There's enough noonday sunlight striking the University of Arizona campus to produce 1.5 gigawatts of electricity and power all of Tucson. Sunny skies are a key reason Tucson has attracted several companies in the solar energy industry. Economic-development officials say the city is taking its place as a solar-business hot spot of the world. To spread that message, Tucson Regional Economic Opportunities Inc. [TREO] hosted several journalists last week from around the United States, including some who report for media in solar-conscious Germany.