SRP's 1,675 MW Marigold Project Heads to September Board Vote
Salt River Project plans to bring the Marigold Energy Center before its board for approval in September, Utility Dive reports, teeing up a mixed-resource buildout roughly 45 miles south of Phoenix to serve growing demand in Maricopa and Pinal counties.
Market Impact
The Marigold project totals up to 1,675 MW of capacity: 400 MW of battery storage, 600 MW of solar generation and up to 675 MW of gas generation, plus a new substation and four miles of 230-kV transmission line, according to SRP. The utility first announced the project last year and has held informational sessions in Stanfield, Arizona, the community closest to the site, in December and March.
SRP is now adding two more public touchpoints ahead of the board vote: an in-person open house July 28 in Stanfield and a virtual open house July 29. The utility says the project supports its push to add “reliable and affordable power to keep up with economic growth.” There’s also a potential local offtake angle: Electrical District No. 3, a regional public power utility, is evaluating a partnership with SRP to buy a portion of Marigold’s output to serve its own customers.
Marigold fits into a broader pattern of storage additions on SRP’s system. In June, the utility struck a deal with Google-backed Energy Dome for a 19-MW, 10-hour CO2-based battery system at the Coronado Generating Station in St. Johns, Arizona, a project picked through a 2024 RFP. Last October, SRP also selected ESS Tech to build a 5-MW/50-MWh iron flow battery pilot.
What It Means for Subcontractors
- Mark the September board vote as the go/no-go trigger. Contractors in gas, solar and battery storage scopes should treat SRP board approval as the signal that subcontract packages for Marigold move from planning to procurement.
- Attend the public meetings to get ahead of scope details. The July 28 in-person session in Stanfield and July 29 virtual open house are the near-term venues where SRP is expected to share project specifics relevant to civil, electrical and substation work.
- Prep for a four-mile 230-kV transmission scope plus new substation build. Line crews, E&I contractors and substation specialists should start assembling qualifications now, since this scope is confirmed regardless of final generation mix.
- Battery and gas equipment suppliers should track SRP’s RFP pattern. Both the Energy Dome CO2 battery (selected via a 2024 RFP) and the ESS Tech iron flow project came through competitive procurement, suggesting Marigold’s 400 MW storage and up to 675 MW gas components will likely follow a similar bid process once board-approved.
- Watch for a potential ED3 offtake deal, which could affect load-serving arrangements and open additional local contracting relationships in Pinal County beyond SRP’s direct scope.
