Arizona Utilities Proposed Shift to Markets+ Energy Grid
APS and Tucson Electric Power seek improved grid efficiency through a planned move to the regional trading market.
Updated on Oct. 13, 2026 in Utilities
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Arizona utilities have submitted letters to the Arizona Corporation Commission detailing plans to join the Markets+ energy trading platform. The transition aims to address rising demand and intermittent power sources, with operations expected to launch in 2027.
Why it matters
Utilities are seeking to optimize grid reliability and lower costs amid increasingly complex resource demands. By moving to a new platform, these companies look to secure greater long-term value for customers in a shifting regional power landscape.
APS projects annual savings of $24 million to $48 million by joining Markets+ compared to $10 million to $13 million under the Western Energy Imbalance Market's day-ahead option. These figures evaluate the fiscal efficiency of two competing regional trading frameworks.
The players
APS
Arizona's largest investor-owned electric utility serving over one million customers.
Tucson Electric Power
An electric utility provider delivering power to customers across Southern Arizona.
Arizona Corporation Commission
The state regulatory body that oversees public utility rates and energy market strategies.
Lea Márquez Peterson
A commissioner at the Arizona Corporation Commission overseeing utility oversight and regulatory policy.
Nick Myers
A commissioner at the Arizona Corporation Commission who supports the transition to Markets+.
The details
Utilities use day-ahead markets to coordinate resource needs and initiate energy trades before real-time usage occurs. Unlike the Western Energy Imbalance Market, Markets+ requires participants to adhere to strict Western Power Pool resource adequacy standards. APS and TEP maintain that neither market participation replaces their underlying obligation to maintain sufficient installed generation capacity.
Timeline
September 23, 2026: Commissioner Peterson requested utility impact reports.
October 9, 2026: Deadline for utility responses to the commissioner.
2027: Markets+ is scheduled to begin operations.
2028: California completes WEIM governance transfer.
Market Landscape
This transition signals a major shift from the Western Energy Imbalance Market, currently managed by the California Integrated System Operator. The move follows a broader industry trend of reevaluating grid governance and resource standards ahead of the 2028 WEIM governance transfer.
Operators should track how these grid changes influence long-term energy procurement costs and resource adequacy requirements. Monitoring the commission's final decision on market participation will be essential for managing future utility expense volatility.
The takeaway
The move to Markets+ highlights a push for regional energy strategies that decouple from California-based market controls. Operators should watch for the final commission assessment of these proposals to anticipate potential changes in regional power reliability and cost benchmarks.
What happens next
Markets+ is scheduled to commence operations in 2027.
Further reading
Learn more about local grid developments in the Utilities section.
Source note: This article includes information reported by KJZZ.
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