Tesla has agreed to buy about 1 terawatt-hour of electricity a year from Project Sterling, a solar-plus-storage plant in Arizona. ContourGlobal, the developer, says that volume is roughly 90 percent of the plant’s as-generated annual output, and that the solar side is rated at 450 megawatts of alternating current.
The agreement is not new. ContourGlobal announced it on July 28, 2026, and what changed in early October is that construction became the story.
The 90 percent and the 450 megawatts
ContourGlobal’s power purchase announcement describes a 509 MWp (peak direct-current) and 450 MWac solar array, so the 450 MW is the AC figure, the rating at the point where power leaves the plant, and the panels carry a larger direct-current nameplate. The offtake is about 1 TWh, or 1,000 GWh, per year, which the company puts at roughly 90 percent of the project’s as-generated annual output. Expected generation is more than 1.1 TWh per year. Tesla receives the power bundled with renewable energy certificates, the tradable records of each megawatt-hour’s clean origin. The gap between roughly 1.0 TWh sold and more than 1.1 TWh expected is simple arithmetic, on the order of a tenth of the plant’s output, and the documents read do not say who buys that remainder.
The same release places a battery on the site rated at 360 MW and 1.4 GWh, about four hours at full power. pv magazine’s report repeats the pairing of 450 MW of solar with 360 MW and 1.4 GWh of storage. No document read for this article gives the contract’s length or price. Electrek’s report adds that the battery uses lithium iron phosphate chemistry with liquid cooling and integrated fire protection, and that an equity bridge loan from international banks is part of the financing, a detail the company pages do not elaborate.
Transmission rights and the WAPA grid connection
Sterling sits in Mohave County, Arizona, and connects to the grid of the Western Area Power Administration, the federal power marketer that WAPA describes as part of the Department of Energy. ContourGlobal says it holds firm point-to-point transmission rights into California’s CAISO market and a pseudo-tie so the power can be delivered to serve Tesla. The pv magazine summary says the energy and certificates go to Tesla’s California operations.
The Western Area Power Administration operates high-voltage lines across a 15-state region of the West and Great Plains, according to its site, which is why the project’s interconnection and its California delivery rights are described as two separate things. A plant can be physically tied to one grid while contractually serving a buyer on another, and ContourGlobal says Sterling does exactly that.
That routing explains why a plant in the Mojave Desert counts toward a company buyer based elsewhere. The electricity is scheduled to move over the transmission rights to CAISO, rather than being consumed beside the panels, and the certificates travel with it.
Construction timeline and the dates that conflict
ContourGlobal acquired Project Sterling at the development stage in December 2024 and reshaped it around the offtaker’s requirements. Off-site work began in 2025, including major equipment procurement in June, and the July release said on-site construction would start later in 2026. Commercial operation is targeted for 2028. The project page narrows that to the first quarter of 2028 and shows first energization planned for the third quarter of 2027.
The project page is internally inconsistent about the construction start: its timeline lists September 2026 while its introduction says construction is already underway. Electrek’s October 9 report says ContourGlobal held a groundbreaking on October 6, and describes the site as about 20 miles north of Lake Havasu City on more than 2,000 acres, with more than 760,000 panels and a battery in more than 300 containers. Those site details are Electrek’s and do not appear on the ContourGlobal pages read here.
For ContourGlobal the project is a scale-up: the company says it will be its largest renewable asset to date, built on a site it bought before any offtaker was attached and then redesigned around Tesla’s requirements. First energization is planned for the third quarter of 2027, more than a year after the July announcement, and full commercial operation follows in 2028.
Antonio Cammisecra, ContourGlobal’s chief executive, framed the agreement as the largest power purchase agreement the company has ever secured, and one of the largest of its kind in U.S. renewable history, with Tesla as the offtaker. The company also calls Sterling its largest renewable asset to date. The one figure still missing is the price Tesla pays, which neither side has published, along with the contract term. Cammisecra’s description of the deal as the company’s biggest ever also leaves the dollar value unstated, so the 90 percent share and the 1 TWh volume remain the only quantities both ContourGlobal and independent reports agree on.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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