This is how it typically goes with solar arrays: We build them on open space rather than in developed areas. That is, they overwhelmingly occupy croplands, arid lands and grasslands, not rooftops or parking lots, according to a global inventory published last month in Nature. In the United States, for instance, roughly 51 percent of utility-scale solar facilities are in deserts; 33 percent are on croplands; and 10 percent are in grasslands and forests. Just 2.5 percent of U.S. solar power comes from urban areas…

A typical Walmart supercenter, for instance, has a five-acre parking lot, and it’s a wasteland, especially if you have to sweat your way across it under an asphalt-bubbling sun. Put a canopy over it, though, and it could support a three-megawatt solar array, according to a recent study co-authored by Joshua Pearce of Western University in Ontario.