Alec Cameron said the following to MIKE ROSS on the subject of
solar power in apt? (18 Nov 97  06:22:16)
 AC> On (16 Nov 97) MIKE ROSS wrote to Alec Cameron...
 AC> ================
 AC> re this bit of rough math-
 AC> what is "lost" is 0.7 of the 30 volts available on open cct. .7 div
 MR> by
 AC> 30 =   2.33%. Less than a wee cloud passing by.
 AC> ================
The diode voltage does make little difference I agree. It was just the
actual value I didn't find right because it neglected ohmic losses. Like
you said it was just a value out of thin air. Nothing wrong with that.
 AC> My point is that with panels driving batteries, maximum efficiency is
 AC> NOT the proper goal. Maximum energy into the battery is what we want,
I think the math to find the optimum load would look like this:
                          /--------------------------
Rload = E^2   - Rs +/-   / (E^2/Po - 2Rs)^2 - 4Rs^2
       ------           / ---------------------------
        2xPo          \/               2
where E is the cell emf.
      Po is the rated cell output power
      Rs is the diode's apparent resistance at rated current (Vf/If)
      Rload is the optimal load for maximum power transfer
      +/- is real or imaginary roots
Just punch the formula into the old 4 banger and let it rip.
Have fun!
 Mike
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