Understanding the ISO 
The California Independent System Operator Corporation (ISO) manages the flow of electricity across the high-voltage, long-distance power lines that make up 80 percent of California's power grid. The nonprofit public benefit corporation safeguards the economy and well-being of 30 million Californians by "keeping the lights on" 24/7.
As the impartial grid operator, the ISO opens access to the wholesale power market that is designed to diversify resources and lower prices. It also grants equal access to 25,865 circuit-miles of power lines and reduces barriers to diverse resources competing to bring power to customers.
Every five minutes the ISO forecasts electrical demand, accounts for operating reserves and dispatches the lowest cost power plant unit to meet demand while ensuring enough transmission capacity is available to deliver the power.
The ISO opened its northern and southern California control centers in 1998 when the state restructured its wholesale electricity industry. While utilities still own transmission assets, the ISO acts as a traffic controller by routing electrons, maximizing the use of the transmission system and its generation resources, and supervising maintenance of the lines. As the nerve center for the California power grid, the ISO matches buyers and sellers of electricity, facilitating nearly 30,000 market transactions every day to ensure enough power is on hand to meet demand.