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Old 05-23-2016, 11:52 AM   #10
djmarchand's Avatar
City: Litchfield, Ct/Punta Gorda, Fl
Country: USA
Vessel Model: Atlas Pompano 23
Join Date: Aug 2012
Posts: 4,890

The voltage drop on each #10 from the panel to the "combiner" (I assume that is a junction box) is about a 1/4 volt. The voltage drop from the combiner to the solar controller (which I assume is about 15 feet) is about .45 volt.

So the net voltage to the MPPT controller will be approximately 18.5 -.25-.45 = 17.8 which is fine for the controller and represents a 4% loss to the controller.

The current from the controller to the batteries will be maybe 15% more than the input, because the voltage is lower, so the voltage drop will be about .55 volts. That is significant and I would consider increasing the wire gauge to the batteries. Or you can relocate the controller closer to the batteries.

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