Sun Streams 3 Solar

Arlington, Ariz.

Award of Merit

Submitted by: McCarthy Building Cos.

Owner: Longroad Energy

EPC Contractor: McCarthy Building Cos.

Civil Consultant: EVS Inc.

Structural Consultant: DLR Group Inc.

Electrical Consultant: McCalmont Engineering


Longroad Energy’s first battery energy storage system (BESS) at its Sun Streams complex sits about 40 miles west of Phoenix. The AC-Coupled 215 MW/860-MWh BESS is paired with a 215-MW solar facility, which generates enough power for 90,000 homes while abating 200,000 metric tons of carbon dioxide emissions.

The BESS component of Sun Streams 3 stores excess energy created by the solar facility and releases it to the grid during peak hours. It features 1,596 Powin Centipede energy segments, more than 1 million battery cells, 84 inverters and 84 collection segments.

Before construction began, the contractor modeled the entire site in Revit to identify areas that would be best suited for prefabrication. This effort enabled the team to install approximately 90% of the grading, structural and electrical elements in less than six months.

The contractor also created dedicated prefabrication yards for combiner boxes and underground conduit racks on site, resulting in gains of more than $150,000.

Given Maricopa County’s strict drainage and grading requirements, the project leadership team worked closely with the planning department during the permitting stage to minimize plan review timelines.

Also, with the design and approval of a drainage waiver on the property, the team saved more than $1 million in costs.

Sun Streams 3 was delivered under budget and on schedule in May 2024.