Solar Calculator for Illinois: Costs, Incentives & ROI
Illinois combines a supportive solar policy framework with a significant transition underway in how the state compensates residential solar generation. The state's two primary investor-owned utilities — ComEd, an Exelon subsidiary serving the Chicago metropolitan area and the northern half of the state, and Ameren Illinois, serving downstate communities including Springfield, Peoria, and Champaign — both offered net metering at the full retail rate under the original Illinois net metering law. Beginning in 2024 and 2025, the Illinois Commerce Commission's Smart Solar Billing Program introduced a new framework under Docket 24-0205, transitioning newly interconnected systems to an export credit schedule rather than full retail-rate net metering. Customers who interconnected under the prior net metering rules are grandfathered at the retail rate for the remainder of their legacy contract term, making the timing of a new installation material to the long-term economics of a Chicago or downstate Illinois solar system. Illinois residential electricity rates average approximately thirteen to fifteen cents per kilowatt-hour, below the Northeast and California markets but meaningful enough — and rising — to support attractive solar payback periods, particularly for ComEd customers in the Chicago metro where rate schedules include tiered pricing structures that can push effective rates modestly higher for above-average consumers. The federal Investment Tax Credit of thirty percent is the primary national incentive, complemented by Illinois's Special Assessment for Solar Energy Systems under 35 ILCS 200/10-5, which caps the assessed value of a solar installation at its installed cost rather than adding a market-premium increment to property tax liability.
Incentive data updated: May 2026(may be outdated)
Average Solar Cost in Illinois
Average installed solar costs in Illinois typically range from $2.80 to $3.20 per watt before incentives, reflecting the Midwest labor market — with ComEd territory Chicago-area projects carrying modestly higher electrician costs than rural Ameren Illinois service areas. A standard six-kilowatt residential system costs approximately $17,000 to $19,500 before the federal Investment Tax Credit, near the national average and consistent with Midwest regional pricing from LBNL Tracking the Sun. The thirty-percent federal ITC reduces the net installed cost to roughly $11,900 to $13,650 for a six-kilowatt system. Illinois does not offer a statewide solar rebate program comparable to Connecticut's Smart-E Loan or New Jersey's SuSI incentive, but ComEd's rebate programs have periodically offered per-watt incentives for qualifying installations — homeowners should verify current program availability with ComEd or an IDFPR-licensed installer before contracting, as program funding and terms change. Illinois's Special Assessment for Solar Energy Systems under 35 ILCS 200/10-5 limits the assessed value of a solar installation to the system's installed cost, preventing the common scenario in some states where a solar installation adds assessed value equal to the full market premium it adds to the home. Over a twenty-five-year system lifespan, this protection can represent meaningful property tax savings depending on the municipality's property tax rate. Homeowners in competitive Illinois markets — Chicago's northwest and west suburbs, Naperville, and the I-88 corridor — benefit from multiple NABCEP-certified installer options and active quote competition, which tends to keep installed prices near the Midwest average.
- Avg. installed cost
- $3.00/W
- Typical 6 kW system
- $17,000–$19,500
Top Solar Incentives in Illinois
Live incentive data not currently available for Illinois. See the federal incentive guidance via our Solar Tax Credit Calculator.
Electricity Rates in Illinois
Illinois residential electricity rates average approximately thirteen to fifteen cents per kilowatt-hour on a blended basis including supply, distribution, and transmission charges, positioning the state in the middle tier of US electricity markets — well below Connecticut, Massachusetts, or Hawaii, but above the lowest-cost Southeast and Mountain West states. ComEd customers in the Chicago metro area typically pay rates in the thirteen-to-fifteen-cent range, with the supply component subject to competitive retail electricity market dynamics under Illinois's deregulated electricity structure — residential customers may choose an alternative retail electric supplier or remain on ComEd's default supply service, which is priced through a competitive procurement process. Ameren Illinois customers in the downstate territory pay similar blended rates, reflecting a different generation mix and distribution infrastructure. Illinois electricity rates are affected by the state's Renewable Portfolio Standard, transmission infrastructure investments, and the Midcontinent Independent System Operator pricing for the regional wholesale market. While Illinois rates are not in the top tier nationally, they have trended upward over the past decade, and the economics of solar improve meaningfully if rates continue to rise — a six-kilowatt system producing seven thousand kilowatt-hours annually avoids purchasing at whatever the prevailing retail rate is over a twenty-five-year period, providing a natural hedge against rate escalation. The Smart Solar Billing Program's export credit schedule — rather than full retail-rate net metering for new systems — changes the calculation for Illinois homeowners who have above-average solar production relative to consumption, since excess generation earns a credit below the retail rate under the new framework.
Peak Sun Hours in Illinois
Illinois's solar resource is moderate by national standards, with the Chicago metro and northern Illinois receiving approximately four to five peak sun hours per day on a south-facing tilted surface, and the southern tip of the state near Carbondale receiving slightly more — approximately five to five and a half peak sun hours per day — due to its lower latitude. Chicago's latitude of approximately forty-two degrees north produces solar conditions comparable to New England shoreline states and significantly below the Sun Belt. The flat terrain of the Illinois prairie is generally favorable for solar with minimal shading outside urban and forested areas; Chicago's rooftop market deals with more urban tree canopy than rural Ameren Illinois service territory. A six-kilowatt system in Chicago typically produces approximately six thousand five hundred to seven thousand two hundred kilowatt-hours per year, while a comparable system in Springfield or Carbondale may produce seven thousand to seven thousand eight hundred kilowatt-hours per year. Illinois winters benefit panel efficiency slightly — cooler ambient temperatures keep panels closer to their Standard Test Conditions output during winter months. A six-kilowatt Chicago system at fourteen cents per kilowatt-hour produces approximately nine hundred to one thousand fifty dollars of annual bill savings depending on the net metering or export credit rate.
Example ROI for a 6 kW System
- Estimated annual savings
- $950
- Payback period
- 9.5 years
- 25-year net savings
- $22,000
Run a personalized estimate with your ZIP code using the Solar ROI Calculator.
Major Cities in Illinois
- Chicago60601
- Naperville60540
- Springfield62701
- Peoria61602
- Rockford61101
Common Questions About Solar in Illinois
What is Illinois's Smart Solar Billing Program?
The Smart Solar Billing Program is the new net energy metering framework established by the Illinois Commerce Commission under Docket 24-0205, which took effect for newly interconnecting systems beginning in 2024 and 2025. Under the Smart Solar Billing Program, excess solar generation exported to the grid by new systems earns an export credit at a rate determined by the ICC's schedule rather than the full retail electricity rate that applied under the prior net metering law. Customers who interconnected their systems before the transition took effect are grandfathered at the retail-rate net metering terms for the remainder of their legacy contract term — meaning their solar export compensation is locked at the higher retail rate for the duration of that agreement. Illinois homeowners considering a new installation in 2025 or later should confirm with their installer and utility what export credit rate currently applies under the Smart Solar Billing Program, as the specifics of the credit schedule are set by ICC order and may be updated. The practical implication is that system sizing is more important than before: a system sized to cover consumption rather than produce substantial surplus tends to perform better economically under an export-credit regime than under full retail-rate net metering, because self-consumed solar avoids grid purchases at the full retail rate while surplus production earns only the lower export credit.
Is solar still worth it in Illinois after the net metering transition?
Yes, solar remains financially attractive for most Illinois homeowners after the Smart Solar Billing Program transition, with the caveat that system sizing and self-consumption patterns matter more than they did under full retail-rate net metering. The federal Investment Tax Credit of thirty percent substantially reduces installed cost, and Illinois's property tax Special Assessment provides long-term property tax protection. A well-sized six-kilowatt system in the Chicago area — designed to cover roughly eighty to ninety percent of household consumption rather than produce a large surplus — still produces meaningful annual savings at current electricity rates. ComEd and Ameren Illinois customers with above-average daytime consumption from home offices, electric vehicles, or heat pump systems benefit most, because a higher share of solar output is self-consumed at the full retail rate. The transition primarily affects systems generating large surpluses relative to household consumption; for the typical residential customer, most solar output is consumed on-site during the day, and the export credit applies only to the surplus. LBNL data suggests Illinois payback periods for well-sized systems with the federal ITC remain in the eight-to-eleven-year range, within the useful life of a modern solar panel system.
Do I need a state license to install solar in Illinois?
Yes. Illinois requires solar installers to hold a Distributed Generation Installer license issued by the Illinois Department of Financial and Professional Regulation under the Distributed Generation Act, effective since 2017. Homeowners should verify that any installer they contract with holds a current IDFPR Distributed Generation Installer license before signing a contract. The IDFPR license database is publicly searchable at the IDFPR website, allowing homeowners to confirm a contractor's license status. In addition to the state-level IDFPR requirement, Chicago and some Cook County municipalities may have separate electrical permit and inspection requirements for rooftop solar installations; local building departments can confirm local permitting requirements. The IDFPR licensing requirement is separate from and in addition to the federal ITC eligibility requirements, which do not require any particular state contractor credential. NABCEP certification — a national solar industry credential — is not legally required in Illinois but is commonly used by homeowners as a quality indicator when evaluating installers, as NABCEP-certified professionals have demonstrated technical competency through examination and experience requirements.
What is the typical payback period for solar in Illinois?
For a six-kilowatt residential solar system installed in Illinois in 2025, a typical payback period ranges from eight to eleven years after the federal Investment Tax Credit, depending on system cost, local electricity rates, and the portion of output that is self-consumed versus exported under the Smart Solar Billing Program credit schedule. A Chicago-area homeowner paying ComEd rates near fourteen to fifteen cents per kilowatt-hour, installing a six-kilowatt system at approximately seventeen thousand dollars before the federal ITC, and self-consuming the majority of solar output might expect net annual savings of nine hundred to one thousand fifty dollars, producing a payback of roughly eight and a half to ten years. A downstate Ameren Illinois customer with slightly lower electricity rates but a better solar resource in central or southern Illinois might experience a similar payback range. Over a twenty-five-year system lifespan, the net cumulative savings after the initial system cost are typically in the range of eighteen thousand to twenty-four thousand dollars for a well-sized Illinois residential system, based on current rates and assuming modest electricity rate escalation. Payback periods are most favorable for households with above-average electricity consumption, daytime usage patterns that maximize self-consumption, and systems sized appropriately for actual household load rather than producing large net surpluses.
Best Solar Installers in Illinois
Illinois requires solar installers to hold a Distributed Generation Installer license from the Illinois Department of Financial and Professional Regulation (IDFPR). Verify your installer's license status at the IDFPR public lookup before signing any contract. Additionally, look for NABCEP-certified professionals as a quality indicator — NABCEP certification demonstrates national examination and experience requirements beyond the state minimum.
- Get at least 3 quotes from different installers to compare pricing and equipment.
- Check installer ratings with the BBB before signing a contract.
- Verify contractor licensing with Illinois Department of Financial and Professional Regulation (IDFPR) — Distributed Generation Installer license. Ask for proof of a 20–25 year panel warranty.
Top Utility Companies in Illinois
ComEd (Exelon)
Service area: Chicago, Cook County, DuPage County, Lake County, Kane County, Will County, northern Illinois
Tariff: tier-2, flat
Residential rate: 13.0–15.0¢/kWh (as of 2026-05)
NEM program: Smart Solar Billing Program
Ameren Illinois
Service area: Springfield, Peoria, Champaign, Decatur, Bloomington, downstate Illinois
Tariff: flat
Residential rate: 12.0–14.0¢/kWh (as of 2026-05)
NEM program: Smart Solar Billing Program
Net Metering Policy in Illinois
- Version
- NEM transition
- Effective date
- 2024-01-01
- Buyback rate
- export-credit
- System size cap
- 2000 kW
- Grandfathering
- Pre-2024 NEM customers retained full retail-rate net metering for their legacy contract term. New interconnection applications after Smart Solar Billing Program effective date receive export credit schedule.
Smart Solar Billing Program (ICC Docket 24-0205) — export credit schedule varies by ICC order; new applications after transition date receive export credit below retail rate. Pre-2024 NEM customers grandfathered at full retail-rate net metering for legacy contract term.
Property Tax Exemption in Illinois
- Status
- partial
- Applies to
- solar-pv
Illinois Special Assessment for Solar Energy Systems (35 ILCS 200/10-5): solar value assessed at alternative valuation capped to system installed cost; the market premium a solar installation adds to home value is not added to property tax assessment. Not a full 100% exemption — assessed value reflects installed cost, not zero.