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ESS Inc signs 2GWh iron flow battery deal with Softbank’s SB Energy

An ESS Inc Energy Warehouse being lowered into place. Image: ESS Inc via Twitter.

A framework agreement for the deployment of 2GWh of iron electrolyte flow batteries has been signed between manufacturer ESS Inc and SB Energy, the clean energy arm of Japanese telecoms giant Softbank. 

SB Energy will use the long-duration battery energy storage systems (BESS) at utility-scale solar projects that it has under development in the US, in Texas and California. ESS Inc said the first order in the 2GWh deal, which runs to 2026, has already been delivered to an SB Energy project site in California, for commissioning during October. 

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The agreement appears to mark a significant step up for the Oregon-headquartered long-duration battery storage company, which was founded in 2011. It also appears to be the biggest flow battery deal of any kind seen so far. 

After years of lab development and pilot deployments, ESS Inc has been working more recently to turn its unique, proprietary technology offering into a commercial offering and towards the beginning of this year launched a grid-scale product based on its iron and saltwater electrolyte battery chemistry.  

The non-toxic, non-degrading battery chemistry is designed to be environmentally sustainable and last many years in the field. It is configurable to offer from four hours up to 12 hours of storage and ESS Inc said that in addition to using abundant materials, it is low-cost. 

In 2019, former CEO and co-founder Craig Evans told this site that the batteries can “cycle tens of thousands of times,” and do so with “zero capacity fade”. Evans was speaking then on the occasion of a US$30 million Series C funding round closing, with SB Energy among investors participating. Other investors in the company have included the Bill Gates-founded Breakthrough Energy Ventures. 

SB Energy: ‘US-made clean energy technology aligns with Biden policy aims’

While the specific projects SB Energy intends to equip with the iron flow batteries have not been revealed in a press release issued yesterday, it did point out that the developer owns 1.7GW of solar PV capacity across five utility-scale projects in Texas and California, already in operation or under construction. It has a further multi-gigawatt pipeline of solar and storage projects in development in the US for execution in the next few years. 

“ESS’s unique ability to manufacture and ship batteries using iron, salt, and water is a game-changer, enabling SB Energy to offer our customers safe, sustainable and low-cost energy storage today,” SB Energy’s co-chief executive officer Rich Hossfeld said. 

“Long-duration storage is absolutely critical to providing flexible, affordable renewable energy at scale and aligns perfectly with the Biden administration’s ambitious clean energy initiatives,” Hossfeld, who is also an ESS Inc board member, added, while also highlighting that ESS Inc will be capable of manufacturing its battery systems in the US. 

ESS Inc claimed an industry first in 2019 by launching a 10-year battery insurance plan through Munich Re which covered its Energy Warehouse 50kW-70kW / 400kWh-600kWh product but has since been expanded to include the 3MW Energy Center product.  

The company is currently targeting a listing on the New York Stock Exchange (NYSE) through combination with special purpose acquisition company (SPAC) ACON 2 Acquisition Corp. The deal will value the combined company at just over a billion dollars and will release around US$465 million in net proceeds. 

ACON 2 shareholders are set to vote on the merger in the next few days.  

In terms of other recent deployments, reported just a few days ago that 17 Energy Warehouse systems totalling 8.5MWh are being sold to Enel Green Power España for installation across solar farms in Spain. Again, ESS Inc has said that that deal is for a wider engagement with Enel Green Power across various European Union territories. 

“The energy transition will require massive amounts of storage capacity in the coming years and we are focused on scaling up our manufacturing capacity to help meet that demand,” ESS Inc CEO Eric Dresselhuys said. 

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