South of San Antonio, a supersized battery complex is taking shape that its backers say could reset how Texas dodges blackouts. When fully built, the Padua site will inject fast, multi‑hour energy storage at a chokepoint on the power network, parked next to older thermal plants that have long served as reliability anchors. Local officials and project developers are pitching it as a cheaper, faster way to shore up the grid than laying miles of new transmission lines or erecting more gas‑fired power plants.
San Antonio Express-News reports that Padua's first 50‑megawatt phase went into service last September. Two additional phases slated for this year are expected to bring total nameplate capacity to roughly 400 megawatts with about five hours of discharge duration. The paper notes the complex is set to become the longest‑duration battery project in Texas, strategically sited to ease a south‑to‑north transmission pinch near CPS Energy’s Calaveras Lake area. Eolian CEO Aaron Zubaty told the outlet that if those batteries had been available during Winter Storm Uri, "Uri wouldn’t have happened."
Financing, hardware and timeline
Developer Eolian says it has closed a $463 million financing package to complete Padua 2 and 3 and that the full Padua Complex is designed to deliver about 400 MW / 1.8 GWh of instant‑ramping capacity when finished in spring 2026, using Tesla Megapack systems. The company describes Padua 2 and Padua 3 as roughly 150 MW and 200 MW phases respectively, each built for long durations so they can discharge across multi‑hour scarcity windows rather than just short spikes. In a company release, Eolian and its financing partners cast the project as a strategic, near‑term way to strengthen reliability at a critical substation site. PR Newswire
Where Padua fits into CPS Energy's plan
Padua slots into a bigger local playbook. CPS Energy’s Vision 2027 calls for 1,000 MW of battery storage, and the utility says about half of that target is already under contract. In December, CPS Energy issued an RFP seeking up to 500 MW of additional battery capacity, with proposals due Jan. 30, 2026, as it works to replace retiring units while keeping customer costs in check. The procurement push is explicitly tied to the utility’s effort to juggle reliability, affordability and a growing portfolio of clean‑energy resources. CPS Energy
Policy friction: how new market rules matter
State‑level market design is helping determine how much money long‑duration batteries can actually make. ERCOT's workshop materials for the Dispatchable Reliability Reserve Service outline resource eligibility that includes a four‑hour sustained capability and startup requirements, a structure intended to give grid operators another tool to cover multi‑hour uncertainty. Some developers, including Eolian, worry that the way DRRS is implemented or procured could leave five‑hour systems at a disadvantage, and Eolian's CEO has publicly described aspects of the rollout as "discriminatory" toward projects like Padua. ERCOT
Location and duration: why the site matters
Engineers intentionally placed Padua where it can relieve congestion near CPS Energy’s J.K. Spruce and V.H. Braunig plants, pairing that geography with longer‑duration storage sized to cover a multi‑hour morning window and an evening gap, rather than only brief bursts. That siting, combined with five‑hour discharge capability, is the core of the project’s reliability pitch: soak up cheaper energy when it is plentiful and send it back when the grid is feeling the strain. Industry groups have echoed that message, arguing that longer‑duration batteries will be central to modernizing power systems as demand from data centers and broader electrification ramps up. PR Newswire; Responsible Battery Coalition
What comes next for San Antonio
Padua 1 is already online, and Eolian says Padua 2 and 3 are expected to wrap up in spring 2026, giving the region near‑term, grid‑scale storage while longer‑range transmission upgrades move through the pipeline. How widely this model spreads in Texas will hinge on future procurements, financing conditions and whether products like DRRS allow long‑duration batteries to compete on reasonably level economic terms. For San Antonio, the Padua complex is both a test case and a statement that batteries are poised to play a bigger role in simply keeping the lights on. Eolian; CPS Energy
