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Post by timsim00 on Dec 22, 2016 10:02:23 GMT -8
I have 4 100W 12V panels wired in parallel to my CC now and am adding 2 150W 12V panels in the next week, all will be in parallel.
My current panel cabling is 10 AWG. Can this handle the additional current, up to 40A? I have commonly the answer as NO, but want to make sure.
Thank you.
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Post by johann on Jan 29, 2017 15:58:55 GMT -8
A #10 wire can handle 30 amps as general means before the wire gets warm or hot. But there is a problem to generalize that.
The longer the wire, the more resistance you will have and the more the voltage will drop with the same load (in this case the charge controller and the battery at least I assume). Less voltage means that you send less wattage along the wire since the resistance will turn some of the power into heat and if the voltage is to low, then the batteries may end up to be undercharged. A bigger wire will decrease the resistance and the voltage drop will be lower and the voltage going to your charge controller and battery will be higher, because you have less losses.
If you parallel panels the voltage from old to new should be within 10 % of the panels.
If you series panels the amperage should be within 10 %.
In general, a voltage drop of 3% to no more than 5% is acceptable. Look up the internet for a voltage drop calculator, there are plenty out there. I do not know if I am allowed to post a ling to such an calculator.
Don't forget, every panel should have a fuse or breaker to prevent a possible fire if a panel malfunction and short out.
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Post by Tuscany on Feb 28, 2017 13:58:04 GMT -8
Rather than replacing all of your current 10AWG with heavier gauge you could consider adding parallel 10AWG to each existing line and using the heavier gauge only to the new panel (s).
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Post by johann on Feb 28, 2017 21:18:20 GMT -8
The proper way would be to fuse or use a breaker per panel so panels can not back-feed if something is going wrong and starting a fire, and then run each string/panel into a combiner. From the combiner to the charge controller use a big wire that can handle the combined current and use a fuse or a breaker again.
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