U.S. colleges and universities are increasingly deploying solar arrays and other forms of renewable energy. Yet most institutions have a long way to go if they are to meet their goal of being carbon neutral in the coming decades.The soul of Arizona State University is Memorial Union, a hulking brick-and-glass community center that opens onto a sprawling pedestrian mall. Although the building sits at the heart of campus, its outdoor plaza was once virtually uninhabitable for four months each year, when summer temperatures in scorching Tempe often hover over 100 degrees. So in 2014, the university – Arizona’s leading energy consumer – completed construction on a PowerParasol, a 25-foot-tall shade canopy composed of 1,380 photovoltaic solar panels capable of producing 397 kilowatts of electricity.