Robert Zubrin writes about the possibility of solar power satellites in his book, "Entering Space: Creating a Spacefaring Civilization", published 1999, p. 70-74.
At the time of the writing he was very pessimistic about the feasibility primarily because of the launch weight costs. The weight to power ratio of silicon solar cells is and was about 50 W/kg. This would require 100's of billions of dollars to launch the mass for 1 gigawatt of power, about the requirements for a medium size city. And this is the mass of the solar cells alone, not the support structure or the microwave beaming system.
However, the new thin film solar cells might have 1/10,000 the areal density of silicon cells. This could conceivably bring down the costs to the 10's of millions range IF the thin film cells were at the same efficiency. However, after a web search, for the currently available thin film cells it looks like the efficiency might be only 1/100 that of silicon cells.
This will certainly improve though over time. But note that even this lower efficiency with their much lower density still leaves them within the range required for the Rudolf Meyer drive.

Bob Clark