I hope this is more education even dealing with IOU's like the Tesla Power Wall. Read the Seven Modes of Operation on Page 7
https://library.e.abb.com/public/3c4e15816e4a7bf1c12578d100500565/Case_Note_BESS_GVEA_Fairbanks-web.pdf
Schedule Load Increase, Power System Stabilizer, Spinning Reserve are very import in control of the power system. Early days of electric generation was built for businesses that often only needed electric during specific hours of the day, during off Peak hours, power would turned ON to residential area. Demand for electric 24 hours a day meant increased Generation and Control. Then came with the Electric Clock, so keeping the electric clock reading the same as the wind-up wall clock, time also had to sold. Thus regulating was more difficult with governors used with slow response. The aim was to have the correct at least once a day sometime, mostly after mid-night and 6AM In 1950's, 60's, most electric utilities, in the lower 48 states connected together. Time became more important to maintain Grid integrity. That called faster generator governors, faster responding generators and necessary option was (and still is ) Automatic Customer Load Shedding.
Lots stories can be told here and may many will be remember the NYC blackouts or Earth quakes problems. How many remember the Vertical Roll on the display of the TV, it wasn't the TV's fault
I personally have not read capability or sizing of the Tesla Wall Unit but did see a picture of fenced area contain 50 units or more units. For comparison, Texas would need about 50 of the Alaska Battery Energy storage units.
My work history has mostly Electric Utility in the Western and Eastern sections but not the Texas section. El Paso TX is part of the western area.
Clay