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  • #76
    I just pulled up a "typical" 310 watt 72 cell panel. Voc. 46.4 volts. That is pretty high at STC. 2 series wired 310 watt panels in a cold morning sunrise will exceed the 100 Voc. rating. There are 60 cell 300+ watt panels available now that would eliminate that problem if you want/need the extra wattage.
    2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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    • #77
      Originally posted by littleharbor View Post
      I just pulled up a "typical" 310 watt 72 cell panel. Voc. 46.4 volts. That is pretty high at STC. 2 series wired 310 watt panels in a cold morning sunrise will exceed the 100 Voc. rating. There are 60 cell 300+ watt panels available now that would eliminate that problem if you want/need the extra wattage.
      It depends on where that are used. Along the coast, where Wrybread hangs out, it probably is ok. In the desert, where Carv likes to go, not so much.
      CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

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      • #78
        I just pulled up a "typical" 310 watt 72 cell panel. Voc. 46.4 volts. That is pretty high at STC. 2 series wired 310 watt panels in a cold morning sunrise will exceed the 100 Voc. rating. There are 60 cell 300+ watt panels available now that would eliminate that problem if you want/need the extra wattage.
        Have you confirmed that? I've never seen the voltage get anywhere near that on my two 310 watts/72 cell panels. I'll have a look at the highest voltage recorded when I'm there next, since the Tracer logs all that stuff. The temps where I am don't really get below 35 degree F though.

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        • #79
          Originally posted by Carv View Post
          For those of you who can handle it, are there any issues with wiring the system this way?
          A downside to running the controller through the distribution block, and not attached directly to the battery, is that there is some opportunity for the voltage feedback used by the controller to overestimate the battery voltage (depending on the specific feedback technique used by that controller), due to the resistance of additional terminations and wire. With 10 ft 1/0 conductors, even at 40 A charge current that influence should only be about 0.1 V, so it shouldn't be a deal breaker in this case.
          CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

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          • #80
            That's for the open circuit voltage. Your controller will only see that for a fraction of a second when it first wakes up. If your controller does log that I would be curious what voltage it sees compared to the STC rating. It should be higher unless your early morning temps are quite warm.
            2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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            • #81
              Originally posted by sensij View Post

              A downside to running the controller through the distribution block, and not attached directly to the battery, is that there is some opportunity for the voltage feedback used by the controller to overestimate the battery voltage (depending on the specific feedback technique used by that controller), due to the resistance of additional terminations and wire. With 10 ft 1/0 conductors, even at 40 A charge current that influence should only be about 0.1 V, so it shouldn't be a deal breaker in this case.
              Quality battery chargers have solved this with remote sensing for eons. Has solar caught up? Bruce Roe

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              • #82
                Originally posted by Carv View Post
                You know Sk if I'm too dumb to help
                Problem is I am not to dumb to help. The problem is you are to slow to learn. It had to be explained to 6 times by three people why you cannot use the frame as a Circuit Conductor, fine for a Ground Conductor

                MSEE, PE

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                • #83
                  Originally posted by Carv View Post
                  For those of you who can handle it, are there any issues with wiring the system this way?
                  T

                  Try learning how to draw a circuit for which I did for you a long time ago. Where are your fuses and distribution. Again here are the two basic layouts. Ignore the battery isolator.




                  MSEE, PE

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                  • #84
                    Originally posted by littleharbor View Post
                    I just pulled up a "typical" 310 watt 72 cell panel. Voc. 46.4 volts. That is pretty high at STC. 2 series wired 310 watt panels in a cold morning sunrise will exceed the 100 Voc. rating.
                    Yeah I pounded that into wyebreads head a few months ago and he still does not get it.
                    Last edited by Sunking; 05-20-2017, 12:33 PM.
                    MSEE, PE

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                    • #85
                      Originally posted by littleharbor View Post
                      That's for the open circuit voltage. Your controller will only see that for a fraction of a second when it first wakes up. If your controller does log that I would be curious what voltage it sees compared to the STC rating. It should be higher unless your early morning temps are quite warm.
                      Wyebread does not know the difference between Voc and Vmp. Yet another reason to use 60-cell 200 to 250 watt panel building blocks.
                      MSEE, PE

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