Currently, even though it pains me to say this, ERCOT has one of the most mature battery systems in the world.
Everything else is valid though.
As a fifth-generation former Texan, I understand "separatist mentality." ERCOT's buy/sell market is perhaps also the most purely capitalistic marketplace in existance (and among least-regulated, in first-world); for these reasons, winter-proofing funding is terrible and outages likely when the system is stressed (e.g. approximately every decade Texas loses power during winter storms) — which is also when generating profits are maximized (orders of magnitude increases).
Certain deregulated-market Texans are still paying off powerbills from years-old storms, a few cold days of billing often exceeding the rest of the year's usage.
plus it seems ERCOT has learned and the grid seems fine now
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