A Tesla-backed solar and battery project in Arizona has reached a major construction milestone, with Project Sterling combining 509 MWp of solar generation with 360 MW of battery storage.
ContourGlobal held a groundbreaking ceremony for the project in Topock, Mohave County, on October 7, 2026, bringing state and local officials, project partners and community representatives together to mark the visible start of the project’s major on-site construction phase.
Project Sterling will occupy more than 2,000 acres in the Mojave Desert, about 20 miles north of Lake Havasu City. The facility will combine 509 MWp of photovoltaic solar capacity, equivalent to 450 MWac, with a 360 MW battery energy storage system capable of storing 1.4 GWh of electricity. The battery will provide four hours of storage and use lithium iron phosphate (LFP) technology with liquid cooling and integrated fire protection.
Once operational, the project is expected to generate more than 1.1 TWh of electricity annually, making it ContourGlobal’s largest renewable asset worldwide.
Tesla has contracted for most of the project’s output
The project has a long-term power purchase agreement with Tesla covering approximately 1 TWh of electricity annually, representing about 90% of Sterling’s expected as-generated output.
ContourGlobal announced the agreement in July 2026, calling it one of the largest corporate solar-plus-storage PPAs for a single hybrid plant in the United States. The agreement covers bundled electricity and renewable energy certificates and will provide Tesla with long-term renewable power from the project.
The Tesla agreement also played a major role in shaping the project’s current design. ContourGlobal acquired Sterling at the development stage in December 2024 and later redesigned the project to meet Tesla’s requirements as the offtaker.
The project combines solar generation with four-hour battery storage to extend electricity delivery beyond peak solar-production hours. ContourGlobal says the facility will deliver clean power for up to 16 hours a day.
Construction will continue through 2028
The October 7 groundbreaking represents a major visible construction milestone, although work associated with the project began earlier.
ContourGlobal’s project timeline identifies June 2025 as the start of off-site physical work, including procurement of major equipment. The company began construction of Polaris Road, the project’s access road, in July 2026, and identifies September 2026 as the start of construction.
The distinction is important: October 7 marks the formal groundbreaking ceremony and public construction milestone, rather than the first physical activity associated with the project.
Construction is expected to continue through 2028 and will involve an average of approximately 400 workers. The project will require more than 760,000 solar modules and more than 300 battery storage containers.
ContourGlobal is also building Polaris Road, a 5.2-mile, or 8.4-kilometer, route connecting historic Route 66 to the project site.
The company is targeting first energization in the third quarter of 2027, with commercial operation scheduled for the first quarter of 2028.
Project connects Arizona to California power market
Project Sterling is physically connected to the Western Area Power Administration grid and holds firm point-to-point transmission rights to access the California Independent System Operator market.
ContourGlobal plans to use a pseudo-tie arrangement to serve Tesla’s contracted electricity needs. The project’s transmission position gives it access to California’s electricity market while the facility itself is located in Arizona.
The project therefore combines three major pieces of infrastructure: utility-scale solar generation, four-hour battery storage and transmission access into a major Western electricity market.
ContourGlobal says the arrangement can also support regional grid reliability by facilitating transfers across the Western Interconnection.
More than 760,000 solar modules planned
The scale of the construction effort extends beyond the generation equipment itself.
More than 760,000 solar modules will be installed across the site, alongside more than 300 battery containers. The battery system will use LFP chemistry, liquid cooling and integrated fire protection.
The project will also require civil works, road construction and site logistics as crews prepare the desert site for the solar and storage facilities.
Its location near historic Route 66 adds another infrastructure dimension to the project, with Polaris Road providing the principal connection between the highway corridor and the new energy facility.
Project is privately financed
ContourGlobal is privately financing Project Sterling and has secured an Equity Bridge Loan from a syndicate of leading international banks to support the project’s financing structure and capital deployment during construction. The company has not publicly disclosed the amount of the loan or the individual banks involved.
The project represents a significant expansion of ContourGlobal’s U.S. renewable platform.
The company says its U.S. portfolio includes about 1.2 GW of thermal generation across 10 plants in California, New Mexico and Texas, alongside renewable and storage assets. Project Sterling is now under construction and is expected to become the company’s largest renewable asset once operational.
The project also illustrates how large power consumers are increasingly securing dedicated renewable generation through long-term contracts while developers pair solar plants with batteries to extend delivery beyond daytime production.
From permitting to construction
While Project Sterling has reached the construction stage, other large-scale solar and storage developments remain earlier in the approval process. In Nevada, the Blue Mountain Solar and Storage Project is currently moving through Humboldt County’s permitting review, offering a look at the regulatory steps that projects must clear before construction can begin.
Humboldt County’s Regional Planning Commission scheduled two conditional-use permit applications for the Blue Mountain Solar and Storage Project for consideration on October 8, 2026.
The contrast illustrates the different stages that large renewable projects can occupy at the same time: while Blue Mountain remains before a local permitting authority, Project Sterling has moved into construction after securing its approvals, transmission arrangements and long-term Tesla offtake agreement.
What comes next for Project Sterling
Construction will continue through 2028 as crews build the solar field, battery storage system, access infrastructure and associated electrical facilities.
The project’s first energization is targeted for the third quarter of 2027, with commercial operations set to begin in the first quarter of 2028.
Once complete, Project Sterling will combine 509 MWp of solar generation with 360 MW of battery storage and should produce more than 1.1 TWh of electricity each year.
The project has a long-term Tesla agreement covering approximately 90% of its expected output, firm transmission rights into CAISO and a four-hour battery system. Together, these features position Sterling as a large hybrid power facility capable of delivering renewable electricity across a broader range of hours.
Construction has started on Project Sterling in Arizona, combining 509 MWp of solar with 360 MW of battery storage under a Tesla agreement.
Project Sterling: Factsheet
- Developer: ContourGlobal
- Location: Mohave County, Arizona, near Topock and approximately 20 miles north of Lake Havasu City
- Site: More than 2,000 acres
- Solar capacity: 509 MWp / 450 MWac
- Battery capacity: 360 MW / 1.4 GWh
- Battery duration: Four hours
- Battery technology: Lithium iron phosphate (LFP)
- Expected annual generation: More than 1.1 TWh
- Power purchaser: Tesla
- Tesla PPA: Approximately 1 TWh annually, representing about 90% of expected as-generated output
- Transmission: Physically connected to the WAPA grid with firm point-to-point transmission rights to access CAISO
- Access road: 5.2 miles / 8.4 kilometers of Polaris Road
- Solar modules: More than 760,000
- Battery containers: More than 300
- Construction workforce: Approximately 400 workers on average
- First energization: Targeted for Q3 2027
- Commercial operation: Targeted for Q1 2028
- Groundbreaking: October 7, 2026
- Financing: Privately financed, including an Equity Bridge Loan from a syndicate of international banks
- Long-term offtake: Tesla
- Expected status at completion: ContourGlobal’s largest renewable asset worldwide
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