DC Voltage Drop

[Andrew445]

I have a question that I am probably over-analyzing.

So I'm looking at voltage drop for the DC PV output conductors (from combiner to inverter), trying to limit to 2%. Now I can do this individually pretty easily. My question is what happens when the feeds meet in the inverter? They are essentially parallel voltage sources right? Is the resulting drop the average of the individual drops? Is it limited to the lowest voltage feed? Do they not affect each other at all? I think I am straining too hard here. Someone put me back on course!

Thanks!

 

[GoldDigger]

I have a question that I am probably over-analyzing.

So I'm looking at voltage drop for the DC PV output conductors (from combiner to inverter), trying to limit to 2%. Now I can do this individually pretty easily. My question is what happens when the feeds meet in the inverter? They are essentially parallel voltage sources right? Is the resulting drop the average of the individual drops? Is it limited to the lowest voltage feed? Do they not affect each other at all? I think I am straining too hard here. Someone put me back on course!

Thanks!

Yes, they are parallel sources. And the voltage drop in each wire will be proportional to the current through that wire. Since you are really concerned here about wasted power rather than under voltage, you can ignore the fact that they will all be forced to the same voltage at the combiner. The voltages at the panel end of the wire will change to keep the voltage drop equal to the current times the resistance. This is because the panels are primarily a current source rather than a voltage source.
Of course once you have combined them, the current through the downstream conductors will be the sum of the individual currents, and you start a new calculation from there. When you are through with that, you ADD the two calculated voltage drops and see whether it is still under 2% of the system voltage.
Do not try to manipulate the percentages. Just calculate the voltage drops until you are done and then look at the resulting percentages.