Hard to see solar panels in space competing successfully with those same panels on the ground, considering the latter's advantages in installation cost, maintenance, transmission efficiency, and lack of problematic side effects. If a constellation of orbiting stations can provide continuous power, then a worldwide surface-solar grid could do the same, and battery technology is improving rapidly. I can't see this idea ever catching up.
1- Space based solar panels work 24 hours a day, with constant solar input and without the atmosphere muting sunlight, can be more efficient. Also, not seasonal.
2- Ground based panels are *currently* cheap because of chinese dumping (not guaranteed to continue for reasons economkc and political) and because promoters neglect to factor in the cost of batteries or alternate power source (coal or natural gas) needed for peak loads and/or night use.
3- Ground based solar (and wind) are most efficient in places other than where the energy is needed. (Unless you live in California, Texas, Hawaii, or Puerto Rico.) A massive retooling of the grid is needed to move power cross country to the north which far exceeds the cost of regional rectenna farms closer to the big cities.
4- Space based solar can use cheap giant concentrators much bigger than the panels to achieve better economics.
5- Point to point beaming involves *two* passes through atmosphere and a big orbital rectenna or three.Not that much cheaper but less efficient. (No concentrators.) Nice idea though.
6- Finally, the biggest challenger to solar (ground or space), wind, wave, and other promoted "green" energy sources is just ramping up. The first pilot plants are going online in Utah and Texas but the tech works in all 50 states. And the tech is actually cheap to deploy, works 24x7 and can be *retrofitted* to many existing thermoelectric fossil fuel plants. Look up geothermal fracking.
Space solar platforms however, will be essential not so much for beaming to earth but for the *moon". Two week "nights".
On earth, too, but only in places where tectonic issues make deep drilling inappropriate. The ring of fire, for example.