Plus find an application to get around the fact that ground-based solar is always going to be cheaper and more reliable than space-based solar. At best, you get an order of magnitude increase in electricity output when you put your collectors in space (no night, no clouds, no atmospheric attenuation, increased efficiency from being able to radiate heat to deep space at ~4K). Even with space elevators, it will be almost certainly less expensive to install collectors on ten square kilometers of desert than to install a square kilometer of collectors in orbit. From a risk management perspective, it's also better to have a local, scalable, easily-fixed array than a far-off one dependent on the continuous function and alignment of a laser/maser.

Note: I work for a company that makes PV panels for ground-based solar farms, so I have a bit of a bias.

Military applications seem like a good excuse for space-based solar power. You could quickly provide power to forces on the ground or at sea. It'd also be good for constant-thrust interplanetary travel - a VASMIR unit powered by beamed power would be far more effective than one powered by solar panels or a heavy nuclear reactor.