Sounds like a local outfit here in PA bought a system. The local paper has some pictures and numbers:
The iron-flow battery will allow a Chester County company to use its solar power at night and may help mitigate the climate crisis.
www.inquirer.com
A 400 kWh capacity 'Energy Warehouse' system costs 'about $200,000', or about $500/kWh. This is reasonable for a new tech system (not cell) cost, given its projected long service and cycle life.
For comparison, a much smaller 13.5 kWh Tesla Power wall is $11k MSRP and about $8.5k after rebates. This is about 50% higher per kWh than the ESS system. The price per kWh drops somewhat for higher capacity systems. Both Tesla and ESS appear to have a 10 year warranty (suggesting similar 20k cycle lives)
The EW system lives in 40' shipping container, with a dry (no electrolyte) mass of 20 tons. The electrolyte weighs another 19 tons. So that works out to about 10 kWh per ton, or 100 kg per kWh. This is more than 2X the weight of a lead-acid system (that has much poorer cycle and service life).
The question here is ESS's margins. It seems likely that their price point for the above system is set to compete with lithium systems and get units out the door and into the field. I would bet that at low production volume, they will struggle to make a profit. The production scale where they do make a profit is unknowable. The new 10% rebate from the IRA could be helpful. The price surge in lithium battery minerals will probably help them MORE.
What I liked from their website is that their 'second generation' cells delete all the O-ring seals and half of the plumbing fittings of the Gen 1. Yeah, 40 tons of cells held together with O-rings and (presumed off the shelf) plumbing fittings sounds like a prototype. They also have a robotized cell manufacturing system. This will be important for price reduction at scale.
Good luck to them!