oversized wiring to charge controller
I'm at that education stage to go solar.Reading every thing I can absorb. The controllers I have looked at all have a max. #6 ga. connectors. I want to run at least #4 ga. What is the best way to adap...
Forum Discussion
rjxj wrote:
While buying parts from the solar dealer in Yuma he asked if we wanted him to calculate it for minimum volt drop. I said absolutely, you are the solar man. He said 4 gauge. He said he always recommends shooting for the lowest v drop and best practices in connections.
Dealer is never a "solar man", he is a "seller man" :D
"shooting for the lowest V drop" - yeah, sure. The lowest drop would be 0.000000000...1%, doesn't mean that everybody has to install a cable as thick as his hand.
Example. 2*24V panels in series, 500W total, 30ft cable to controller. V drop in cable #12 = 1.5%, in cable #10 = 0.9%. This is at peak current 8.5A. As RoyB noted, you don't always get max current stated in the specs (if ever), so the daily difference in solar harvest btw #12 and #10 would be 0.3 AH or less. Conclusion: #12 is enough, #10 is plenty and leaves some margin to add one more panel in future. There is no reason to run #6 or #4, in this case. For future expansion - add another 24V panel in series, with close Vmp and Imp, and go 24V bank if the controller is maxed up. Things should be planned for.
The OP is at the planning stage. Panels will be purchased at the same time - at least, for initial setup. Panels number, wattage and voltage will determine the wiring and the controller model. Now, WHAT panels and HOW MUCH wattage - I asked this and got no answer. There isn't much to suggest at this point.
