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Wire sizing for hookup to controller? Controller has small area to connect wires....

desertratt

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Dec 14, 2021
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11
So i had old PVM system they had 1/0 for negative connected to lugs on the old controller and #8 for the positive.Well i plan on putting a switch before and after the controller question is what wire size can i get away with to connect to the controller? I have 10 coming into controller. also noticed the mt50 monitor i have ha a 6ft cord which is worthless can i use a standard computer cable?

thanks rick
 
You need to use a wire gauge calculator (example: https://baymarinesupply.com/calculator ...just one calculator of many I randomly pulled up), to figure out what your gauge should be based on voltages, amperages, conductor type, and distance. You will need to know the PV run voltage and amperage (by calculating series/parallel number of panels, panel specs, to get PV circuit volts and amps max on the run), for the PV input side.

For controller output side (to battery bank), need to know the same, max amps and volts the charger can provide to the battery bank, and length, etc..

In many cases, a 10 awg wire is max PV input wire size (hard to find MC4 connectors that support larger than 10 awg), although I am running 8 awg on mine for long distance part of the run (and 10 awg from panels to the DC combiner box). Again, I added up all my panels, 4s6p and calculated max volts (Voc), and amps (Vmp) on the circuits, and sized accordingly to provide minimal voltage drop. I actually have 3 home runs, two 4s paralleled on each PV circuit for mine, going to 3 PV inputs on the charge controller end.

Battery side can depend a lot on whether is 12v, 24v, or 48v (as 12v has much higher amperage, than 48v for example), so lower voltage needs larger wires for example. The charge controller manual should be able to provide specs on its battery charging capability on the different voltages (and if it can operate on different battery voltages even).

And then you need to size breakers or fuses on both circuits in accordance to protect the wires.
 
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Hard to say without knowing the amps/volts/watts coming from your panels or the length of wire run. Same thing with wires from the controller to the battery, what is the amp/volt/watt rating of your controller and length of wire run to your batteries.
 
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