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-   -   solar panel wire size (8 awg wont fit) and mounting question (http://www.sailnet.com/forums/electrical-systems/65300-solar-panel-wire-size-8-awg-wont-fit-mounting-question.html)

funjohnson 06-04-2010 08:37 PM

solar panel wire size (8 awg wont fit) and mounting question
 
I just bought two Kyocera 135sx-UPU with the junction box and a BlueSky 2512ix MPPT controller. With this set-up I should be making about 18 amps at most (perfect conditions not seen in Michigan), but the wire run will be about 30' round trip. Based on these number the Berkshire wire I ordered was 8 AWG.

Unfortunately, both the junction boxes on the panels and the screw terminals on the BlueSky controller call for 10 AWG max. Is there some way to step down the wire size to work with both items? Should I just get the 10 AWG wire and hook it up that way?

For people that installed panels like these, what size bar stock did you use to make the cross bars for the panels? I was trying to stick with aluminum because it's easily available locally and I wont have to worry about corrosion as much. The thickest I could find was 1/4" by 1" but it still seemed too flexible. Has anyone tried using angle stock and cutting back a small tab for the solar panel frame? By the way, these are getting mounted on the 1" SS davits via Emarine's 1" rail mounts.

Thank you,

Matt

Paul_L 06-04-2010 09:00 PM

Matt,
What I did was use 10awg from the panel through the deck to a distribution block. Then 8awg to close to the controller. Then a butt joint from 8 down to 10awg. The large wire size is used to reduce the voltage drop, not because it is required to handle the current level.

Paul L

btrayfors 06-04-2010 09:04 PM

Matt,

I'd use the AWG8 that you have. To connect it to the terminals, you can either:

(1) use a short length of AWG10 wire connected to the screw terminals and splice into the AWG8 close by; or

(2) trim a few strands from the AWG8 so it will fit nicely into the screw terminals.

Bill

scottyt 06-04-2010 09:37 PM

you do want to keep as large of a cable as you can, esp if you are using an mppt controller. losing the extra volt is not a big deal on a standard charge controller as they dump the extra anyway, but the mppt can use it. and running 10 gauge for 18 amps looks okay from the voltage drop end but dont do it.

as for the connections, you could use a butt connector to step down to 10 gauge, or a block as mentioned. i personally would very carefully trim a few conductors to make it fit as some one said

funjohnson 06-04-2010 10:45 PM

Thanks guys.

Should I put anything on the screw in terminals to help prevent corrosion?

lshick 06-05-2010 06:29 AM

You asked "For people that installed panels like these, what size bar stock did you use to make the cross bars for the panels?"

I used 1.5" x 1.5" x .25" aluminum angle for the framing, purchased (next day delivery) from McMaster-Carr, which is a great resource. The actual mount of the solar panel to the radar arch was 1.5" x 1.5" x .125" aluminum box channel. You can see the result at my projects page.


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