FT: How to make space-based solar power a reality
ft.com
ft.com
I looked it up and they are proposing a 2000 tonne satellite at geostationary orbit. That's already over $20bn just in launch costs even with SpaceX.
Or if use some not existent now very cheap system to deliver payloads, like catapults or centrifugal accelerators.
If make all at Earth and deliver by rockets, economy will be somewhere like build solar power station in Antarctica.