Arizona Public Service (APS) is the largest electric utility in Arizona, United States. Since 1985, it has been the principal subsidiary of publicly traded S&P 500 member Pinnacle West Capital Corporation, known as AZP Group until 1987. Pinnacle West Capital made a profit of $500 million in 2017. With 4,000 MW of generating capacity, APS serves more than one million customers in 11 counties throughout most of the state, but mainly concentrated in northern and central Arizona. APS is one of the two major suppliers of electricity to the Phoenix metropolitan area (the other being Salt River Project (SRP)). APS is regulated by the Arizona Corporation Commission (ACC), the state agency that, by mandate of Article 15, Section 2 of the state's constitution, regulates energy utilities in Arizona, with the notable exception of SRP, the rural electrical districts, and the City of Mesa electric utility serving Downtown Mesa and the immediate vicinity (with the rest of the city being served by SRP). The holding company, Pinnacle West Capital, through its APS utility sells wholesale and retail power to the wider western United States and also provides energy-related services. Through another major subsidiary, Pinnacle West also developed and managed real estate in Arizona. Pinnacle West left the real estate business in 2010. The utility company also operates three nuclear reactors. Its Palo Verde Nuclear Generating Station in Arizona, the largest nuclear plant in the U.S., came under scrutiny by the Nuclear Regulatory Commission in 2005 when operational problems began to cause prolonged outages. From Wikipedia
