Solar Cost Per Watt in Illinois
Average $$3.10/W • Rank #$31 of 51 • 14.4-year payback • Updated 2026
Urgent tax credit deadlines
- Section 30D EV credit (up to $7,500) — expires June 30, 2026 (12 days left).
- Section 48E solar ITC safe harbor — construction must start by July 4, 2026 (16 days left).
Cost Per Watt
$3.10
avg in Illinois
vs National
+$0.03
(+1.0%)
Payback (8kW)
14.4 yrs
avg
Sun Hours/Day
4.3
peak
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Cost Per Watt by System Size in Illinois
Cost per watt typically decreases for larger systems (economies of scale).
Bars show Illinois's $/W for each system size. Lower = better value.
| System Size | Cost Per Watt | Total Cost | vs National Avg |
|---|---|---|---|
| 4 kW | $3.41/W | $12,400 | +$0.34 |
| 5 kW | $3.26/W | $15,500 | +$0.19 |
| 6 kW | $3.16/W | $18,600 | +$0.09 |
| 7 kW | $3.10/W | $21,700 | +$0.03 |
| 8 kW | $3.04/W | $24,800 | $-0.03 |
| 10 kW | $2.94/W | $31,000 | $-0.13 |
| 15 kW | $2.85/W | $46,500 | $-0.22 |
Solar Cost Overview for Illinois
In Illinois, the average installed cost for residential solar is $3.10 per watt, with typical systems ranging from $3.10/W to $3.10/W depending on the installer, equipment quality, and roof complexity. Illinois ranks #31 out of 51 states (1 = cheapest) for solar affordability — 30 states have cheaper solar.
Illinois is near the national average — solid value with good installers.
What's Driving Illinois's Solar Costs?
Illinois's $$3.10/W average reflects a combination of near average equipment costs, above-average local utility rates ($0.160/kWh vs national avg $0.1490/kWh), and below-average solar resource (4.3 sun hours/day vs national avg 4.7).
Note on panel pricing: Prices shown reflect AVL/DomCon-compliant panels that qualify for IRA bonus credits. Non-compliant panels (Mission, JA, Canadian) are available from $0.37/W panel-only but do NOT qualify for the 30% federal tax credit or IRA bonus credits. Learn about panel compliance costs →
Illinois Solar Incentives & Policies
Net Metering
Full retail net metering
State Tax Credit
None
Property Tax Exemption
Yes
Sales Tax Exemption
No
⚠ 2026 Federal ITC Update
The Section 25D residential solar tax credit (30%) expired December 31, 2025. Owned residential systems installed in 2026 no longer qualify. The 48E ITC (30%) remains available for lease/PPA, commercial, and rental properties that begin construction before July 4, 2026.
States With Similar Solar Costs
| State | Avg $/W | vs Illinois | Payback | Sun Hours |
|---|---|---|---|---|
| Illinois (you) | $3.10 | — | 14.4 yrs | 4.3 |
| Minnesota | $3.10 | +$0.00 | 12.3 yrs | 4 |
| Oregon | $3.10 | +$0.00 | 14.9 yrs | 4 |
| Virginia | $3.10 | +$0.00 | 14.6 yrs | 4.7 |
| Washington | $3.10 | +$0.00 | 14.2 yrs | 3.7 |
| Michigan | $3.00 | $-0.10 | 12.9 yrs | 4.3 |
Illinois Solar Cost FAQs
How much do solar panels cost in Illinois?
Is Illinois a cheap or expensive state for solar?
What is the payback period for solar in Illinois?
Does Illinois have net metering?
What solar incentives are available in Illinois?
How many peak sun hours does Illinois get?
Related Tools
Illinois cost-per-watt data based on 10 ZIP code samples. Production estimates use NREL PVWatts V8 (azimuth 180°, tilt 30°, array_type 1, module_type 1, losses 14%). Utility rate averages from NREL Utility Rate API V3. The federal Section 25D residential solar tax credit expired December 31, 2025.