The energy storage system producer raised $30m in a round co-led by SoftBank subsidiary SB Energy that also featured PTT Global, Evergy and BASF.

SB Energy, a renewable energy-focused subsidiary of telecommunications and internet conglomerate SoftBank, co-led a $30m series C round for US-based energy storage system provider ESS on Monday.

The round was co-led by energy investment fund Breakthrough Energy Ventures and included chemical producers PTT Global and BASF, the latter through its BASF Venture Capital unit, as well as Evergy Ventures, an affiliate of energy utility Evergy.

Cycle Capital Management, Presidio Partners Investment Management, IPM Group and Pangaea Ventures filled out the round.

ESS produces grid-scale energy storage systems for use with renewable energy sources like wind or solar. They rely on iron-flow batteries, which ESS claims are sustainable and contain no hazardous waste.

The company plans to use a portion of the series C funds to expand manufacturing of the second iteration of the battery as it expands into the provision of utility-scale systems for use with larger energy installations.

Craig Evans, founder and chief executive of ESS, said: “This investment reinforces the value and growth potential of our long-duration flow battery solution. It enables us to scale up manufacturing to meet our order pipeline, as well as continue to pursue global deployment opportunities.”

Pangaea Ventures led the company’s $3.2m seed round in 2015 before returning for a $13m series B in late 2017 that was led by BASF Venture Capital and backed by Cycle Capital Management, Presidio Partners Investment Management and IPM (then known as InfraPartners Management).

Photo courtesy of ESS, Inc.