ContourGlobal breaks ground on Sterling, a solar-storage plant for Tesla

ContourGlobal broke ground on October 6, 2026 on Project Sterling, a solar-plus-storage plant about 20 miles north of Lake Havasu City in Mohave County, Arizona, that will combine 509 MWp / 450 MWac of solar with a 360 MW / 1.4 GWh battery. Tesla has contracted around 90% of its expected output under a long-term power purchase agreement, the company said in its October 7 release. Construction will continue through 2028 with an average of about 400 workers, and the project page plans first energization in the third quarter of 2027 and targets commercial operation in the first quarter of 2028.

The plant is built around its buyer. ContourGlobal expects Sterling to generate more than 1.1 TWh a year from more than 760,000 solar modules and over 300 lithium iron phosphate battery containers spread across more than 2,000 acres of the Mojave Desert. "Our teams engineered the project around the specific needs of our customer, enabling it to deliver reliable clean power for up to 16 hours a day," said Antonio Cammisecra, ContourGlobal's chief executive. The battery is the part doing the stretching: 1.4 GWh at 360 MW is about four hours at full output (the power-versus-energy distinction at work), which the company's July release wrote as "360 MW/ 4 hours." Cammisecra described the job as "storing part of that energy for delivery after sunset," the evening end of the What is the duck curve?.

Tesla's contract dates to July: the July 28, 2026 release put it at about 1 TWh a year, "representing around 90% of the project's as-generated annual output," with electricity and renewable energy certificates bundled. ContourGlobal calls it its biggest PPA and one of the largest corporate solar-plus-storage PPAs ever signed for a single hybrid plant in the US. The buyer also sells grid batteries, and deployed 13.7 GWh of storage in the third quarter of 2026 alone (Tesla Q3 2026: 486,532 deliveries, 13.7 GWh of storage, no Semi figure). ContourGlobal's releases describe Sterling's containers by chemistry, liquid cooling and fire protection, and do not name their maker.

The plant is in Arizona; the power is headed for California's market. Per the July release, Sterling is physically connected to the Western Area Power Administration grid, "holds firm point-to-point transmission rights to access California's CAISO and will be pseudo-tied, enabling it to serve Tesla's needs." WAPA representatives attended the ceremony in Topock. ContourGlobal says the project is privately financed, and it has taken an equity bridge loan from a syndicate of international banks to fund part of its equity during construction.

Sterling has started construction more than once, depending on who is counting. Off-site physical work, including procurement of major equipment, began in June 2025 by the project page's timeline, and work on Polaris Road, the access route from Route 66, in July 2026. The same timeline puts "Start of construction" in September 2026, the month before the ceremony the October release describes as the start of construction. The July release counted from the earliest: "Substantial construction of the project initiated in 2025 through off-site physical work of significant nature; on-site groundbreaking is planned for 2026 and COD for 2028."

That wording has a federal echo. Under the July 2025 budget law known as the One, Big, Beautiful Bill Act, the IRS explains in Notice 2025-42, the clean electricity production and investment credits end for wind and solar facilities placed in service after December 31, 2027, a termination that applies to facilities "the construction of which begins after July 4, 2026." Construction begins, in the notice's words, "when physical work of a significant nature begins," and off-site work such as manufacturing components, racks, inverters and transformers can count. The notice's definitions except energy storage technology; the solar is covered. A solar plant reaching commercial operation in the first quarter of 2028 can therefore qualify only if its construction began by July 4, 2026, which for Sterling would mean the 2025 work, not the October 6 ceremony. ContourGlobal's releases do not mention tax credits.

Sterling is not alone on that clock. Arizona installed 1.4 GWdc of utility-scale solar in the second quarter of 2026, behind Texas's 1.7 GWdc, in a quarter when SEIA and Wood Mackenzie attributed a 61% year-over-year jump in utility-scale installations to developers placing safe-harbored projects into service before the credit window closes (SEIA/WoodMac: residential solar fell 12% in Q2 2026, utility-scale up 61%). Sterling's own date with the grid comes later: first energization in the third quarter of 2027, by the project page's plan.