Coal-fired plants supply roughly two-fifths of Arizona’s demand for electricity. Natural gas-fired plants and nuclear power supply most of the remainder. Arizona’s sole nuclear power plant, the 3-unit Palo Verde plant, provides about one-fourth of the State’s total electricity generation. Palo Verde is the Nation’s largest nuclear plant and has the second-highest rated capacity of any power plant in the United States. The Glen Canyon and Hoover Dams, both located on the Colorado River in northern Arizona, provide hydroelectric power. Although Arizona leads the Nation in solar power potential, its solar-powered generation facilities are small and the State has not yet developed its solar resource on a large scale. More than one-half of Arizona households rely on electricity as their primary energy source for home heating.
http://tonto.eia.doe.gov/state/state_energy_profiles.cfm?sid=AZ
http://www.eia.doe.gov/cneaf/electricity/st_profiles/arizona.html
http://www.eia.doe.gov/cneaf/nuclear/page/at_a_glance/states/statesaz.html