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I wouldn't worry about dew. If there isn't enough sun to vaporize it, the panels wouldn't be producing much anyway.1
Without a voltage sense wire, the CC only sees the voltage on its end of the charging wire. With high current relative to wire size, the voltage on the battery side could be materially lower. If the controller holds an absorb voltage of (eg) 59v, but the actual voltage at the battery end is (eg) 57v because of the voltage drop, the battery could end up deficit charged. If there's only charging (no loads) going on, this would be mitigated somewhat, because as the current required to hold 57v battery side voltage drops off, the voltage drop from wire loss would decrease. With a long enough absorb, the voltage would eventually converge, but more likely the cycle times out or the sun goes down before then.
Some (most?) CCs have a setting to adjust for voltage drop which, absent a sense wire, can compensate for the drop. Of course, you need to measure the actual drop to set a reasonable value. I was going to suggest @Nila do this, but he plans to replace wire.
In my system, I have a shunt and WBjr measuring voltage and current to/from battery buss, and adjust the CCs for the small voltage drop from buss to batteries (0.1v IIRC, which is probably about as accurate as I can expect my cheap MM to be).1
As well as potentially being as waste of power, I would also be concerned about voltage drop between the batteries and charging source(s). I don't see voltage sense wire (or remote temp sensor). If the drop is large, it could lead to chronic undercharging.1
Hard to tell from the pic, but the cable for battery interconnects and to inverter look pretty light to me.1
It seems to me the basic tenet of a science is the ability to form falsifiable theories. This can be a problem even for hard sciences at times. For example, there were a ton of advances in physics early in the 20th century, but few practical experiments available to falsify theories. Without the tech needed to falsify, the incorrect theories live on.
Astronomy is accepted now as a science, but for centuries is was mostly bunkum mixed in with a little bit of reality. With the right tools, the bunkum got falsified, and the "predictive range and accuracy" started improving.1