Stem, Prometheus complete first of three 2024 BESS projects for Arizona co-ops

LinkedIn
Twitter
Reddit
Facebook
Email

System integrator Stem Inc and developer Prometheus Power have deployed the first of three BESS projects in Arizona for utilities in the AEPCO co-operative.

The 40MWh battery energy storage system (BESS) was added to an existing 20MW solar PV plant for Sulphur Springs Valley Electric Co-op (SSVEC), part of the non-profit member-owned Arizona Electric Power Cooperative (AEPCO).

The Sulphur Springs project is one of three similarly sized deployments that Stem and Prometheus are deploying for AEPCO utilities in Arizona, all of which are expected to be online by the end of the year.

Stem is employing its Athena energy management system (EMS) software platform to operate and monitor the project. A photo provided in the announcement, shown above, indicates that the BESS units used for the project were the Stack750e that are part of system integrator Powin’s Centipede grid-scale BESS platform.

This article requires Premium SubscriptionBasic (FREE) Subscription

Enjoy 12 months of exclusive analysis

Not ready to commit yet?
  • Regular insight and analysis of the industry’s biggest developments
  • In-depth interviews with the industry’s leading figures
  • Annual digital subscription to the PV Tech Power journal
  • Discounts on Solar Media’s portfolio of events, in-person and virtual

Or continue reading this article for free

Stem Inc has been active in the co-operative utility segment which the company’s CEO John Carrington said is a significant part of the grid-scale energy storage market in the US.

“More than 900 electric co-ops across 48 states make up the largest electric utility network in the U.S. The segment is forecasted to be one of the fastest growing segments of the front-of-the-meter (FTM) market through the end of this decade and is projected to represent over 20% of all future storage deployments,” Carrington said.

Stem Inc said in May that it expected positive EBITDA in 2024 despite a dip in revenues and bookings in the first quarter of the year, something seen by other US-focused system integrators.

Arizona meanwhile continues to grow as a major energy storage market in the US, among the most active behind leaders California and Texas. In the last few months, Leeward signed a cross-border PPA for a 450MWh BESS, Plus Power secured US$82 million tax equity for a BESS project while the largest in the state was brought online by SRP and NextEra.

Read Next

Premium
October 7, 2025
Energy-Storage.news Premium hears from a representative from Honeywell and Alejandro Schnakofsky, CTO of Prevalon, on fire safety in the battery energy storage system (BESS) industry.
October 7, 2025
Utility CPS Energy and IPP Eolian have begun operating Padua 1, a 50MW/100MWh battery energy storage system (BESS) located in Bexar County, Texas, US.
October 6, 2025
Nightpeak Energy has announced commercial operations of its 150MW/300MWh Bocanova Power battery energy storage system (BESS) in Brazoria County, Texas, US.
October 3, 2025
EDF Renewables has brought its 300MWh Milagro project online in New Mexico, while Enlight Renewable Energy has secured US$340 million in tax equity financing for its 940MWh Roadrunner project in Arizona.
October 2, 2025
Major US utility company Duke Energy has filed its biennial long-range energy modernisation plan for North and South Carolina, US. The plan includes a 5,600MW battery storage target.

Most Popular

Email Newsletter