[RE-wrenches] Two strings of Different Orientation

[Bill Brooks]

Peter,

Not to belabor the issue, but your understanding of the I-V curve and how it
responds to changes in irradiance and temperature are flawed. I'm sorry you
believe that I am misleading you, but the truth is that the I-V curve moves
up and down with changing irradiance (current changes with irradiance), and
the I-V curve moves left and right with temperature (voltage changes with
temperature). Without these fundamental understandings, we do not have an
understanding of the I-V characteristics of a PV device. 

At lower irradiances, some PV modules will slightly reduce in max power
voltage for a given temperature, but the temperature is not constant. As the
irradiance reduces, so does the temperature, causing a slight increase in
the max power voltage. These two counteracting aspects of the I-V curve make
the max power voltage of a PV array nearly identical throughout the
temperature and irradiance range for a given ambient temperature. Thus, the
ambient temperature is the ultimate deciding process on voltage in a round
about way. I hope we can come to a meeting of the minds on this some day.

Bill.


Peter,

The issue is the same as it was last year. 
[#] But it hasn't been resolved to my satisfaction, yet
The operating voltage of each
string will be nearly identical throughout the day if the strings are the
same length and not shaded. 
[#] This can't be the case. After all, the SE sub-array will have greater
irradiance than the SW sub-array in the AM and the converse will be true in
the PM 
Put them on a single inverter.
[#] I'd dearly like to.