Re: PV: typical shaded V-I characteristics

[AHMChuzel@aol.com]

Tom,

If the full string of cells is uniformly shaded, the entire IV curve, for a 
typical crystalline product, shifts down (assumes current is on vertical 
scale) by roughly the same percentage as the reduction in insolation.  For 
example, if the cells are all exposed to 750 W/m^2 (25% reduction from 
"standard") of insolation then the IV curve will shift down by 25%.  The 
picture is more complicated when you have nonuniform shading and/or bypass 
diodes and/or non-crystalline products.  The IV curve may have portions that 
are shifted (out near max power, for instance) and others that are not (at 
short circuit current).  There are many variables that come into play and the 
results are sometimes surprising.

With more concrete examples, I could run some simulations for you and show 
you the IV curves.  Just drop me a line.

Regards,

Alain Chuzel
(SunCat Solar: Specialty PV Design, Manufacturing and Testing)
(602) 404-4929

In a message dated 1/18/2000 11:21:50 AM US Mountain Standard Time, 
painter@magnet.fsu.edu writes:

<< I have a question that someone out there may be able to
 easily answer from their experience.  Is there a typical
 percent reduction in value of the V-I trace between exposure
 to full sun versus the "shaded" situation?  Any comments
 would be appreciated.
 
 Thanks,
 
 - Tom
 
 _____________________________________________
 Tom Painter                    
 Associate in Engineering
 National High Magnetic Field Laboratory
 Florida State University
 
 Phone: (850) 644-5752
 Fax: (850) 644-0867
 E-mail: painter@magnet.fsu.edu >>
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