# wire and controller size for solar panels



## budgetprepp-n (Apr 7, 2013)

Hi
I am getting ready to ad two solar panels to the 300 watt set up I have now. I'm going to set it up as a
totally separate system but feed the same battery bank I use now so I will have 1 battery bank with two
systems feeding it. I have put the spec of the panels below I thought they were 265 watt but they are a little 
smaller than that.

One of my questions is will a #12 solar wire be big enough to go from the panels to the controller? 
I will be wiring them in Parallel I know if I wire them in series that I could use a smaller wire but I 
did some experimenting with parallel and series and series don't do well here. Maybe in the desert
or something but not here.

Also what size controller do you guys think I will need? 20 amp 30 amp 40 amp? 
I will be using a MPPT controller

These are the panels I will be using


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## sparkyprep (Jul 5, 2013)

8.02 A x 2= 16.4 amps. #12 awg wire is good for 20 amps. Good to go.


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## budgetprepp-n (Apr 7, 2013)

sparkyprep said:


> 8.02 A x 2= 16.4 amps. #12 awg wire is good for 20 amps. Good to go.


How many amp controller do you think I will need?


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## sparkyprep (Jul 5, 2013)

I would go with the biggest controller that I could afford, simply for the reason of the potential for adding more panels in the future.


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## budgetprepp-n (Apr 7, 2013)

I'm going to set this up as two separate systems feeding into one battery pack.
So how big of a controller for just these panels?


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## LDSreliance (Sep 2, 2014)

budgetprepp-n said:


> I'm going to set this up as two separate systems feeding into one battery pack.
> So how big of a controller for just these panels?


You really don't want to have 2 charge controllers charging the same battery bank. It can work but it is a pain in the rear and really isn't necessary. If you want to have multiple arrays of panels or "strings" so be it but you only need to have one charge controller (and probably a MPPT controller if you anticipate having different types of panels). I would collect the power from the 2 systems into a combiner box (very easy DIY build) and then have one set of wires feed the one charge controller which charges one battery bank. You have a lot of really good ideas but the KISS method of keeping it simple really applies here.


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## pheniox17 (Dec 12, 2013)

Don't forget some diodes to prevent a feedback to the panels....


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