... that for decades now we have rather smart schemes to keep the beam aligned that are so dead simple they don't need computers. You can do that with simple electronics and a pilot "beam" going upwards from your target. So that's kinda the part of the whole idea that works best.
It's still a fairly bonkers idea, as you can just place solar panels on the surface of the planet... and you can more than overcompensate the atmospheric losses by just putting on more cells... and storage... for a fraction of the price it costs to send those panels up there. Those plans are like Gadget-Bahns, trying to steer politicians away from doing sensible things right now for lofty goals in the future.
So yes, this is a bonkers idea that keeps popping up every decade or so for the last few decades. So many of the detail problems have been solved for decades. The main problem, that it's extremely expensive, however remains.
BTW to show you how old the idea is, it was a background set piece in the story "Reason" by "Isaac Asimov" from April 1941.