system itself does not raise the property tax assessment, which is a real benefit even though it does not appear as a line item on any tax form. The exemption is administered by the local assessor; a homeowner may need to file the relevant exemption certificate with the Lake County assessor’s office to claim it formally.
Verifying these numbers
Every figure on this page traces to a primary source: IRS guidance for the federal credit, the Illinois Shines public documents for the state-incentive value, Illinois Commerce Commission tariff filings for Commonwealth Edison program terms, and DSIRE for any local additions. Summit’s methodology page lists the verification process and the dates each input was last checked.