Solar Panel Cost in Illinois: $3.02/W, 23.0-Year Payback

Solar in Illinois costs about $24,160 for 8 kW at $3.02/W and pays back in roughly 23.0 years at 19.2¢/kWh with the federal credit at $0.

Updated September 2026 · Source: EIA Electric Power Monthly Table 5.6.A (July 2026 data) · next EIA update ~Oct 23

By SolarCostData Data Desk · Reviewed September 2026 · Corrections log

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Why this number

Solar panels in Illinois cost about $3.02 per watt — $24,160 for a typical 8 kW system — and pay back in roughly 23.0 years at the state’s 19.2¢/kWh average rate, with the 2026 federal credit at $0. Net billing pays exports below retail here.

Everything below uses Illinois’s real average residential electricity rate (19.2¢/kWh, EIA) and a production band of about 1,245 kWh per kW per year. Both are stated openly because they are the two inputs that decide the answer. These are estimates for sanity-checking a quote, not a quote.

Run it with your own numbers

Why Illinois’s payback lands where it does

Illinois residents paid 19.2 cents per kilowatt-hour on average this July, up about twelve percent from 17.22 cents a year ago and good for rank 16 among the fifty states. A modest yield of 1,245 kilowatt-hours per installed kilowatt keeps the payback at a lengthy 23 years despite that above-average rate. The gap that stands out here is Commonwealth Edison’s: the Chicago-area utility, with nearly 3.73 million residential customers, actually bills just 13.4 cents on average — well below the 19.2-cent statewide figure — which means most Illinois solar owners, concentrated in ComEd territory, are working from a materially lower rate and a longer real-world payback than the state number implies. Illinois compensates exports under net billing rather than full retail, so a ComEd customer’s solar math depends even more on that 13.4-cent self-consumption baseline than on the statewide blend, since exported power is paid well below it.

Electric utilities in Illinois

The state average hides real spreads between utilities. The largest residential utilities EIA-861 lists for Illinois, with each one’s own average bundled residential price (2024 — revenue ÷ sales, the audited annual figure, not this month’s tariff):

Your utility decides Illinois’s real number — the ZIP lookup finds it in three clicks; the 2024 annual utility averages above sit apart from the June-2026 monthly 19.2¢ state figure.

Illinois’s rate, the last 24 months

July 2025 → July 2026: 17.22¢ → 19.22¢. The rate tracker has every month against the US average.

An 8 kW system in Illinois, priced out

The $3.02/W used above comes from EnergySage marketplace quotes (August 2026). Those are quotes in a competitive online market, not signed contract prices.

Read that table with one caveat: $3.02/W is Illinois’s market average, and it is the input most likely to differ for you. A quote $0.50 per watt above or below the $3.02 used here moves the payback by roughly a year and a half in either direction.

How much sun Illinois actually gets

A kilowatt of panels in Illinois produces about 1,245 kWh a year on an unshaded, south-facing roof at a 20-degree pitch. Sites that swap Illinois’s 1,245 kWh for a single national average are how Arizona and Washington end up with identical paybacks despite a 1.6x real difference in output.

That figure is a five-point cluster around Illinois’s largest metro area, which keeps it representative of where most people actually live rather than of the state’s best site.

City-level figures for Illinois

We have separately modeled production for 3 Illinois cities, and they are 5% apart — Chicago at 1,235 kWh per kW against Springfield at 1,296. Installed cost held at $3.02/W; paybacks use each city’s own utility tariff and export treatment where we have official EIA-861 data, which is why some differ sharply from this page’s state-average model.

• Springfield — 1,296 kWh per kW, payback about 20.9–33.0 years (on its own utility’s tariff)
• Rockford — 1,249 kWh per kW, payback about 31.0 years (on its own utility’s tariff)
• Chicago — 1,235 kWh per kW, payback about 31.3 years (on its own utility’s tariff)

Those are real PVGIS-NSRDB location points, not the state figure scaled by guesswork. All Illinois and other city figures .

Two adjustments matter before you apply this to your own roof:

• Shading and orientation. The 1,245 kWh figure assumes an unobstructed south-facing array. A real Illinois roof — its own azimuth and pitch, a tree or a chimney — typically produces 10-25% less; this page models 90% of the ideal, so the 8,964 kWh/year above is already derated from 9,960. A genuinely unshaded south roof can adjust upward in the calculator.
• Year-to-year weather moves output by roughly ±5% either way.

How Illinois compares with the other 49

Illinois ranks 16th of 50 on electricity price and 18th on annual output value per kW installed — close enough that its rate is a fair proxy for its solar case, which is not true everywhere. Its immediate neighbors on price are Ohio (19.4¢) just above and Wisconsin (19.1¢) just below.

Ohio is Illinois’s closest comparable-rate analogue — 19.4¢/kWh, roughly 1,215 kWh per kW, and a payback about 1.7 years apart (21.3 vs 23.0 years). Use it as a directional marker rather than a proxy — the gap is real.

Net billing: the rule that decides solar in Illinois

Illinois does not credit exports at the retail rate — this is net billing , not net metering. The program is supply-only net metering, in force since 2025-01-01, and it credits surplus power at an assumed 5.8¢/kWh, about 30% of retail, because no per-kWh figure is published — against a retail rate of 19.2¢.

Moved from full retail to supply-only credit on 1 January 2025; delivery charges are no longer offset.

Because a typical Illinois home uses only about 40% of its generation as it is produced, most of what the panels make is sold at 5.8¢. That is why the payback above is 23.0 years rather than the 14.4 years the same hardware would return under full-retail net metering. Raising self-consumption — a battery (worth its own arithmetic: is a home battery worth it? ), an EV charged in daylight, daytime occupancy — is the lever that closes the gap. Whether a Illinois buyer should own a battery or take a lease/TPO deal is priced in the battery buy vs. TPO calculator .

One limit worth knowing: this reflects investor-owned, state-regulated utilities; Illinois’s municipal utilities and co-ops are exempt in most cases and set their own terms.

SRECs and what else Illinois still offers

The 30% federal credit ended for systems completed after December 31, 2025, so it is $0 here as everywhere. What remains is state, utility and local — and it varies far more than the federal rule ever did.

Illinois Shines (Small DG, 0-10 kW AC) — $70.37/REC in Group A and $80.77/REC in Group B over 15 years. Program year 2026-27 opened 1 June 2026 with 236.71 MW of capacity, and P.A. 104-0458 allows 50% up-front payment. This is paid on the electricity your system generates, separately from bill savings, so treat it as a range rather than a fixed line.

Tax exemptions

On property tax: Special assessment worth roughly 2.11%/yr.

If that list looks thin, it is — the solar incentives hub shows which states still put real money on the table, and where Illinois sits among them.

Is solar worth it in Illinois at 19.2¢/kWh?

Illinois is workable but unspectacular. At 19.2¢/kWh the rate does the lifting while 1,245 kWh per kW adds little, so your quoted price and your export terms decide the outcome rather than the geography.

At a horizon that long, owning the roof is not the only route to cheaper power. Community solar versus rooftop walks through the subscription alternative — no roof, no loan, and no 23.0-year wait — which is worth reading before committing capital in a market like Illinois’s.

Two numbers put that in context. At Illinois’s rate, the electricity an 8 kW system would produce is worth about $999 a year, so the system costs roughly 24.2 years of that output to buy outright — a simple division, before costs. The headline 23.0-year figure above is the full model: it additionally counts 2.5%/yr rate inflation, $150/yr of running costs and one inverter replacement, which is why the two differ slightly. And doing nothing is not free: 25 years of that same electricity, with rates rising at 2.5% a year, comes to about $58,854.

For a 15-year payback in Illinois — given its sunshine rather than a national average — the electricity rate would need to be about 18.3¢/kWh. Illinois is at 19.2¢, which is above that line.

Sources and method

• Electricity rate: U.S. Energy Information Administration, average price by state — EIA Table 5.6.A, July 2026 data (released Sep 2026). Rate shown is Illinois’s residential average.
• Production: PVGIS v5.2 with the PVGIS-NSRDB radiation database, 1,245 kWh/kW for a five-point cluster around Illinois’s largest metro, then the 90% real-roof factor; the assumptions, the ERA5 cross-check and the attribution are on the methodology page .
• Incentives: DSIRE — Database of State Incentives for Renewables & Efficiency, NC Clean Energy Technology Center. Verify current amounts and fund status before relying on them.
• Federal credit status: IRS, Residential Clean Energy Credit . See our 2026 energy tax credit guide .
• Payback model: shared with the solar savings calculator — 2.5%/yr utility inflation, 0.5%/yr degradation, federal credit $0.

Illinois’s rate (19.2¢, EIA Table 5.6.A, July 2026 data (released Sep 2026)), export regime, production factor, installed cost and programs were last verified on 25 September 2026; Illinois’s export credit resets on its tariff cycle and incentive budgets run out mid-year, so confirm current terms before acting. Not tax or financial advice.

Frequently asked questions

How we calculated this

Worked for Illinois: 8 kW × 1,000 × $3.02/W = $24,160 gross (federal credit $0, so net before state incentives); 8,964 kWh a year × the blended kWh value at 19.2¢ retail and 5.8¢ export ≈ $999 year-1 saving; payback ≈ $24,160 ÷ $999 = 23.0 years with 2.5%/yr rate growth, 0.5%/yr degradation and one inverter replacement in the 25-year model.

Sources: U.S. Energy Information Administration (EIA) electricity rates · DSIRE incentive records · public IRS/OBBBA guidance. Figures are modeled estimates, not quotes or tax advice. See our methodology.

States with a comparable tariff picture

• Why is my electric bill so high? — Splits a bill jump into weather, rate and usage — with Illinois’s own EIA rate history built in.
• Heat pump crossover temperature — Cold-zone question: the outdoor temperature where gas beats a NEEP-listed heat pump at Illinois’s rates.
• Cost to heat a home in Illinois — Gas, propane, heating oil, heat pump and resistance per MMBtu at Illinois’s own EIA winter prices — the heating side of the same rate.
• Electricity rate tracker — Illinois’s last 24 months of EIA rates, charted against the US average.
• Find your rate by ZIP — Illinois averages hide utility gaps — look yours up from EIA-861 in three clicks.
• Net metering by state (2026 table) — Every state’s export regime with program, date and source — the rule behind Illinois’s payback.
• Solar panel cost in Ohio — Same export regime at 19.4¢/kWh and a 21.3-year payback — the closest tariff comparison to Illinois.
• Solar panel cost in Indiana — Same export regime at 16.7¢/kWh and a 24.2-year payback — the closest tariff comparison to Illinois.
• Solar panel cost in Georgia — Same export regime at 16.3¢/kWh and a 23.1-year payback — the closest tariff comparison to Illinois.