FERC has accepted SPP’s proposed revisions to its tariff that will incorporate seven Western Interconnection entities as transmission-owning members of the RTO, making the grid operator the first to provide full market services in the grid’s two major interconnections.

The commission on March 20 directed SPP to make a compliance filing within 30 days. It also required the RTO to provide a notification of the RTO West’s go-live date no later than six months prior (ER24-2184).

SPP has targeted April 2026 as when the entities will begin participating in its Integrated Marketplace, transmission planning, reliability coordination and other RTO services. They all are members of the Western Energy Imbalance Service market, which SPP has administered since 2021:

• • Basin Electric Power Cooperative
  • Colorado Springs Utilities
  • Deseret Power Electric Cooperative
  • Municipal Energy Agency of Nebraska
  • Platte River Power Authority
  • Tri-State Generation and Transmission Association
  • Western Area Power Administration’s Colorado River Storage Project, Rocky Mountain and Upper Great Plains regions

FERC agreed with the grid operator that its proposal to integrate the expansion members into its RTO likely will improve grid reliability and operational efficiency, benefiting existing members and new ones. SPP has said RTO West will provide more than $200 million in annual benefits to its members, primarily through the optimization of DC ties with the Eastern Interconnection. (See SPP Files to Incorporate Western Entities into RTO.)

“The RTO West proposal will consolidate the management of transmission facilities under a single, centrally cleared market and allow SPP to dispatch resources more efficiently across a broader geographic area,” FERC said.

“Expanding the RTO into the Western Interconnection is an exciting step in SPP’s growth, bringing value to new and existing members while enhancing reliability in both interconnections,” CEO Barbara Sugg said in a news release.

The commission filed a deficiency letter in October after SPP’s first tariff filing and asked for further clarifications on six issues, including the optimization of DC ties. (See FERC Issues Deficiency Letter for SPP’s RTO West Tariff.)

It said the RTO’s proposed DC tie access and incremental market efficiency use charges are reasonable given the “unique role that the West DC ties will play” in connecting SPP’s Western and Eastern balancing area authorities and the increased costs that will result from the ties’ use in market dispatch.

“Absent these charges, these increased costs would be borne fully by customers in the West DC ties’ transmission pricing zones because the [annual transmission revenue requirement] for each West DC tie will continue to be recovered from its respective transmission owner’s zone,” the commissioners wrote.

SPP said it is working with additional Western utilities that have expressed interest in becoming RTO members once this initial expansion is complete.

The grid operator is developing a second Western market in Markets+, a day-ahead offering centered primarily on the Pacific Northwest that secured FERC approval in January. It also serves as the program administrator for the Western Power Pool’s Western Resource Adequacy Program. (See SPP Markets+ Tariff Wins FERC Approval.)

“Multiple markets maximize value for all participants,” Sugg said.

The grid operator has expanded its footprint in the Eastern Interconnection from eight to 14 states since it became an RTO in 2004. The Western expansion will increase its service territory to all or part of 17 states.

The RTO’s expansion is part of the grid operator’s five-year strategic plan, Aspire 2026.