Illinois Shines (formerly the Adjustable Block Program, administered by the Illinois Power Agency) is one of the most valuable solar incentive programs in the US. It pays for the Renewable Energy Credits (RECs) a system is expected to generate over 15 years — all upfront, as a lump sum. The payment goes to the installer (Approved Vendor), who passes the value to the customer as a reduction in the system price. This article explains how Illinois Shines works and how to model it in Aurora.
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How Illinois Shines works
Illinois Shines incentivizes solar by purchasing the RECs a system is expected to produce over 15 years, paid upfront as a lump sum. Key characteristics for residential distributed generation systems:
- Payment goes to the installer (Approved Vendor), not directly to the homeowner. The installer passes the value through as a discount on the system price or an incentive payment, as specified in the installation contract.
- REC value covers 15 years of expected production, paid upfront as a single lump sum.
- The number of RECs and their value is calculated based on system size and current IPA rates.
- Systems are categorized into Group A or Group B based on which utility serves the project. Group A: Ameren Illinois, MidAmerican Energy, Mt. Carmel Public Utility, and MISO-area co-ops/municipal utilities. Group B: ComEd and PJM-area co-ops/municipal utilities. Each group has different per-REC rates set by the IPA annually.
- System size is determined by the nameplate capacity of the inverter(s), not the panels.
For full program details, current REC prices, and the REC Payment Calculator, visit IllinoisShines.com.
How lump-sum REC value is calculated
Aurora models Illinois RECs as a System size incentive with a $/watt AC value. Aurora’s pre-configured Illinois REC incentives were calculated using a formula based on IPA methodology. The reference formula is:
Number of RECs = inverter kW AC × 0.1642 ÷ 1,000 × 8,760 hours/year × 15 years
The 0.1642 (16.42%) figure is the IPA’s historical capacity factor for fixed-mount systems used in earlier program years. The IPA updates capacity factor inputs in each program year, so current calculations may differ. A 5 kW AC system using this reference formula is expected to generate approximately 108 RECs over 15 years.
To convert to a $/watt AC value for Aurora, multiply the number of RECs by the current IPA per-REC rate and divide by the system's watt capacity.
Note: IPA REC rates are updated every program year (annually in June). Always check the current rates on the IllinoisShines.com Program Documents page before configuring this incentive — do not use rates from a previous proposal. Rates differ between Group A and Group B.
How to model Illinois RECs in Aurora
Aurora includes many Illinois REC incentives pre-configured in the integrated incentives database, separated by group and system size. Always check the database first before creating a custom incentive — in most cases, a pre-configured option will already match the program you need. Illinois RECs must be added manually to a project — they are not applied by default.
- Open the project in Sales Mode.
- Navigate to $ (Pricing) > Incentives.
- Click Add Incentive. A dropdown appears with all enabled incentives. Search for “Illinois SREC” or “Illinois REC” to filter the list.
- Select the appropriate incentive based on the project's group (A or B) and the system's AC size.
Note: If the pre-configured rates don’t match your current IPA values, you have two options: (1) duplicate the closest pre-configured incentive (open it and select Duplicate) and update the $/watt AC value to match current IPA rates, or (2) create a new custom System size incentive from scratch using the calculated $/watt AC value for your group.