From: Impedance@UgotOCD.invalid   
      
   My experiences totally disagree with your 80%.   
      
   Some caveats   
   - Now I am using a MPPT circuit but my panels put out 100% of rating in   
   spring and fall. Less in summer (see below)   
   - In the summer I have my panels at too steep of an angle temporarily but it   
   keeps most of the snow off them.   
   - In the winter my panels put out 125% of their ratings due to higher   
   efficiencies in the cold, and they are still too steep an angle for the sun   
   at solar noon.   
   - Cheaper panel manufacturers may "cheat" at their ratings agreeing with   
   vaughn's statements.   
   - These ratings are into a 48 vdc battery bank charging at 56 vdc and ~70   
   vdc panels at MPP.   
      
   Battery losses are agreed and more.   
      
   This project may be fun and experimental as a hobby but in view of *easy*   
   grid power a total waste of money. At this battery development stage date   
   batteries always cost more than the any energy saved from grid energy costs,   
   forever.   
      
   Note: Grid energy costs may include digging a trench, remote switching and   
   wiring, inspection and many other costs.   
   LED costs would be constant. I have many LEDs that have not lasted more than   
   two-three years in outdoor sunlight and Christmas tree strings. The light   
   produced is slightly cheaper than equivalent incandescents and they   
   typically last longer but the costs still outweigh savings over other   
   technologies.   
      
   ---------   
   "vaughn"  wrote in message news:jen6qp$kvc$1@dont-email.me...   
   In the real-world, expect about half of the advertised panel output. Why?   
   That   
   "50 watts" only happens with a perfectly matched load, in full sunlight, and   
   with the panel tracking a perfectly full sun. You won't have a sun tracker   
   (derate) and at that price-point you won't have an MPPT charge controller   
   (derate). Also, your battery only gives back about 80% of what you put into   
   it   
   (derate).   
   Still, from my own experience, I think that panel will likely do the job you   
   describe.   
   Vaughn   
   -------------------   
   "danny burstein"  wrote in message   
   news:jen24b$9r9$1@reader1.panix.com...   
   > Assuming they're telling the truth and this panel would   
   > provide 50 watts in direct sun, that would (rule of thumb)   
   > get us about 200 watt-hours on sunny days, and maybe   
   > a quarter of that on a typical foggy/misty one.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)