April 06, 2021 Q: What does the California Independent System Operator (CAISO) do? CAISO operates the high-voltage transmission system and the energy market for about 80% of California and a small portion of Nevada. We’re the entity that matches the real-time supply of electricity with demand and is responsible for efficiently integrating the next generation of clean energy resources into the grid. In addition to our fundamental responsibility as a primarily single-state independent system operator, increasingly we’re taking on broader functions across the western United States. Those include monitoring reliability and operating an energy imbalance market that lets us buy and sell energy with the Northwest, the Intermountain West, and the desert Southwest.