From: dietz@dls.net   
      
   Andrew Nowicki wrote:   
      
   > Solar cell weight is about 40 kg per one kilowatt   
   > of power output.   
      
   Please note that there us nothing fundamental about this figure.   
      
   Direct bandgap semiconductor materials can absorb light with   
   a thickness of perhaps 100 nanometers (the absorption length   
   of ordinary crystalline silicon is much longer.)   
      
   If the density of the material is 2 g/cm^3, and the efficiency   
   15%, and the mass/area of the plastic, etc. onto which the PV material   
   is deposited is similar, then the power density in raw sunlight   
   is about 500 kW/kg.   
      
   This concept is already assuming the use of large, very light   
   inflatable structures with significant structural strength;   
   also assuming that those structures are thin film PV collectors   
   isn't much more of a stretch.   
      
   	Paul   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)