Ran acrossed an article the other day that NREL just recently completed a (Communication-less) microgrid system that is not directly connected to the internet, but is using simple on site frequency sampling and voltage to current monitoring to react to changes on the grid for frequency control of the grid using some kind of inverter(s) that key off of grid frequency and a “bandwidth” of 59.5 to 60.5 Hertz regulation window on inverters that are “grid forming”. This sounds like a bunch of 12 or 18 pulse Variable Frequency Drives paralleled together to feed the grid transformer from a microgrid site into the grid. This article also mentioned NREL found that “microgrid controller systems” on average cost $155,000/MWh. Cut down on the overhead and O&M of complex interaction with the grid and get a much better overall LCOS for the system. Folks need to realize making smart ESS at the utility scale should not be ‘designed’ to amortize in 30 to 50 years like fueled natural gas and coal fired plants take now.