Illinois solar calculator
Size an Illinois home solar system from your electric bill — kW, panel count, roof area, true cost with no federal credit for 2026 installs, and payback.
Quick answer: At $0.199/kWh and 4.3 peak sun hours, a $200/month bill needs about 10.25 kW — 25 × 410 W panels covering ~50 m². Gross cost is ~$30,135 with no federal credit for systems installed after 2025, offsetting $2,400 a year for a ~12.6 year payback.
Your details
Ballpark, not gospel. Sized at 78% real-world output with the Illinois sun-hour average — confirm shading, roof angle and your utility’s Smart Solar Billing terms with a local installer before buying. Illinois ended full-retail net metering for new systems on January 1, 2025 — new customers earn only the supply rate for exports, while pre-2025 systems are grandfathered at full retail. The calculator values all generation at your retail rate; exports earn far less, so real savings track self-consumption and batteries.
The 30% credit ended — what changed
The residential clean energy credit (26 U.S.C. § 25D) gave homeowners a 30% credit on solar installed from 2022 through 2025. The July 2025 tax law ended it: no credit is available for property placed in service after December 31, 2025. That is why every figure on this page is ~30% higher than pre-2026 guides show. If your system went live by the end of 2025, tick the box above to see the credit applied; leased systems may still benefit because the leasing company claims the commercial credit. Source: IRS — Residential Clean Energy Credit.
Typical Illinois system sizes by monthly bill
| Monthly bill | System size | Panels (410 W) | Net cost (no 2026 federal credit) | Payback |
|---|---|---|---|---|
| $100 | 5.33 kW | 13 | $15,670 | 13.1 years |
| $200 | 10.25 kW | 25 | $30,135 | 12.6 years |
| $300 | 15.17 kW | 37 | $44,600 | 12.4 years |
Computed at $0.199/kWh, 4.3 peak sun hours and $2.94/W installed, with no federal credit for 2026 installs. Run your exact bill above.
Solar in Illinois: the details
Solar cost in Illinois
Solar sits in the middle of the national price range in Illinois. The EnergySage marketplace averaged about $2.94 per watt installed in 2026, with market quotes typically landing $2.50–$3.38/W — within the $2.50–$3.50/W national band. A typical ~13 kW Illinois system grosses around $38,220 before any Illinois Shines SREC payment, with no federal credit for 2026 homeowner installs.
What moves the number: roof complexity, panel tier, and how competitive the quote market is in your metro. Get at least three quotes — spreads of $0.50/W between installers are common.
Export rules: getting paid for surplus power
Full retail net metering ended for new Illinois systems on January 1, 2025. New customers are on ‘Smart Solar Billing,’ which credits exports at the supply rate only; systems installed before 2025 are grandfathered at full retail. Post-2024 exports earn roughly 40% less than they used to.
Practical takeaway: the export credit is no longer the engine of an Illinois payback — self-consumption and the Illinois Shines SREC payment are. Size for your daytime load, and run the calculator above against your actual export terms.
Illinois solar incentives
The Illinois Shines (Adjustable Block) program pays homeowners SREC incentives for 15 years of system generation, typically delivered as an upfront payment through an approved vendor. Under Smart Solar Billing’s weaker export credits, the Illinois Shines payment is now the biggest lever in the payback math.
No major statewide solar tax credit beyond that was found in 2026 sources.
Is solar worth it in Illinois?
Verdict: marginal on the calculator alone. The calculator puts a $200/month bill at a ~12.6-year payback with no federal credit, and new systems earn only the supply rate for exports. The Illinois Shines SREC payment — usually paid upfront through an approved vendor — is what can pull that number back toward reasonable. If you use power during the day and qualify for a strong Illinois Shines block, it works; as a pure export play, it doesn’t.
Questions people actually ask
Straight answers, no fluff. Then run your own numbers above.
How many solar panels do I need in Illinois?
It follows your bill. At the Illinois average of $0.199/kWh and 4.3 peak sun hours, a $200/month bill needs about a 10.25 kW system — roughly 25 × 410 W panels covering ~50 m² of roof.
What is the average cost of solar panels in Illinois in 2026?
The EnergySage marketplace averaged about $2.94 per watt installed in 2026, with market quotes typically $2.50–$3.38/W — within the $2.50–$3.50/W national band. A typical ~13 kW system grosses around $38,220, with no federal credit for 2026 homeowner installs.
Does Illinois have net metering?
Full retail net metering ended for new Illinois systems on January 1, 2025. New customers are on Smart Solar Billing, which credits exports at the supply rate only — and systems installed before 2025 are grandfathered at full retail.
Does Illinois offer any solar tax credit or rebate?
The Illinois Shines (Adjustable Block) program pays homeowners SREC incentives for 15 years of system generation, typically delivered as an upfront payment through an approved vendor. No major statewide solar tax credit beyond that was found in 2026 sources.
Is the 30% federal solar tax credit still available?
Not for homeowner purchases anymore. The residential clean energy credit (26 U.S.C. § 25D) is not available for property placed in service after December 31, 2025, under the July 2025 tax law (Public Law 119-21). Systems installed by the end of 2025 can still claim 30%, and leased systems may still benefit because the leasing company claims the commercial credit instead. (Source: IRS — Residential Clean Energy Credit.)
Is solar worth it in Illinois?
Marginal on the calculator’s math: a ~12.6-year payback with no federal credit, and new systems only earn the supply rate for exports under Smart Solar Billing. The Illinois Shines SREC payment — usually paid upfront — is the lever that can rescue the payback, and high daytime self-consumption matters.
Figures last checked October 2026. Sources: EIA Electric Power Monthly (July 2026: 19.89¢/kWh), NREL PVWatts/NSRDB (~4.3 peak sun hours), DSIRE, Illinois Commerce Commission; IRS — Residential Clean Energy Credit.
More US solar calculators
Compare other states: Texas, Florida, California, Arizona, North Carolina, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts. And the national US solar calculator for country averages.
Comparing quotes? The solar cost calculator breaks down cost per watt and the solar ROI calculator maps your payback year by year. Going deeper: installation cost guide, how net metering works, how much you can save with solar and the solar batteries guide.