[RE-wrenches] Inverter with two strings of different orientation

[boB Gudgel]

Peter Parrish wrote:
> Bill,
>
> I looked into this several years ago, and I was able to get some digitized
> I-V data. I can't find that now (but I will). The data supports my claim. 
>   
Vmp does change with irradiance.  It just changes  very little. Depends 
on your definition of "change" I guess.
Negligible I would say... That is, assuming a higher irradiance than 
"dark" of course.

I can see where some confusion might come from from irradiance and PV 
parameter variation...  As the irradiance
changes, the ratio of Vmp to Voc changes.  Lower irradiance normally 
makes the Vmp/Voc rise somewhat but only
because the Voc is changing.

Now, put two or more modules in series, then shade one of them and 
that's something entirely different.


Here's a good paper with some good data on this subject.    I also see 
Bill Brooks contributed to this article,

http://photovoltaics.sandia.gov/docs/PDF/King%20SAND.pdf   (the %20  is 
a space)

And for temperatue relations, here's another good one:

http://photovoltaics.sandia.gov/docs/PDF/IEDFB5~1.pdf

boB