I have a Renogy solar suitcase 100 watt kit which consists of two 50w panels, which I bought to experiment with solar.
I recently bought another used Renogy 100 watt suitcase panel without a controller to daisy chain to my current one, and made sure they were both the same model number. I also bought a kit to crimp on some MC4 connectors, and an adaptor that takes two MC4 inputs into one MC4 output, and 30 feet of 10 gauge solar wire to make an extension cord.
In looking at the junction boxes for both of the panel kits, they appear to be different. In Panel A, the panels appear to be wired in series (negative wire on one of the 50w panels is wired to the positive of the second panel, and visa versa. There is a resistor across the positive and negative posts in the junction box. Here is a pic:
On the extension panel kit (Panel B), the two 50 watt panels appear to be wired in parallel: positive to positive, negative to negative. There is also a resistor across the positive and negative posts: Here is a pic:
Here is a closeup of the junction box:
So for a solar newbie, what's the best way to resolve this? Ultimately I want the positive leads from each of the kits to join at the MC4 2into1 adaptor to feed the solar controller. I don't mind monkeying with the extension panel since it is used and not under warranty.
Do I need to resolder the connections at the junction box of the extension panel to wire the two 50w panels in series? And what is the purpose of the resistor that is used on the main panel (A)?
Or, can I just combine the positive lead on Panel A with the Positive Lead on Panel B using the 2 into 1 MC4 adaptor (same with negative wires)?
Note, the Controller is a 20a PWM controller. I have handy a Victron 20a MPPT controller too, if that makes any difference.
Thanks in advance to the solar experts here.