Currently, there are no procurements scheduled for RECs from utility-scale solar projects under the Initial Long-Term Plan of the Illinois Power Agency (“IPA”).  The IPA has released a draft Revised Long-Term Plan released on August 15, 2019, which is available here: https://www2.illinois.gov/sites/ipa/Pages/Renewable_Resources.aspx

In this Revised Long-Term Plan, the IPA is not proposing to conduct additional competitive procurements for RECs from utility-scale solar projects at this time. Accordingly, we cannot speak to the process for submitting a proposal should an RFP for utility-scale solar projects be held in the future.

FAQ WND-1 (https://www.ipa-energyrfp.com/faqs/utility-scale-wind-faqs/?topic=general) explains the locational requirements for utility-scale wind projects; the locational requirements for utility-scale solar projects are the same.  You may want to consult the RFP Rules from the Brownfield and Utility-Scale Solar RFP that provides the requirements for proposal from the most recent procurement from RECs from utility-scale solar projects:

https://www.ipa-energyrfp.com/2018-brownfield-and-utility-scale-solar-procurement/