Adding solar with existing inverter/charger
I have a factory installed Xantrex RV2012 2000w inverter/charging installed in my motorhome. I am looking to add solar panels to help reduce generator runtime when we are dry camping, which is most o...
Forum Discussion
If you want to use the pre-installed wire, I am assuming #12 or hopefully #10 you should series all the panels and use an MPPT controller, though my 420 watts of panels are paralleled with #10 on the input side of the controller.
You can afford some voltage drop on the input side but not on the output side. Controller must be very near the batteries and connected with as large a cable as feasible. If within a couple of feet you could get away with #10. I have about 25feet of mostly #6 which gives me an unacceptable loss of 1 volt drop @ 20 Amps.
The one drawback to series panels is the basic rule (from Ohm's Law) that in a series circuit the current remains the same throughout the circuit. This means that if one or more panels is shaded, the total current will be what that panel produces, even if it is only an amp or two.
If/when I redo mine I will use series/parallel with the rear two in series, the front two in series, and then both sets paralleled. Where we park in Mexico for three months the rear panels are shaded by a building a couple of hours before the front ones.
When connecting panels, panels in series should have equal current output. In parallel, both panels should have the voltages as near to equal as possible.
You can afford some voltage drop on the input side but not on the output side. Controller must be very near the batteries and connected with as large a cable as feasible. If within a couple of feet you could get away with #10. I have about 25feet of mostly #6 which gives me an unacceptable loss of 1 volt drop @ 20 Amps.
The one drawback to series panels is the basic rule (from Ohm's Law) that in a series circuit the current remains the same throughout the circuit. This means that if one or more panels is shaded, the total current will be what that panel produces, even if it is only an amp or two.
If/when I redo mine I will use series/parallel with the rear two in series, the front two in series, and then both sets paralleled. Where we park in Mexico for three months the rear panels are shaded by a building a couple of hours before the front ones.
When connecting panels, panels in series should have equal current output. In parallel, both panels should have the voltages as near to equal as possible.
