Illinois is a transitional state for residential solar in 2026, and one of the harder to read about online — most of the easily-found numbers are out of date or wrong. The straight reading of our calculator puts payback near ~18.8 years for a typical Chicago-area system. That's long.
Two things keep it from being shorter. First, the federal credit is gone. Second, Illinois changed residential net metering on January 1, 2025 — new installs no longer get full retail for exports. Both of those changes are still being misreported by a lot of NY-and-IL-focused solar coverage.
The reason Illinois isn't a bad market despite the long calculator number is Illinois Shines (the Adjustable Block Program). It pays you for the SRECs your system produces, and it's often paid as an upfront lump sum at install. We don't model it, but it materially shortens real payback. The number on this page is the floor, not the expected outcome.
What changed — twice
Federal credit gone. The federal Residential Clean Energy Credit (§25D) — the 30% homeowner credit — was repealed for systems installed after December 31, 2025. For 2026 Illinois buyers, the federal credit on a purchased system is $0. The same applies to home batteries purchased outright. The §48E commercial credit (30%) still exists, but only for leased or third-party-owned systems — the lessor claims it, not you. Full federal context here.
Net metering cut to supply-only. On January 1, 2025, Illinois moved new residential solar installs from full retail-rate net metering to supply-only net metering. Exports are now credited against your bill's supply + transmission charges, not delivery. Delivery is a significant chunk of an IL electric bill (often 40–60%) — so exports are worth materially less than they used to be. Systems installed before January 1, 2025 are grandfathered into the older full-retail rule, but new 2026 buyers are not.
If you see a 2024-or-earlier Illinois solar guide quoting "full retail net metering," it is outdated. Same goes for any tool that still credits exports at retail value.
VERIFIED 2026-06 · irs.govHow net metering actually works now
Self-consumption and export are now valued differently in Illinois. This matters for system sizing.
- Self-consumed solar still offsets your full retail rate — about ~$0.137/kWh. Every kWh you produce and use immediately avoids the entire bill (supply + transmission + delivery).
- Exported solar is credited against supply + transmission only, NOT delivery. That's where the $0.068/kWh figure on the calculator comes from — it's a conservative estimate of supply + transmission (~50% of retail). The exact percentage varies by ComEd vs Ameren and by your specific rate plan. Check your bill for the supply/delivery line breakdown if you want a more accurate per-utility number.
- ComEd serves northern Illinois (Chicago metro). Ameren Illinois serves central and southern Illinois (Springfield, Peoria, Champaign-Urbana). Both follow the same supply-only rule for new installs.
The practical implication: self-consumption is now significantly more valuable than export. Right-sizing your system to your actual annual usage matters more than it did under full retail. Don't oversize hoping exports will close the gap — they won't anymore.
VERIFIED 2026-06 · Illinois supply-only net metering, effective Jan 1, 2025; ICCCurrent IL retail: ~13.65¢/kWh and rising
EIA data for early 2026 puts IL residential at about ~13.65¢/kWh — above the national average and rising. ComEd and Ameren rate structures differ; both have raised rates in recent years. Higher retail rates over time make self-consumption value grow — but they don't change the export side as much under supply-only.
VERIFIED 2026-06 · eia.govFour claims you'll see online that are wrong
Illinois solar information has an unusual concentration of stale or fabricated facts. If you see any of these in a quote or article, the math behind it is incorrect.
"30% federal solar tax credit." Gone for residential purchases as of 2026. Anyone still citing 30% federal is using pre-repeal numbers.
"$10,000 Illinois state solar credit." This does not exist. Illinois has no residential solar state income tax credit. The "$10,000" figure appears to come from confusion with other programs or pure invention. There is no Illinois solar income tax credit to budget for.
"6.25% sales tax exemption." Disputed. Some sources claim Illinois exempts residential solar from the 6.25% state sales tax. The reliable answer from tax.illinois.gov is that there is no such exemption. We do not apply one in our calculator. Budget for standard Illinois sales tax on equipment, and verify with the Illinois Department of Revenue if you want to be sure.
"Full retail net metering in Illinois." Outdated. Full retail applies only to systems installed before January 1, 2025, and they are grandfathered. New 2026 installs are on supply-only.
These four claims account for most of the over-optimistic Illinois solar math you'll see online. Discount any quote that includes them.
Illinois Shines — the big lever (we don't model it)
Illinois Shines is the state's SREC program (Adjustable Block Program). It pays you for the renewable energy credits your system produces, separately from net metering. Key facts:
- Roughly $72–85 per MWh of production over a 15-year contract.
- For a typical 7 kW system, that's roughly $9,000–$10,500 of total value.
- Often paid as an upfront lump sum at install, not as an annual stream.
- The rate depends on the current block (Block 6 currently — rates step down each year as blocks fill and roll over).
- Administered through Approved Vendors — your installer signs the contract on your behalf, and a portion typically goes to them as part of their margin.
For a calculator like ours, Illinois Shines is hard to model honestly. The payment structure varies (upfront vs. stream), the block rate changes (and our snapshot would go stale), and whether you actually receive it as cash vs. price reduction depends on your Approved Vendor contract. So we don't model it.
But it is the single biggest reason Illinois solar still pays off for many buyers in 2026 despite the long calculator number. Get your specific Illinois Shines value from an Approved Vendor before deciding. A ~$9,000–$10,500 upfront payment on a system that costs ~$20,000 takes years off the displayed payback.
What Illinois does have
Property tax exemption (100%). The added home value from residential solar is exempt from Illinois property tax. This is the one IL solar incentive that's confirmed across sources without dispute.
DG Smart Inverter Rebate. Roughly $300/kW upfront for qualifying systems with smart inverters, paid by your utility. Not modeled by default but real.
ComEd / Ameren battery storage rebates. Roughly $300/kWh of battery capacity on qualifying plans. Not modeled — eligibility and current funding status varies, ask your utility.
Battery in Illinois — some arbitrage value, but not enough to pay itself back
This is where Illinois differs from the 1:1 retail net metering states (Florida, Virginia, New Mexico, Colorado, Massachusetts, New Jersey, New York legacy). In those states, the retail-export gap is effectively zero — exports earn the same rate as self-consumption, so a battery has no arbitrage value.
In Illinois, the supply-only rule creates a real gap: self-consumption at full retail ($0.137) vs. export at supply-only ($0.068). Gap ~$0.07. That's similar to Arizona's net-billing case and gives a battery some arbitrage value — you can store solar that would have earned only supply-only credit and use it later at full retail.
But ~$0.07 of arbitrage isn't enough to pay for the battery itself. On the calculator's default settings, a battery in IL still doesn't pay back its capex on energy arbitrage alone. ComEd and Ameren's ~$300/kWh storage rebate (not modeled here) and resilience value can shift the answer if you're committed to a battery — but don't expect it to shorten your solar payback. There's no federal credit on the battery purchase in 2026 (§25D repealed), either.
The honest picture
Illinois solar in 2026:
- Federal credit: $0. Not 30%. Discount any quote that says otherwise.
- No state income tax credit. The "$10,000 credit" some sources cite does not exist.
- No sales tax exemption. Disputed claims, but tax.illinois.gov says no. Budget for standard sales tax.
- Net metering: supply-only since January 1, 2025. Exports earn ~50% of retail; full retail applies only to self-consumption. Pre-2025 systems are grandfathered into the old full-retail rule.
- Retail rate: ~13.65¢/kWh, above national average, rising.
- Property tax: 100% exempt on added home value.
- Illinois Shines (Adjustable Block Program):
$72–85/MWh × 15 years ($9,000–10,500 on a 7 kW system). Often paid upfront. Not modeled here — but the single biggest reason IL solar still pays off in practice. Get your specific number from an Approved Vendor. - DG Smart Inverter Rebate: ~$300/kW upfront. Not modeled.
- ComEd / Ameren battery rebate: ~$300/kWh. Not modeled.
- Battery: some arbitrage value (unlike 1:1 states), but not enough to pay back the battery itself. Resilience case + utility rebate are the rest.
- Typical calculator payback: ~18.8 years. Real payback with Illinois Shines: meaningfully shorter — ask an Approved Vendor.
Illinois is a state where the calculator alone undersells the deal, which is the opposite of what's true in most states (where calculators often overstate it). The structural reasons solar pays off elsewhere — federal credit, full retail net metering, a real state credit — are mostly gone in IL. What's left to make solar work is Illinois Shines, which is real but hard to display as a clean number.
Before you commit:
- Discard any quote that includes a 30% federal credit, a "$10,000 IL state credit," or a sales tax exemption. All three are wrong.
- Ask your installer for your specific Illinois Shines payment — block rate, contract structure, whether it's upfront or annual, and how much of it goes to the Approved Vendor vs. directly to you.
- Don't oversize. Self-consumption is now significantly more valuable than export under supply-only. Size to your actual annual usage.
- Confirm whether you're on ComEd or Ameren — both supply-only, but retail rates and split differ.
- Ask about the DG Smart Inverter Rebate (~$300/kW) — your installer should handle it.
- Don't model a battery as a payback shortener. Some arbitrage exists, but not enough to pay for the battery; case is resilience + utility rebate.
- Run the calculator with your actual ZIP and system size to see the floor — then add Illinois Shines on top.
Estimates only — supply-only export value and Illinois Shines payments vary by utility and contract; verify with your utility, an Approved Vendor, and the ICC / tax.illinois.gov. This is not financial advice.