Quick answer
A typical 8 kW home system in Illinois lists at about $24,800 at $3.10 per watt. After the $300/kW utility rebate ($2,400) and an estimated $11,600 in Illinois Shines value, a Chicago-area ComEd homeowner pays roughly $10,800. The homeowner federal tax credit ended after 2025, so these Illinois incentives do the heavy lifting.
How much does solar cost by system size in Illinois?
| System size | Price before incentives | Utility rebate | After incentives, ComEd (Chicago) | After incentives, Ameren (Peoria) |
|---|---|---|---|---|
| 5 kW (13 panels) | $15,500 | $1,500 | $6,700 | $7,500 |
| 7 kW (18 panels) | $21,700 | $2,100 | $9,400 | $10,400 |
| 8 kW (20 panels) | $24,800 | $2,400 | $10,800 | $11,900 |
| 10 kW (25 panels) | $31,000 | $3,000 | $13,500 | $14,900 |
| 12 kW (30 panels) | $37,200 | $3,600 | $16,200 | $17,900 |
| 15 kW (38 panels) | $46,500 | $4,500 | $20,200 | $22,400 |
"After incentives" subtracts the $300/kW ComEd or Ameren rebate and our estimate of the Illinois Shines value, based on 15 years of expected production at the 2026–27 REC prices for systems up to 10 kW. Larger systems get a somewhat lower REC price, so the estimate is a bit generous above 10 kW. Most Illinois homes need 6 to 12 kW; see how many solar panels you need.
What is a normal price per watt for solar in Illinois?
- EnergySage: an average of $2.86 per watt installed in Illinois as of December 2025, from quotes on its marketplace.
- Berkeley Lab (national, 2025): a median of about $3.00 per watt for cash purchases and about $4.50 per watt for loan-financed systems, largely because of dealer fees built into loans.
- Our planning range: $2.50 to $3.50 per watt before incentives is typical; above $4.00 deserves hard questions. Check any quote with our solar quote checker.
Always compare the cash price per watt. A monthly payment can hide thousands of dollars in fees.
What makes a solar system cost more or less?
- Size: bigger systems cost less per watt because permits, design and setup are spread over more panels. Berkeley Lab found about a $1 per watt gap between the smallest and largest home systems.
- Equipment: premium panels and microinverters cost more. See are premium panels worth it?
- Roof: steep, complex or multi-plane roofs take more labor, and a roof near the end of its life should be replaced first. See replacing your roof before solar.
- Electrical work: a panel upgrade or supply-side connection adds cost, especially on large systems.
- Battery: priced separately, and partly offset by the utility's storage rebate. See the Illinois battery rebate.
- Financing: loans with dealer fees can raise the effective price by a third. See solar loans and dealer fees.
Which incentives lower the cost of solar in Illinois?
| Incentive | Amount | How you get it |
|---|---|---|
| ComEd or Ameren solar rebate | About $300 per kW | Your installer files after the system is switched on |
| Illinois Shines | About $80.77 (ComEd) or $70.37 (Ameren) per REC for systems up to 10 kW | Usually a lower price from your installer |
| Battery storage rebate | About $300 per kWh | Requires enrolling in the utility's virtual power plant program |
| Property tax rule | Home assessed as if it had no solar | File form PTAX-330 with your county |
| Federal 25D tax credit | None for homeowner-owned systems | Ended after 2025 |
See the full Illinois solar incentives guide and Illinois Shines, explained.
Is it cheaper to buy, finance or lease solar?
Paying cash gives the lowest price and keeps every incentive. A loan from a bank or credit union at a market rate, with no dealer fee, comes close. Leases and power purchase agreements cost little up front but usually save less over 25 years. See solar lease vs. buy.
To see what a system would save on your bill, and how fast it pays back, enter your bill in the solar savings calculator.
Sources
- EnergySage: Cost of solar panels in Illinois
- Mercom: Berkeley Lab Tracking the Sun, U.S. residential solar prices in 2025
- Berkeley Lab: Tracking the Sun 2024, executive summary
- Illinois Shines: Final 2026–27 REC prices for the program year starting June 1, 2026
- ComEd: Distributed generation rebate
- Citizens Utility Board: Solar and storage rebates (ComEd and Ameren)
- ComEd: Distributed generation and storage rebates
- Illinois Property Tax Code, 35 ILCS 200/10-10: Solar energy systems
- IRS: FAQs on changes to Sections 25C, 25D and other credits under the 2025 law (Public Law 119-21)
- Consumer Financial Protection Bureau: Report on markup fees in solar energy loans (2024)
- NREL PVWatts Calculator
This guide is general information, not tax, legal or financial advice. Incentive programs change, so confirm current terms with your installer, your utility and a tax professional.