It is hard to keep track of the movers in the world of energy storage.
I took a shot at assembling, as a list, an Energy Storage Directory, focused on technology development rather than integration, and sorted by technology. I included players that had enough capitalization and/or technology to have an impact on the market. I am not planning to list local or regional integrators.
I am sure that I missed a good number of players – it is clearly a work in progress. Let me know what you think, how it could be made better, and who I should add. I included a request form allowing listing requests at the bottom of the list.
energymag 
Alex Bistrika @bistrika has suggested RedFlow as an addition.
It;s a good pick: zinc bromide flow battery, plenty of runway $$. Their base module is 3kW/8kWh, and they have a big grant for increasing the base power. I just added them to the directory, thanks!
You may want to consider Goodwolfe (www.goodwolfe.com) world champions for battery management systems (which was the move Xtreme tried to make but failed). Mostly LiFePO4s but also supercapacitors.
I hadn’t heard of Goodwolfe, are they used in any MW+ projects? Their website appears out of date.
Side note: Xtreme Power made turnkey energy storage systems, of which the battery management system is much less than 10% of the total BOM.
Mike, thanks for Goodwolfe! I have an inquiry about about their grid-connected plans. I’ll update as soon as I get some information (right now they seem transportation/marine focused).
Pretty good start! The battery section is missing a lot of the heavy hitters in grid-scale Lithium and Lead Acid though (flow batteries are still a pretty insignificant market, however promising). Here’s some tips for additions:
Lead Acid: EnerSys, Hitachi (through recent acquisition of Shin Kobe), Exide, East Penn
Lithium Ion: Toshiba (LTO, tradename SCiB), Samsung (LMO), LG Chem (LMO), Panasonic, AESC/Nissan/4R (looking to put Leaf battery packs on the grid), SAFT, Dow Kokam, BYD, CALB, Microvast
Cody, thanks so much for all the tips! I researched them all and updated the list. A few notes:
– Ecoult is the grid face of East Penn (I think). Let me know if there is more going on there that I don’t know.
– Xalt is the new identity of Dow Kokam, and was largely purchased (at least controlling interest) by Townsend Ventures.
– Microvast: interesting company, with corporate center in Texas, everything else in China (manufacturing AND R&D).