You can just use whichever bus is easier to get to in the main panel since they are wired together, either with a large wire, or they can be physically the same piece of metal. By my understanding, the power output of my SCC is 70A max, so a 6 AWG wire should be sufficient from the SCC to the Busbar (going off the Blueseas wire chart) I am planning on using 4 AWG just because I like to oversize a little. Victron recommends 1/0 wire from the Inverter (I assume that is. Cables and busbar systems are the most common and reliable ways to do so, at least until wireless energy transport is developed :) However, many potential issues need to be addressed. This article deals with four significant precautions you should take – grouping conductors in parallel, short. In order to avoid very thick cables, the first thing you should consider is to increase the system voltage. A system with a large inverter will cause large DC currents. Which means that both grounded (neutral), and equipment grounding conductors can be terminated on either bus bar. In the subpanel, the bus bars are kept separate. Also, I'm planning on trying to clean up the mess of wires in my panel.
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