Oh yes, there is no question at all that they would make back the fuel energy cost. In money terms the fuel is a tiny fraction of launch costs (less than 1%). In fuel energy terms it costs about 400 MJ/kg to get payload into orbit via Falcon-9.
With fairly standard terrestrial designs you can get about 5 W/kg rated power (mass including support electronics), which in space would be available nearly continuously. That gives a energy payback time of about 2.5 years. With solar power designs more suited to space use, I would be very surprised if that couldn’t be reduced to weeks.
Oh yes, there is no question at all that they would make back the fuel energy cost. In money terms the fuel is a tiny fraction of launch costs (less than 1%). In fuel energy terms it costs about 400 MJ/kg to get payload into orbit via Falcon-9.
With fairly standard terrestrial designs you can get about 5 W/kg rated power (mass including support electronics), which in space would be available nearly continuously. That gives a energy payback time of about 2.5 years. With solar power designs more suited to space use, I would be very surprised if that couldn’t be reduced to weeks.