Illinois has committed real money to geothermal energy credits — up to $10 million per year through 2035, funded by utility-collected RPS charges — but payments haven't started yet. The Clean and Reliable Grid Affordability Act (CRGA), signed into law in January 2026, creates a geothermal credit program for new systems (operational on or after June 1, 2026) with first credit delivery expected in 2028. If you own or are considering a geothermal heat pump in Illinois, here's what the program looks like and how to prepare.
For background on how geothermal credits work across all states, see our main geothermal credits guide.
Illinois · 2026 program snapshot
IllinoisGeothermal credits at a glance
Enacted — first credits 2028
Clean and Reliable Grid Affordability Act (CRGA) · P.A. 104-0458 · signed January 8, 2026 · administered by the Illinois Power Agency (IPA)
- Up to $10M/year in funding through 2035
- At least 40% paid upfront
- At least 33% reserved for residential
- Run by the IPA, not PJM GATS
- Estimated credit value
- $35–50/credit
- 2026 projection — no real market price exists yet
- Typical residential system
- ~50GRECs/yr
- Very roughly $1,750–$2,500 a year at the estimated range
- Contract length
- 15years
- At least 40% paid upfront when your system is switched on
- First credit delivery
- 2028
- Program rules from the IPA not yet published
Timeline at a glance
- Signed Jan 8, 2026Law enactedThe CRGA becomes P.A. 104-0458, creating Illinois's geothermal credit program
- In progress · date TBDIPA program rulesRegistration, eligibility and delivery procedures not yet published
- Expected 2028First credit delivery40% paid upfront at energization; remaining credits delivered over the contract period
- Through 2035 and beyondFunding runs, contracts continueUp to $10 million per year in utility-collected RPS funding through 2035; 15-year contracts run beyond that date
Every Illinois figure is an estimate. The market hasn't opened, so no real credit price exists yet. Values are projections as of 2026, not a promise.
The law: Clean and Reliable Grid Affordability Act (CRGA)
The CRGA — enacted as P.A. 104-0458 and signed January 8, 2026 — is the law that creates Illinois's geothermal credit program. It establishes a framework where homeowners can earn annual income from the clean thermal energy their geothermal systems produce, the same basic model that Maryland and Pennsylvania already use.
Key provisions:
- Up to $10 million per year in program funding through 2035, collected through utility RPS charges (not state-appropriated funds)
- New systems only: the program covers systems operational on or after June 1, 2026. Existing systems installed before that date are not eligible.
- First credit delivery in 2028 — the program isn't active yet
- Administered by the Illinois Power Agency (IPA), which will publish program rules, manage registration, and oversee credit delivery
- At least 33% of each annual credit block reserved for residential systems — meaning homeowners have a protected share of the pool
- 15-year contracts, giving system owners a long, predictable payment horizon
How much could you earn?
All Illinois credit values are estimates as of 2026 — no real market exists yet. Here's the best current picture:
- Estimated credit value: $35–50 per GREC. This range is a Flett Exchange placeholder estimate, not a market-established price. The actual value will depend on supply, demand, and program rules once the market opens.
- A typical residential system: about 50 GRECs per year. At the estimated range, that works out to very roughly $1,750–$2,500 per year — but treat this as a planning estimate, not a promise.
- 15-year contracts lock in participation for the long term, though the credit price itself may move with the market over that period.
- At least 40% paid upfront when your system is switched on — a feature unique to Illinois. This upfront payment makes the payback math different from Maryland or Pennsylvania, where income arrives only as credits are generated and sold. Final procedures for this upfront payment are subject to program rules the IPA has not yet published.
For context: Maryland homeowners currently earn roughly $3,567/year in gross credit value at ~$87 per credit. Pennsylvania credits trade around $26 each. Illinois is expected to fall between these two markets, but the final number will depend on how the program's supply and demand balance out.
What makes Illinois different from active markets
Illinois's program has several features that set it apart from the Maryland and Pennsylvania markets that are running today:
The upfront payment. In Maryland and Pennsylvania, you earn credits over time as your system produces energy. Illinois plans to pay at least 40% of your contract value when your system is switched on. That's a significant portion delivered upfront rather than spread across years — details subject to IPA program rules.
It's utility-funded, not state-appropriated. Maryland and Pennsylvania GRECs are sold on the open market through PJM GATS. Illinois funding comes from utility-collected RPS charges (up to $10M/year), which creates a different market structure. The IPA will administer the program directly rather than routing through PJM GATS.
Residential carve-out. The 33% minimum for residential systems is a deliberate choice to protect homeowner access to the program.
Side by side: Illinois vs. the active markets
| Maryland | Pennsylvania | Illinois | |
|---|---|---|---|
| Status | Active | Active | Enacted — first credit delivery 2028 |
| Credit price | ~$87/credit | ~$26/credit | Est. $35–50/credit (Flett placeholder, no market yet) |
| How credits are sold | Open market via PJM GATS | Open market via PJM GATS | Utility-funded (RPS charges), IPA-administered |
| When you're paid | As credits are generated and sold | As credits are generated and sold | At least 40% upfront at energization; the rest over a 15-year contract |
How to prepare right now
The program doesn't start until 2028, but there are things you can do now:
- If you're considering geothermal, start planning.Installation takes time, and having a system in place before the program opens means you won't be waiting to install after the rules are published. Compare quotes from geothermal installers in Illinois.
- If you already have a geothermal system, keep your records.You'll likely need proof of installation, system specifications, and utility interconnection details (the paperwork connecting your system with your utility) when registration opens. The exact requirements will be in the IPA's program rules.
- Watch for IPA announcements.The Illinois Power Agency will publish program rules that cover registration, eligibility requirements, and delivery procedures. Those rules will determine exactly who qualifies and how.
- Don't count on specific dollar amounts.Every number on this page is an estimate based on the law's framework and market projections. Plan around the possibility of credit income, not a guarantee of a specific amount.
Frequently asked questions
When do Illinois geothermal credits start paying?
First credit delivery under the CRGA is expected in 2028. The Illinois Power Agency will publish program rules before then covering registration and eligibility. The upfront payment (at least 40%) would be triggered at system energization, with the remaining credits delivered over the contract period.
How much are Illinois geothermal credits worth?
Estimated at $35–50 per credit as of 2026, but no real market price exists yet. A typical residential system producing about 50 credits per year would earn very roughly $1,750–$2,500 per year at that range — all estimates until the market opens.
Can I register for the program now?
Not yet. The Illinois Power Agency hasn't published program rules or opened registration. You can prepare by having a system installed and your documentation organized.
Is the CRGA the same as the old federal tax credit?
No. The federal 25D tax credit — which covered 30% of installation costs — ended December 31, 2025. The CRGA creates a completely separate program: ongoing annual income based on your system's energy output, not a one-time credit at installation. Claiming the 25D credit doesn’t itself disqualify you, but note that the CRGA covers only systems operational on or after June 1, 2026 — so a system installed before that date would not be eligible regardless of 25D. For a full comparison, see the GRECs vs. 25D section on our main guide.
Ready to get ahead of the program?
If you're thinking about geothermal in Illinois, the practical move is to start planning the system itself — the credit income is a bonus on top of the energy savings a geothermal heat pump already delivers. Get a preliminary sizing estimate with our geothermal loop calculator, then compare quotes from geothermal installers in Illinois.
Plan your geothermal project
Estimate your loop size, projected costs, and available incentives — including potential credit income.
Sources and methodology
This guide uses official state legislation, regulatory filings, and program documents. All credit values, program parameters, and dates were verified against primary sources as of September 2026. Published amounts are reported as market figures or program estimates — not guarantees. Program details are monitored for changes; homeowners should confirm current terms with the relevant state agency or broker before acting.
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