Largest US Solar Storage Officially Opens


The largest solar-plus storage project in the U.S., the Edwards and Sanborn Solar + Energy Storage project, is now open and operating, according to renewable energy provider Terra-Gen and construction development company Mortenson.

According to a release from Mortenson, the new project in California covers 4,600 acres and includes over 1.9 million First Solar modules to provide power to the city of San Jose, as well as Southern California Edison, Pacific Gas & Electric Co., the Clean Power Alliance, and more.

Project Details

The release states that the solar panels can hold a total of 875 Mega Watts defined conditions (MWdc) solar, and almost 3.3 Giga Watt hours (GWh) of energy storage. It also reportedly has a 1.3 GW interconnection capacity.

Through this project, California’s grid is expected to get enough electricity to run the equivalent of about 238,000 homes, leading to an estimated 320,000 tons of carbon dioxide emissions abated each year.

The release adds that energy storage consists of LG Chem, Samsung and BYD batteries. This reportedly required 98 miles of MV Wire, over 361 miles of DC wiring and 120,720 batteries.

“Now fully operational, this facility is a transformational project in the industry and is providing resiliency to the grid,” Vice President of engineering at Terra-Gen Brian Gorda said.

“The Mortenson team was tasked with an extremely difficult goal to build this project, and they proved to be the right partner for the job. We are excited to bring Edwards & Sanborn online and benefitting the people of California.”

Part of the project is located on the Edwards Air Force Base in Kern County, California, and is now the largest public-private collaboration in U.S. Department of Defense history.

Over 1,000 craftworkers reportedly contributed to the project and produced strong safety results, including over one million hours injury-free and a safety award from the California Association of General Contractors.

“Only in America can we take barren land, embrace the power of the sun, and create an engineering marvel,” Brigadier General William Kale, Air Force civil engineer center commander, told PV Magazine.

“So, take the time to reflect, see the great work that was done, and understand the significance of this project and what it can lead to. Hopefully, this is just the spark.”

“Mortenson is honored to help Terra-Gen deliver the Edwards & Sanborn project and provide the region with clean, resilient power” said Mark Donahue, Senior Vice President at Mortenson. “I’m proud of the world-class facility our team designed, built and commissioned for Terra-Gen."

Project Background

The project was first announced in 2020, when Mortenson released a statement outlining the agreement with Terra-Gen to proceed with construction.

“Selecting the right partner to execute a project of this scale coupled with cutting edge battery experience was paramount for Terra-Gen, and Mortenson was a natural fit,” said Gorda at the time. “Terra-Gen is excited to push the industry to new heights and build a plant that provides energy for all hours of demand.”

Mortenson also announced then that it wouldbe the full Engineering, Procurement, and Construction (EPC) contractor on both the solar and energy storage scopes. Site construction was expected to begin in Q1 2021 and had previously been expected to reach completion in Q4 2022.

“We are proud to combine our solar and energy storage design and construction expertise with Terra-Gen’s development capabilities to deliver a world-class energy facility,” said Trent Mostaert, Mortenson’s vice president and general manager of Solar.

PV Magazine added that the first phase of the project added 346 MWac of solar modules and 1.5 GWh of battery storage. Financing for that phase closed in 2021 and included $804 million senior secured credit facilities.

This reportedly included $400 million construction and term loan facility, a $328 million tax equity bridge facility, as well as a $76 million construction and revolving letter of credit facility.

J.P. Morgan was expected to provide the tax equity commitment for the initial phase of the project, with Deutsche Bank in charge of the construction and term financing.

Additionally, in 2022, Terra-Gen closed around $1 billion in project financing for the second phase of the project, which included $460 million construction and term loan facility, $96 million construction and revolving credit facility.

This had also included a $403 million tax equity bridge facility. BNP Paribas, CoBank, U.S. Bank, ING and Nomura led the funding. In total, the two financing rounds for the project reportedly totaled over $1.7 billion.

In February 2023, Mortenson unveiled the Edwards Solar project at a ribbon cutting ceremony.

The Edwards facility, which is one part of the Edwards & Sanborn Solar + Storage project, was reported at the time to have almost two million solar panels installed and 120,000+ batteries installed at completion.

“Projects like [Edwards & Sanborn] are modern marvels in engineering, construction, cooperation, and collaboration. It takes a commitment from each party to make it all possible, but today I would especially like to acknowledge the men and women in the field whose minds and muscle designed, procured, and built this facility,” said Dan Johnson, CEO of Mortenson.


Tagged categories: Construction; Department of Defense (DOD); Energy efficiency; Environmental Control; Environmental Controls; Environmental Protection; Government; Green Infrastructure; Infrastructure; Infrastructure; Jobs; NA; Net Zero Energy ; North America; Program/Project Management; Solar; Solar energy; U.S. Air Force

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