My Calcs for 24 x Canadian Solar CS6P-260M

Discussion about the Power System PV Combiner (PSPV)

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Lance
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Posts: 53
Joined: Thu Aug 21, 2014 4:36 am
My RE system: 30xCS6P-260M,2xFM80,Radian 8048,GSLC-175PV,FNDC,MATE3,24xL16RE-B

My Calcs for 24 x Canadian Solar CS6P-260M

Post by Lance » Fri Sep 05, 2014 8:56 am

Mostly trying to resolve the PV to the CC part.
I looked here for some good calc and think I have it, but want my work checked :wink:

I plan to run with 12 - Strings of two panels
Panel Voc = 37.8 Panel Isc = 8.99A
String Voc will be 75.6.
QUESTION#1 How will Voc be affected by a 0 degree F day? I get those! :)

12 Strings at 9A = 108Amps! QUESTION#2 How am I going to handle a shut-off for that?!

What gauge from the PVs to the Combiner? 9A x 1.54 = 13.86 QUESTION#3 Isn't this too much for AWG#12? How exactly do installers extend the provided leads to make it over to the combiner?

QUESTION#4 What AWG will I need from the Combiner to the CC? Assume a 50' run.

Wow, this is fun stuff! I can't seem to get enough of it.
L Michel
Rochester, NY
Lance
30xCS6P-260M,2xFM80,Radian 8048,GSLC-175PV,FNDC,MATE3,24xL16RE-B

gww
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My RE system: 1. installed
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Re: My Calcs for 24 x Canadian Solar CS6P-260M

Post by gww » Fri Sep 05, 2014 11:46 am

I won't tell you that the following is code correct, only how I answered these questions for myself.
QUESTION#1 How will Voc be affected by a 0 degree F day? I get those! :)
I just used a round about rule of thumb that I am sure is close. I took the VOC voltage and mutiplied it by 1.25.
12 Strings at 9A = 108Amps! QUESTION#2 How am I going to handle a shut-off for that?!
This sounds like a combiner box with 12 breakers/fuses rated 1.53% above the amps. I used breakers of 15 amps each and this is also how I shut off the panels, IE; I just flip the breakers to disconnect.
What gauge from the PVs to the Combiner? 9A x 1.54 = 13.86 QUESTION#3 Isn't this too much for AWG#12? How exactly do installers extend the provided leads to make it over to the combiner?
I went on line and found a line drop caculator. I had 24 panels and put the combiner in the center of the aray. Maby 25' longest distance to the combiner box. I found 12 awg to be fine and also used some 10 awg. I hear it might void panel warranty but I cut and spliced the panel leads. I was running 90 volts for 200 feet from the combiner to the charge controllers. I used 04 awg aluminum. Again this is where a voltage drop caculator will come in handy. You are lower voltage so getting this right will be more important.
QUESTION#4 What AWG will I need from the Combiner to the CC? Assume a 50' run.
Look in previous answer.
Hope this helps more then hurts.
gww

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