The Eleven Mile Solar Center is a utility-scale renewable energy project located in Arizona, the US. The project was developed by Denmark-based energy company Ørsted.
Eleven Mile includes a 300MW solar photovoltaic (PV) plant with a 300MW/ 1,200 megawatt-hour (MWh) battery energy storage system (BESS). The project is the largest co-located solar and storage centre on local electrical utility Salt River Project’s (SRP’s) power grid.
The construction works on the renewable project commenced in January 2023. Ørsted announced the start of commercial operations at the Eleven Mile Solar Center in September 2024. The project can produce enough electricity to power around 65,000 homes.
At peak, the project created more than 1,000 jobs.
Eleven Mile Solar Center Ownership
Initially, the project was owned by Ørsted.
In December 2024, Ørsted completed the divestment of a 50% equity interest in the Eleven Mile Solar Center to Energy Capital Partners (ECP), a private equity firm that focuses on investing in infrastructure and energy transition assets.
The transaction, which included two other assets in Texas, was valued at $572m. Ørsted retains the remaining 50% in Eleven Mile Solar Center, and it will continue to operate the project over its lifespan.
The company had raised a total of $734m in upfront proceeds for these projects from tax equity partner JP Morgan.
Location and Site Details
The Eleven Mile Solar Center is located in Pinal County, Arizona, near the city of Coolidge. The site includes more than 2,000 acres of land in an area selected for its solar irradiance levels, access to transmission infrastructure, and proximity to large energy consumers.
According to Ørsted’s public consultation materials, over its nearly 30 years of operational life, Eleven Mile Solar Center is expected to contribute over $80m in property taxes to Pinal County and other local jurisdictions.
Eleven Mile Solar Center Infrastructure
Eleven Mile Solar Center features around 857,000 solar panels. The solar component of the project consists of PV modules mounted on single-axis trackers, allowing the panels to follow the sun’s path during the day for improved efficiency.
The battery storage system provides four hours of energy storage capacity, enabling the project to store solar power generated during the day and release it to the grid during periods of high demand, such as in the evening.
The BESS features around 2,000 battery cubes. Each BESS cube resembles a shipping container and stores power, which is critical in maintaining grid stability.
The battery technology supports grid reliability by providing load shifting, frequency regulation, and ancillary services.
Grid Connection
The Eleven Mile Solar Center is connected to the Pinal Central Substation through a 235-kilovolt (kV) transmission line. The transmission infrastructure includes both above-ground and underground segments. According to documents shared by Ørsted during community outreach, the total length of the new transmission line is approximately a quarter of a mile, with routing designed to reduce visual impact and avoid sensitive areas.
The project is located within the service territory of the SRP, a public power utility serving the Phoenix metropolitan area. SRP facilitates the grid integration of the project’s output and has worked with Ørsted to support the delivery of renewable energy to corporate and institutional buyers.
Power Offtake Agreement
A significant portion of the power generated by the Eleven Mile Solar Center will be delivered to Meta’s planned data centre in Mesa, Arizona. Meta announced in December 2023 that it had partnered with SRP and Ørsted to source renewable energy for the facility. The partnership supports Meta’s commitment to operating on 100% renewable energy and achieving net zero emissions across its value chain.
Excess power generated by the Eleven Mile Solar Center is delivered to the Salt River Project’s broader grid.
Contractors Involved
First Solar supplied the photovoltaic modules for the solar farm, while Nextracker delivered the solar tracking equipment.
The BESS was supplied by Fluence, a US-based energy storage technology and services provider. SolarCycle, a technology-based solar recycling company, is responsible for processing and recycling of end-of-life solar modules.
Ørsted also hired local subcontractors and suppliers during various phases of development.
