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On October 21, 2025 parties filed exceptions to hearing examiners October 6th proposed order (PO) regarding Ameren’s 2028-2031 Grid Plan.

Among other things the proposed order would:
(1) in response to significant DER interconnection backlogs: (i) adopt a “Massachusetts-style cost allocation approach for hosting capacity upgrades” to ensure “upgrade costs are ultimately paid by DERs”; (ii) direct Ameren to engage in a cost-allocation stakeholder process, filing a report in 7/27; (iii) find that Ameren is taking appropriate next steps in analyzing flexible resource by “evaluating these programs through a geo-targeted demand response pilot, DERMS development, flexible interconnection work, and VPP functionality”; (iv) decline to approve Ameren’s proactive hosting capacity investments and funding, saying that “To the extent these are costs that would be allocated to DERs, the costs can be included in the Massachusetts-style cost allocation”; (v) approve Ameren’s request for additional interconnection process employees;

(2) approve Ameren’s agreement with Joint Non-Governmental Organizations (JNGO) to work with JNGO and other stakeholders to: (i) “develop a flexible interconnection implementation plan… by the end of Q3 2027”; (ii) “evaluate the flexibility-first pilot, post-Grid Plan approval, to inform the design of Ameren’s comprehensive VPP proposal and iterations on their existing NWA framework”; and (iii) “track additional DER data along with broadening DER registry concepts”; and

(3) approve Ameren’s Grid Strengthening Program on the conditions that it: (i) “must have a process in place to ensure that costs are allocated to DERs consistent” with the cost-allocation decision; and (ii) clarify “the costs to ratepayers that remain after costs have been allocated to DER.”

In response, parties filed exceptions to the proposed order as highlighted below:

(1) AG and Staff objected to the PO’s approval of Ameren’s reactive hosting capacity investments as proposed, with AG arguing Ameren “has not provided evidence to support the proposed budget of $25.2 million” and Staff noting that it had “identified remaining gaps concerning the individual investments expected to comprise the portfolio, how those investments would be selected and prioritized, the specific system constraints they would address, the measurable DER-related outcomes expected, and the basis for the forecasted expenditures”;

(2) AG said that while it “generally support the PO’s recommendation to adopt a cost sharing and allocation methodology that ensures ‘hosting capacity upgrade costs are ultimately paid by DERs’,” the order should “allow for flexibility in establishing an appropriate cost allocation approach” rather than committing to the Massachusetts-style approach; and

(3) Joint Solar Parties (JSP) recommended ICC: (i) “approve Ameren’s proactive hosting capacity proposal with DER that rely on such upgrades to interconnect paying for hosting capacity benefits”; (ii) move “stakeholder collaboration regarding Massachusetts-style cost allocation… [to] a docketed proceeding that ends in a Commission order”; and (iii) address JSP’s proposed changes to Ameren interconnection policies rather than sampling returning “to square one in the Interconnection Working Group.”

Replies to exceptions due by November 4, 2026.