State pages

Solar in Illinois

Illinois Shines changed the math in this state: renewable energy credit payments can matter as much as the electric bill. Block timing, approved vendor paperwork, and net metering terms are part of the quote, not fine print.

Production and price context

• Production: Roughly 1,100 to 1,300 kWh per kW per year, stronger in the southern half of the state. These are planning factors based on NREL PVWatts-style yields, not a roof-specific model.
• Electricity prices: Residential prices sit above the national middle, and most rooftop customers are ComEd or Ameren Illinois customers.
• Average residential price: 18.74 cents per kWh in Illinois (average price by state, 2025). Source: U.S. Energy Information Administration, Electric Power Monthly (average price by state) (source year 2025, verified 2026-10-04). For wider utility and rate context beyond rooftop decisions, see EnergyBS.

What that production range means on a roof

Put Illinois's range on the standard 8 kW example. At 1,100 to 1,300 kWh per kW per year, the lower-production band of the 13 states on this site, an 8 kW system produces roughly 8,800 to 10,400 kWh in its first year. The hardware price does not change at the state line: at the NREL benchmark of $3.25 per watt, that system is $26,000 before incentives in every state. What changes is the value of a kilowatt-hour. At Illinois's average residential price, the year-one range is worth about $1,649 to $1,949 if every kilowatt-hour offsets a retail purchase, a simple payback of about 13.3 to 15.8 years with no federal credit and no incentive subtracted. At 18.74 cents, Illinois sits in the middle of this index: neither sun nor price carries the math alone. The export rule and the share of production you use yourself tip the decision, which is why two neighbours with the same roof can get different answers from the same quote.

The headline state support is a renewable energy credit program with capped blocks that open and close, plus a separate income-eligible program. So the program stack is the lever in Illinois, not a single statewide export rule. Blocks open and close and values step down, which means the incentive inside a quote has an expiry the hardware does not. Confirm the current block and value in DSIRE before treating any incentive dollar as settled.

Hold installer promises against that 1,100 to 1,300 kWh per kW range. A promise above the top of it for any Illinois roof needs a named production tool, stated tilt and azimuth, and a shade analysis you can reproduce. A promise near the bottom on a clean south-facing roof deserves the same questions in reverse. The state range frames the conversation; the roof-specific model, with your tariff's export value inside it, settles it.

Simple payback on the standard 8 kW example, with every assumption printed

• System size: 8 kW DC.
• Gross cost: 8,000 watts at the NREL residential benchmark of about $3.25 per watt DC (2024, checked October 4, 2026) is $26,000 before any incentive. That benchmark is a comparison line for judging quotes, not a quote, a local price survey, or a price cap.
• First-year production: 8,800 to 10,400 kWh, from the Illinois planning range of 1,100 to 1,300 kWh per kW above. Planning factors only, until a roof-specific PVWatts model exists for your address.
• Value of production: every kilowatt-hour is valued at the EIA state average residential price of 18.74 cents per kWh (2025), giving a first-year value of about $1,649 to $1,949. Valuing every kilowatt-hour at the full average price overstates savings in Illinois wherever exported energy is paid below the retail rate, and wherever fixed customer charges or minimum bills apply. Your real first-year savings will be lower than this range to the extent that you export power instead of using it yourself.
• Federal credit: none subtracted. The federal residential solar tax credit ended for systems placed in service after 2025, so this example assumes no federal credit.
• State and utility incentives: no incentive value is subtracted. Any program listed for your address in DSIRE would shorten the payback if you qualify; confirm its current value in DSIRE and your utility tariff rather than trusting a value printed in a quote.
• Not modelled: panel degradation, electricity price escalation, financing costs, maintenance, roof work, and time-of-use price differences are not modelled.
• Simple payback: $26,000 divided by the first-year value range above gives a simple payback of about 13.3 to 15.8 years. Simple payback means exactly that division; it is not a return forecast.

Run your own numbers with your actual bill and quote in the estimator, check how exports are priced in our net metering guide, and read the sizing guide before deciding how much of that 8 kW example your roof should actually carry.

Incentives and export rules to verify

The headline state support is a renewable energy credit program with capped blocks that open and close, plus a separate income-eligible program. Confirm current block availability and net metering terms in DSIRE and your utility tariff; a quote that assumes an open block should name it.

DSIRE's Illinois listing covers the Future Energy Jobs Act of 2016, which funded low-income solar development and created a community solar program, and the state Renewable Portfolio Standard, which stipulates 25% of the state's energy from renewable sources by 2025. The headline rooftop structures are Illinois Shines, the Adjustable Block Program administered for the Illinois Power Agency, which provides payments in exchange for 15 years of renewable energy credits from new PV systems, and Illinois Solar for All for income-eligible households, nonprofits, and public facilities. Confirm current block availability, approved vendor status, and net metering terms with ComEd, Ameren Illinois, or MidAmerican in DSIRE and your utility tariff.

Policy summary source: DSIRE (Database of State Incentives for Renewables & Efficiency), dsireusa.org, accessed 2026-10-04. Program values are never printed here as guaranteed; name the program, then confirm its current value in DSIRE and your utility tariff.

Two sources decide what applies to your address today: DSIRE, the national database of state incentives for renewables and efficiency, for programs; and your utility's current tariff or residential solar page, for export compensation, fixed charges, and rollover rules. Program names and values change through legislation and rate cases, which is why this page tells you where to verify instead of printing a program value that could be stale on arrival.

The order of decisions in Illinois

1. Confirm the export rule and any minimum bill. That prices your surplus energy.
2. Size the system against a year of bills and the export rule, using our sizing guide.
3. Price at least three quotes against the $3.25 per watt NREL benchmark line in the estimator.
4. Only then evaluate batteries, which pay through export value and rate spreads, per our battery guide.

What matters most here

Illinois Shines changed the math in this state: renewable energy credit payments can matter as much as the electric bill. Block timing, approved vendor paperwork, and net metering terms are part of the quote, not fine print. Start from that fact when you read quotes. Ask every installer to show the production tool behind their estimate, the export value inside their payback, and the incentive owner for every dollar subtracted from the price. If the answers name documents you can check in DSIRE or your tariff, you are having the right conversation. If they name deadlines and pressure instead, our quote red flags guide lists what to ask next.