A new large-scale solar and battery storage project, Project Sterling, is under construction in Arizona’s Mohave County, just off historic Route 66 between Topock and Kingman. Developed by London-based power producer ContourGlobal, the facility is designed to address the challenge of solar energy production ceasing at sunset by incorporating extensive battery storage, enabling power delivery for up to 16 hours daily. Tesla has already committed to purchasing approximately 90% of the plant's output through a power purchase agreement.
The project encompasses more than 2,000 acres of the Mojave Desert and will feature more than 760,000 solar panels and over 300 battery containers. Construction activity, which began with significant off-site physical work last year, is expected to bring an average of about 400 workers to the site, potentially increasing traffic on the Route 66 stretch between Topock and Kingman. ContourGlobal aims to have Project Sterling operational by 2028. Lake Havasu City is located about 20 miles south of the project site.
Project Sterling’s design specifically addresses the intermittency of solar power. While solar panels cease generating electricity when the sun goes down, energy demand often peaks as people return home in the evening. Antonio Cammisecra, ContourGlobal’s president and CEO, stated that the project was "engineered around the specific needs of our customer." He also indicated that the plant will be capable of delivering power for up to 16 hours a day, with panels handling daylight generation and batteries managing evening demand.
Tesla's power purchase agreement, announced by ContourGlobal in July, secures approximately 1 terawatt-hour of electricity annually. This long-term contract allows Tesla to access a significant amount of clean power without needing to build or operate the generation facility itself. Under the agreement, Tesla will also receive the renewable energy certificates associated with the power, which allow the company to count the electricity as clean. While the specific Tesla sites that will utilize this power, the payment terms, and the contract duration have not been disclosed by ContourGlobal, a trade publication reported in July that the power is intended for Tesla’s California operations.
The Sterling facility is designed to connect to lines managed by the Western Area Power Administration, a federal agency distributing power from sources such as Hoover Dam. The project has established firm rights to transmit power over these lines into California and will be "pseudo-tied" to California’s grid. This arrangement allows California’s grid operator to integrate Sterling as if it were a plant within its own territory.
The battery system at Project Sterling has a rating of 360 megawatts and 1.4 gigawatt-hours. These lithium iron phosphate (LFP) batteries feature liquid cooling and built-in fire protection, offering a safer alternative compared to other battery chemistries, according to the source material. The system is capable of running at full capacity for approximately four hours. This battery capacity, combined with daily sunshine, is what enables the project to achieve its target of up to 16 hours of continuous power delivery. The panel rating for the facility is 509 megawatts of direct current, with the plant capable of sending 450 megawatts of alternating current to the grid after inversion. Each of the more than 760,000 panels is estimated to produce around 670 watts. Neither the battery supplier nor the panel manufacturer has been identified.
ContourGlobal acquired Project Sterling during its development phase and subsequently reconfigured it to meet Tesla's specific requirements, effectively making it a made-to-order power plant. The early start to construction through "off-site physical work of significant nature" may relate to criteria for claiming federal tax credits for solar projects, though ContourGlobal has not confirmed this. The development of Polaris Road, a new 5.2-mile road, is also underway to connect points within the project site.
