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

[Peter Parrish]

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. 

Let's take the simplest case (constant cell temperature) and what was a
fairly popular PV module: Kyocera's KC200GT. Although it is a little tedious
to calculate the MPP, I found the following: 

200 W/m^2 Vmp=25 V, Imp=1.514 A (37.9 W), 

1,000 W/m^2, Vmp=27V, Imp=7.58A (205W) 

For more realistic conditions (i.e. operating temperatures) the result will
be different and you could be right, but as far as constant cell temperature
concerned, there is a shift with irradiance. 

By the way, the way you can see that there might be a real effect here is to
notice that Isc is almost perfectly linear from 200 W/cm^2 to 1000 W/cm^2,
whereas Voc is linear with irradiance only from 600 to 1000 W/cm^2.

- Peter 

Peter T. Parrish, Ph.D., President
California Solar Engineering, Inc.
820 Cynthia Ave., Los Angeles, CA 90065
Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885
CA Lic. 854779, NABCEP Cert. 031806-26
peter.parrish at calsolareng.com