Under complete retail competition the utility has been completely removed from the supply function and is simply a transporter of electricity that provides the transmission and/or distribution infrastructure used by various market participants on an open-access basis. An Independent System Operator (ISO) or transmission system operator (TSO) is required to perform the system operations functions in an unbiased manner. Wholesale and retail marketers acquire supply from generators and sell to each other as well as to end-use customers. Generators can sell directly to customers or to a marketer. Spot markets are provided by a centralized market facilitator, either an ISO or a Power Exchange (PX).
Under this model, the regulator must create a mechanism for fulfilling the function of provider of last resort (POLR). The POLR serves customers who are unwilling or unable to contract with an electricity provider. This may be done by assigning customers to marketers on a pro-rata basis or by selecting a specific marketer to provide this service under regulated terms. As of 2020 only two U.S. states — Texas and Maine — have complete retail competition. But many countries in Europe have moved to this market model.