Texas: SolarMax wins EPC contract for 600 MWh BESS; Spearmint nets investment for 400 MWh of BESS

SolarMax has been awarded an engineering, procurement and construction (EPC) contract for a 600 MWh BESS in Corpus Christi, Texas. Under the contract’s terms, SolarMax will deliver full-scope EPC services for the BESS and its interconnection infrastructure for Navboot Holdco, LLC.

SolarMax’s CEO, David Hsu, said the EPC award underscores the acceleration of the company’s utility-scale project portfolio.

“In less than a year, we have progressed from entering the Texas market to securing three additional large-scale battery storage contracts, demonstrating our ability to compete at the highest levels of the US energy infrastructure market.”

“Projects of this scale are central to our long-term growth strategy,” Hsu added. “This 600 MWh system not only expands our contracted backlog materially, but also reinforces our positioning as a trusted EPC partner in delivering critical infrastructure to support grid stability, energy affordability, and long-term shareholder value.”

The Californian company expects the contract to generate revenues of approximately $258.1 million.

As well as the Texas BESS, SolarMax has also announced in recent days it entered into two agreements for two separate utility-scale batteries in Puerto Rico, with a combined storage capacity of 400MWh. It will provide full-scope EPC services similar to the Texas BESS, with design, engineering, procurement, installation, construction, testing, startup, and commissioning all included.

ERCOT expansion

Meanwhile, in the Texas cities Del Rio and Laredo, Spearmint Energy has secured investment for 400 MWh of BESS across two projects. The investment concerns Tierra Seca and Seven Flags, both 100 MW/200 MWh systems to be added to the ERCOT grid.

The Miami-headquartered BESS developer closed an equity investment in the projects from Kyuden International Corporation, the multinational arm of Kyuden Group, a large energy utility in Japan. This marks Kyuden’s first investment in US BESS.

“We believe Kyuden International’s significant investment in Tierra Seca and Seven Flags underscores their confidence in Spearmint’s ability to safely and efficiently bring projects online that enhance grid stability and meet the needs of communities across ERCOT,” said Andrew Waranch, Founder, President, and CEO of Spearmint.

Spearmint Energy previously secured more than $250 million financing from Manulife, East West Bank, Investec, and Sugar Creek Capital in 2025 to support the construction of Tierra Sec and Seven Flags. Both projects commenced construction in late December 2025, and both use Sungrow’s PowerTitan 2.0 energy storage platform following the signing of a Texas BESS-focused collaboration agreement between the two companies in 2024.

Spearmint’s project development pipeline comprises 23 projects totaling over 15 GWh of storage capacity. It already operates the 150 MW/300 MWh Revolution BESS in West Texas.

Finally, construction is underway on Energy Vault’s 150 MW/300 MWh BESS in Madison County, Texas. The SOSA Energy Center BESS is expected to reach commercial operation in 2027, and Energy Vault will oversee the long-term operations as well the initial EPC phase.

The BESS will use Energy Vault’s B-VAULT DC product, which the company acquired from Savion, a subsidiary of Shell. It is expected to generate approximately $350 million in total revenue over its technical life, with annual recurring revenues expected between $17 million and $20 million.

Energy Vault has deployed 1.4 GWh of storage capacity since 2023, and it has projects in China, the US, Italy, Australia, and entered the Swiss market in December 2025. Its other ERCOT grid BESS projects include the 200 MWh St. Gall Battery and the 114 MWh Cross Trails project.