It’s not efficient for replacing power sources on the ground, but for airplanes, ships, and remote communities it could be genius. No need to carry heavy batteries around and your capacity is virtually unlimited (At least as far as it is feasible to build a massive orbital solar array).
Why isn't it efficient for replacing ground based power sources? In the case of replacing ground based solar, it means not having to deal with intermittency and diplacement of natural habitats. In the case of hydrocarbon-based power plants, it means not having to contend with pollution.
