California ISO The California Independent System Operator (CAISO) is a non-profit public benefit corporation charged with operating the majority of California’s high-voltage wholesale power grid. Balancing the demand for electricity with an equal supply of megawatts, the ISO is the impartial link between power plants and the utilities that serve more than 30 million consumers. The ISO provides equal access tot eh grid for all qualified users and strategically plans for the transmission needs of this vital infrastructure.