Elon Musk shows himself to rather out of touch with science. He is using his money to make a name for himself by driving forward with some outlandish plans. He is an embarrassment to his own employees sometimes when he quotes pseudo-scientific ideas that have been obsolete for decades. (One of these was the idea of using nuclear explosions to make Mars inhabitable.)
But his optimism to get employees to "make it happen" will drive some scientific progress in spite of himself. Even here, however, he has often just attached his name to some idea that came out of Japan or China or some US or European scientific think tank that was never associated with Musk. He attaches his own unrealistic timelines to these ideas, however, and then begins to lose credibility.
This particular idea has some merit, but there is a lot more expense in creating the infrastructure than people realize. There is the mining of the elements that go into solar cells, the manufacture of solar panels, the trucking of materials to such a solar hub, the infrastructure to build out the lines from the hub across the USA. Currently these types of expenses reduce the ROI value of this particular type of renewable energy so much that it makes carbon (coal/oil/petroleum) seem much more desirable for generating power, and for which an infrastructure is already in place.
When viable, I would like to see how close to Hoover Dam this could be built to re-use some power lines that emanate from there, and already reach to many southwest states. Perhaps an even better idea would be to find a place near Yuma or Mexicali, so that half of the power would be used to desalinate water for Mexico and the US by piping saltwater from the Gulf of California, then freshwater piped elsewhere with a mountain or salt and minerals as a byproduct.
The same Elon Musk whose red sports car sent to Mars was supposed to have batteries for cameras and telemetry that would last 12 hours and more.
They failed at four hours.