Innovation amid a raucous rooftop solar squabble

The explosive expansion of U.S. residential rooftop solar installations- which increased by 51 percent last year???threatens utilities??? traditional role as electricity suppliers. The resulting backlash has been most intense in sun-bleached Arizona, which is second only to California in installed solar capacity. The battle has the potential to blunt the state´s solar growth, but there are signs that it could also inspire grid-friendly technologies that expand solar´s role.