FERC has approved an SPP tariff revision designed to accelerate the addition of new generation by quickly adding shovel-ready incremental capacity — up to 20% of the facility’s “maximum injection capability” — at existing generating sites.
The commission said in its Nov. 28 order that SPP’s temporary priority process “makes efficient use of the existing transmission system” by queuing eligible generator-interconnection requests higher than existing study clusters that haven’t started. It said the proposed accelerated time frame, not subject to waiting for open seasons or processing as part of a cluster or from needs driven by other requests, ensures customers can interconnect in a “reliable, efficient, transparent and timely manner” (ER25-3570).
The priority process meets FERC’s “independent entity variation standard” and its Orders 2003 and 2023-A. The process was accepted Nov. 28, became effective Dec. 1 and will be in place until March 1, 2026. That’s when SPP’s consolidated planning process, assuming FERC approves it, is to take effect. The CPP, an integrated, three-year transmission planning cycle blended with generator-interconnection studies, is planned to produce its first assessment in 2028. (See SPP Celebrates Novel Consolidated Planning Process.)
But the commission rejected two other tariff revisions by SPP: its proposals to expand eligibility for the priority process to generators retired for less than five years (ER26-153) and to modify the queue’s priority for interconnection and priority requests (ER26-153).
FERC ruled the priority request process enables SPP to meet “projected near-term resource adequacy needs more quickly” than would its existing study cluster process. It agreed with the RTO’s contention that the commission has “recognized the benefits of improved queue efficiency.”
“The priority process will improve the efficient interconnection of new generating facility capacity by allowing incremental additions to existing generating facilities to come online in an expedited manner without impacting existing interconnection customers,” FERC said, quoting its own statements.
The grid operator told the commission its current GI process “may be unable to meet the near-term resource adequacy needs” of its load-responsible entities that are “subject to a set of heightened eligibility and financial-readiness requirements.”
FERC in August approved separate planning reserve margins for the 2026 summer and winter seasons that LREs must meet; those that fall short could incur deficiency payments. The approval set a 36% PRM for the winter season and a 16% margin for the summer. (See FERC Approves SPP’s Separate Winter, Summer PRMs.)
The commission found the priority process is “narrowly tailored” to address the RTO’s near-term resource adequacy or reliability needs because it applies only to existing facilities — and just once — and because the eligibility and financial-commitment requirements “prevent speculative interconnection requests,” reducing the potential for time-consuming restudies.
Priority project owners must cover all costs of the priority system impact studies and all necessary substation network and system network upgrades.
FERC said the heightened eligibility and financial readiness criteria limit an interconnection customer’s ability to qualify for the one-time study. “These limits allow only ready projects that do not impact existing interconnection customers” to use the priority process, it said.
In rejecting SPP’s two related tariff revision proposals, the commission said the grid operator lacked details for allowing retired generators to take advantage of the priority process. It pointed to lack of clarity over whether the project could be 120% of the size of the retired generator or 20% of its size.
New ESR Load Assessment
FERC also accepted SPP’s tariff revisions that outline the study requirements for load assessments of electric storage resources (ESRs) subject to the RTO’s generator-interconnection procedures, effective Oct. 7, 2025 (ER25-3105).
The commission found that because SPP’s revisions incorporated FERC’s pro forma LGIP language from Orders 2023 and 2023-A, they were deemed just and reasonable and not unduly discriminatory or preferential. It said the deviations from the commission’s pro forma LGIP and LGIA accomplished the purposes of Orders 845 and 2023.
FERC said SPP’s proposal to define a new term in its tariff — ESR-LA, for ESR load assessment — to evaluate the effects of an ESR withdrawing energy from the transmission system, in accordance with NERC Reliability Standards, will help facilitate the reliable interconnection of new ESRs.
“SPP’s proposed revisions specify that SPP will study an electric storage resource only under off-peak conditions and then assess whether any charging limitations must be imposed on that resource,” the commissioners wrote. “Studying the resources under off-peak conditions is based on the resource’s expected real-time charging behavior, and any charging limitations will be based on the available capacity of the transmission system.”
The RTO’s proposal will apply to those interconnection requests submitted in the 2024 study cluster window.
