Sun to electric power conversion is ~15-25% efficient.
Microwave power transmission is up to 50% efficient.
Satellite power provides power 24/7 and does not need any form of energy storage, and would be a full replacement for traditional base-load power generation (like hydro, nuclear and coal).
Solar power is limited to roughly 8 hours a day, and needs either energy storage or other base-load generation. Power storage is either inefficient or costly.
The only relevant question is if it is possible to make it cheap enough, without the pie-in-the-sky Skylon.
What would it cost with Falcon-9 or Falcon-Heavy as launch vehicle for the satellites?