1,000MWh Arizona Battery Storage Goes Live: Inside Aypa Power's Pediment Project
Arizona just took a giant leap forward in grid-scale energy storage. Developer-operator Aypa Power and utility Salt River Project (SRP) have officially brought the 250MW/1,000MWh Pediment battery energy storage system online in Mesa, Arizona — marking one of the largest operational BESS installations in the American Southwest and a milestone for the region's clean energy transition.
This 1000MWh Arizona battery storage project represents more than just impressive capacity numbers. Located in the Elliot Road Technology Corridor, it sits at the intersection of Arizona's booming data center economy and its growing need for reliable, dispatchable power. For a state that routinely faces extreme summer demand peaks, the timing couldn't be better.
From Acquisition to Operation: The Pediment Timeline
Aypa Power acquired the Pediment project from independent power producer Eolian in 2024, and the speed of execution since then has been remarkable. By December 2024, the company had closed a $398 million financing package led by French bank Société Générale, with ING Capital and Bank of America serving as coordinating lead arrangers. Construction created over 200 jobs, and the project is projected to deliver more than $16 million in direct economic impact to Maricopa County over its first 20 years — including $14 million in property tax revenue.
The Pediment BESS is only the beginning for the Aypa-SRP partnership. A second 250MW/2,000MWh lithium-ion BESS is already in development for SRP, with operations scheduled to begin in December 2028. That 8-hour duration system would represent another step-change in storage capability for the utility.
SRP's Breakneck June: Three Projects, One Vision
SRP has been on an extraordinary deployment sprint this month. Just days before the Pediment announcement, the utility and EDP Renewables North America completed the 200MW/800MWh Flatland Energy Storage project. And earlier this week, SRP took a bold step into non-lithium territory, announcing a 19MW/190MWh carbon dioxide-based long-duration energy storage project with Energy Dome in St. Johns, Arizona — selected through a request for proposals issued in partnership with Google. Shop now for AGAIC POWER's LiFePO4 batteries, designed for the reliability that utility-scale projects demand.
Collectively, SRP has brought over 1,800MWh of new storage capacity online or under contract in a single month. That's the kind of deployment velocity that turns energy transition ambitions into grid reality.
The Financing Engine Behind the Buildout
Aypa Power's ability to move at this speed is backed by serious financial firepower. Earlier this year, the company closed a $1.5 billion construction warehouse revolving credit facility — what it described as the largest warehouse financing for a storage-focused IPP — with an additional $500 million accordion feature. It then upsized that facility by another $500 million shortly after, bringing total available capital to $2.5 billion for projects expected to become operational through 2028.
This financing structure is worth watching because it represents a maturation of the BESS project finance market. Warehouse facilities of this scale were unheard of for standalone storage just a few years ago. Their emergence signals that institutional lenders now view battery storage as a bankable, predictable asset class — not a speculative technology bet.
What Mesa Means for the Southwest Grid
The Pediment project's location in Mesa places it squarely in one of America's fastest-growing metropolitan corridors. The Phoenix metro area's combination of population growth, industrial expansion, and data center development is driving electricity demand at rates that few other US regions can match. Grid-scale storage is becoming not just desirable but essential for maintaining reliability as thermal generation retires and renewables penetration increases.
For businesses and communities across the Southwest, the Pediment BESS demonstrates that large-scale storage is no longer theoretical. It's online, it's delivering value, and it's creating a template for the hundreds of gigawatt-hours of storage capacity still needed to achieve a decarbonized grid. Explore our collection of residential and commercial energy storage solutions that bring utility-grade reliability to your home or business.
