Imergy announced this week that SunEdison agreed to purchase up to 1,000 flow batteries from Imergy for rural India applications.

Total energy of the deal was reported as up to 100 MWh, so this is 100 kWh per flow battery. Imergy makes a 30 kW and a 5 kW unit. A 30 kW ESP30 running for 3.3 hours is an awfully short runtime, so it’s more likely that these are small ESP5 5 kW units that can run for 20 hours to back up India’s notoriously unreliable grid. [Edit: see below for clarification from Imergy]

(Flow batteries make sense for long runtime applications, since increasing energy is simply a matter of adding more liquid electrolyte, rather than more cells. A 5 kW system has much cheaper cells, power electronics, and overall capital cost than a 30 kW unit)

Imergy has been heavily recruiting since its pivot to vanadium and name change from Deeya to Imergy.

This announcement is a great step forward for energy storage. Keep an eye on how the deal matures and how successful the deployment is. Can we see some economic and price data?

Edit March 26: Imergy tweeted to clarify that these will be higher-power units: “The products will be in the 120kWh range sized to meet load requirements between 15kW(10hrs run time) to 25kW(7hrs run time)”

@BruceLinEnergy The products will be in the 120kWh range sized to meet load requirements between 15kW(10hrs run time) to 25kW(7hrs run time)

— Imergy Power Systems (@Imergy) March 26, 2015