System integrator Stem Inc has received a warning from regulators over its NYSE listing, while zinc battery technology firm Eos Energy Enterprises completed the first milestones related to private equity firm Cerberus’ investment.

The four most high-profile energy storage system (ESS) companies that listed via SPAC mergers – Eos, Energy Vault, ESS Inc and Stem – have seen their share prices fall by an average of 80% since going public.

Zinc battery firm Eos Energy Enterprises saw reduced activity in Q2 as it transitioned to its Z3 product, while CEO Joe Mastrangelo discussed its backlog, the subject of a recent short-seller note.

Zinc battery firm Eos Energy Enterprises has responded to a short seller note which saw its share price nearly halve on Thursday last week.

Solar PV paired with energy storage at scale could be provided to utilities at just US$0.10 per kilowatt hour, using advanced battery technology, one manufacturer has claimed.

Grid-scale energy storage developer Eos Energy Storage has raised proceeds of US$23 million through the initial closing of a private placement transaction and expects to use the money to increase deployment of its battery storage product.