• space solar panel power per weight: 100W/kg (vs. 10W/kg for rooftop ones)
  
• solar panel price: $4.3/W [I'll be generous by using this for the space-based, too]
  
• future launch costs to GEO: $10,000/kg (generous)
  
• capacity factor on California rooftops: 20%
  
• capacity factor in GEO: 99%
  

So,

1. electricity from the rooftop solar: $4.3/(175320h * 0.2 * 0.001kW) = 12.3 cents/kWh;
   
2. electricity from the space-based solar: ($10,000/100 + $4.3)/(175320h * 0.99 * 0.001kW) = 60.1 cents/kWh.

Why? In addition, whay if it could produce in a larger volume for rooftops?

:: :: :: :: ::

There is of course another problem with space-based solar power stations in general: the microwave downlink could be used as a weapon... or cause deadly accidents.

_{*Lunatic*, n.
One whose delusions are out of fashion.}