Secondary usage as an impromptu death ray is the only way that pencils out for me. Even if you could cut the receiving area to 1/10 the equivalent solar panel area, the economics of launching a huge space array seem really difficult to ever make economic sense vs fully land based system.
Microwaves don't absorb uniformly into materials. You can have a potentially deadly amount of energy, but if you can't actually interact with it then it's harmless.
The proposal for rectenna arrays was grids over farmland which could be used for cattle grazing with illeffects to the cattle - simply not enough EM can be absorbed by them for it to matter.
