A worked example: 8 kW in Illinois
An 8 kW system — about 19 × 425-watt panels — at Illinois's assumed installed cost of $2.60–$3.40 per watt runs roughly $20,800–$27,200 before incentives. At about 1,270 kWh of production per installed kW, it would generate around 10,160 kWh per year. Valuing self-consumed electricity at the assumed $0.16/kWh retail rate and exports conservatively, first-year savings land near $1,339 — a simple payback of roughly 16–20 years.
There is no federal tax credit in that math: the Section 25D residential credit ended for systems installed after December 31, 2025. State or utility incentives, where they exist, would shorten payback from here.
Average cost of solar panels in Illinois by system size
Most Illinois quotes land between 6 and 12 kW. At the state's assumed $2.60–$3.40 per watt, here is what each size costs to install, what it produces, and how long it takes to pay for itself on electricity savings alone — no incentives applied.
| System size | Panels | Installed cost | Annual production | Est. payback |
|---|---|---|---|---|
| 6 kW | 15 | $15,600–$20,400 | 7,620 kWh | 16–20 yrs |
| 8 kW | 19 | $20,800–$27,200 | 10,160 kWh | 16–20 yrs |
| 10 kW | 24 | $26,000–$34,000 | 12,700 kWh | 16–20 yrs |
| 12 kW | 29 | $31,200–$40,800 | 15,240 kWh | 16–20 yrs |
Size should follow your electricity usage, not a round number — these are reference points, not a recommendation. Note that cost per watt rises on smaller systems, because permitting, labor and the inverter do not shrink with the array.
What solar costs per kWh in Illinois
Spread across a 25-year life, with 0.5%/yr panel degradation and no financing cost, solar electricity in Illinois works out to roughly 8.7¢–11.4¢ per kilowatt-hour. The Illinois retail rate this page assumes is 16.0¢. That gap — not the sticker price — is what determines whether solar pays here, and it is why a sunnier state with cheap electricity can be a worse investment than a cloudier one with expensive electricity. See how every state compares on cost per kWh.
Net metering and export rates in Illinois
Illinois ended full retail net metering for new customers in 2025; exports are now credited at the supply portion of the rate, with a distributed-generation rebate available in ComEd and Ameren territory to offset the change.
Export rules are worth reading as an incentive, because they set what every kilowatt-hour you do not use on site is worth — see how Illinois compares with every other state on net metering.
Illinois solar incentives
Illinois Shines (Adjustable Block Program) pays substantial upfront incentives for solar renewable energy credits, often worth thousands of dollars on a residential system. Verify current block pricing.
The most valuable program is illinois shines (adjustable block program). With no federal credit for 2026 installs, state and utility programs are now the whole picture — see the full Illinois incentives guide.
What changes an Illinois solar quote?
Equipment, roof condition, electrical upgrades, permitting, labor, system size, batteries and financing can all change the installed price. Savings also depend on the specific utility rate, how much solar electricity the home uses directly, and what the utility pays for exports.
Frequently asked questions
What is the average cost of solar panels in Illinois?
The average installed cost in Illinois runs $2.60–$3.40 per watt before incentives, which puts a 6 kW system at $15,600–$20,400, an 8 kW at $20,800–$27,200, and a 10 kW at $26,000–$34,000. Spread over a 25-year life, that works out to about 8.7¢–11.4¢ per kilowatt-hour, against a Illinois retail rate assumed at 16.0¢.
How much does it cost to install solar panels in Illinois?
Installation is not priced separately — the $2.60–$3.40 per watt above is a turnkey figure covering panels, inverter, racking, labor, permitting and interconnection. What moves it most in IL is roof complexity, whether the main panel needs upgrading, and whether a battery is included. Expect a site visit to change any online estimate, including this one.
How much do solar panels cost in Illinois?
Using an assumed installed cost of $2.60–$3.40 per watt, a typical 8 kW home system in Illinois costs roughly $20,800–$27,200 before incentives. Smaller and larger systems scale roughly with size, though small systems cost more per watt.
Is solar worth it in Illinois?
With Illinois electricity around $0.16/kWh and production around 1,270 kWh per installed kW per year, an 8 kW system could save roughly $1,339 in year one, for a simple payback of about 16–20 years with no federal credit. Whether that is "worth it" depends on your rate plan, export compensation, roof, and how long you plan to stay in the home.
How many solar panels do I need in Illinois?
It depends on your electricity usage, not your roof. At Illinois's assumed 1,270 kWh per installed kW, a 6 kW system (about 15 panels at 425 watts) generates roughly 7,620 kWh a year, and a 10 kW system (about 24 panels) roughly 12,700 kWh. Compare that against your annual kWh from a utility bill — our calculator sizes it from your monthly bill in about a minute.
Does Illinois have net metering?
Illinois ended full retail net metering for new customers in 2025; exports are now credited at the supply portion of the rate, with a distributed-generation rebate available in ComEd and Ameren territory to offset the change.
What solar incentives does Illinois offer in 2026?
Illinois Shines (Adjustable Block Program) pays substantial upfront incentives for solar renewable energy credits, often worth thousands of dollars on a residential system. Verify current block pricing. Note that the federal Section 25D residential credit ended for systems installed after December 31, 2025, so state, local and utility programs are now the main incentives for purchased systems.
Is there still a federal solar tax credit in Illinois?
No — the 30% federal residential clean energy credit (Section 25D) ended for systems installed after December 31, 2025 under the One Big Beautiful Bill Act. Leased or PPA systems may still benefit indirectly because the system owner can claim the commercial 48E credit through 2027.
Use this as a starting point
This page provides broad state assumptions, not a current market survey or binding quote. Before purchasing, verify applicable incentives, utility rules, installer licensing, warranties and financing terms.
Where these numbers come from
State assumptions are informed by public data and reviewed periodically (September 2026):