Different Panel Wire Lengths Okay?

[guidecca]

In my case the three panels will be connected in parallel. The panel wires will all go to one homemade combiner box on the roof with all negative on one grounding bar and all positive on another grounding bar. All three positive panel wires will be fused with 20A inline fuses. A 6 AWG wire from the positive grounding bar and a 6 AWG wire from negative grounding bar will run from the combiner box to the inside of the van to a 63A breaker. Does it matter if the panel wires of one panel are longer or shorter than the panel wires of the other panels? Can I cut off the MC4 connectors on the panel wires to connect to the grounding bars? Can I add extension wires to some panel wires and skip others? Any help is appreciated. I'm trying to neaten up the top of the van and get the combiner box finished.

 

[guidecca]

So, if you add an extension wire to one of two solar panel wires do you get a significant change in voltage from no extension?
I don't think so.

 

[Hedges]

Large slope in I/V curve of PV panel, no reasonable length of wire will make any difference. Parallel PV panels may operate at slightly different voltage due to IR drop, but negligible; their power/voltage curve is pretty flat.

You can cut off MC connectors, but I find them convenient. I would get pigtails (or cables to cut in half) and used those to make the connection.
Unfortunately, not all "MC4" connectors are interchangeable, in fact are a fire hazard. Especially those fuse holders (ironic, meant as fire protection.) Only same brand & model should be mated, or mixed brands that are UL listed for use with each other. Probably difficult to find cables with same connector as panel, you may be able to buy connectors to install.

Are you limited to parallel, not series, by your charge controller's max voltage? (3s = 150V at 25C; probably.) I like connecting in series, but if tilted to different orientations they should be in parallel.