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  • Hiding stuff under the panel.

    The more I read about optimizers and micro-inverters the more I would run away so fast I might just leave my shadow standing there. I get that it may be the only way to make a marginal (shade, roof surface, etc.) solar installation palatable but so far I can't see any of these products in the 'glad you were here' category, regardless of technology and manufacturer. What am I missing? Let's not break out the automatic rapid shutdown thing, as far as I know nobody is on NEC 2017 yet.

  • #2
    Originally posted by AzRoute66 View Post
    so far I can't see any of these products in the 'glad you were here' category, regardless of technology and manufacturer. What am I missing?
    I have panels facing East, West, and South.
    I have multiple panels that have shade at different times of the day.
    I enjoy seeing per-panel data.

    If my panels were all facing south and shade-free, I'd probably go with a string inverter for the cost-savings.
    But they aren't. And the extra cost that I paid for the solaredge system I project will be paid for by the higher production. (My projections are based on my best guesses about what the benefits will be)


    I am also the primary contact with the contractor for a large-ish (196 module; 100 optimizers) shade-free installation.
    And the contractor specified and used Solaredge.
    That has allowed me to determine that one of the modules isn't yet producing. If they had done a set of string inverters I wouldn't have been able to easily tell that the module wasn't producing.

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    • #3
      Originally posted by AzRoute66 View Post
      as far as I know nobody is on NEC 2017 yet.
      Going to just leave this here for those making similar assumptions : http://www.nfpa.org/nec/nec-adoption...-adoption-maps

      And of course there is the rule 21 as well.
      We we have had many pv modules replaced based on the output of the solaredge modules.
      OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

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      • #4
        Thanks Bruce, didn't think the process went that quickly.

        foo1bar - Point taken about having individual panel monitoring, I am a data geek.
        Last edited by AzRoute66; 10-05-2017, 09:52 PM.

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        • #5
          Originally posted by AzRoute66 View Post
          Thanks Bruce,.
          Uh no problem. NMRoute99
          OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

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          • #6
            Originally posted by foo1bar View Post

            I am also the primary contact with the contractor for a large-ish (196 module; 100 optimizers) shade-free installation.
            And the contractor specified and used Solaredge.
            That has allowed me to determine that one of the modules isn't yet producing. If they had done a set of string inverters I wouldn't have been able to easily tell that the module wasn't producing.
            I'd divide not producing string in half, measure voltage, divide the half with lower voltage in half, measure again - takes 4 voltage readings max for 12 panel string to find single failed module. Multiple simultaneous failures hardly possible as they have to happen at exactly same time. Not as convenient as doing it from the computer but then again there's no extra electronics involved which can fail and misreport.

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            • #7
              I like the data. An optimizer failure will cost about $50 and 30 min of time to replace... I am happy to make that trade for all that I learn about my system.

              On my old house, the panel level data let them know that the vines on the side of the house had crawled onto the roof and were starting to affect the array. Catching that with string inverter data would be darn near impossible (of course there are lower tech ways to monitor vegetation, like flying a drone over the house).
              CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

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              • #8
                [QUOTE=sensij;n363507(of course there are lower tech ways to monitor vegetation, like flying a drone over the house).[/QUOTE]

                Yea, or like a low tech solution of walking around the house with a good eyeball when you're cuttin' the grass.

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                • #9
                  Originally posted by max2k View Post
                  I'd divide not producing string in half
                  Would you even notice that you have 0.5% less production than you should? or that one of the 4 inverters was producing 2% less than it should?
                  When you lose half (or 1/3) of the production on an inverter you certainly notice - but I'm missing 0.5% of the whole system and I'm able to tell that it is missing (probably never connected)

                  And I know that it's missing before the contractor gets their final payment.
                  So it's THEIR problem to try and figure out just which panel.

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                  • #10
                    [QUOTE=ButchDeal;n363494]http://www.nfpa.org/nec/nec-adoption...-adoption-maps

                    That link isn't working for me.

                    But this one via google
                    http://www.nfpa.org/~/media/images/nec/adoption-maps/nec-in-effect-0917.jpg?as=1&iar=1&&h=619&w=800&la=en
                    seems to.

                    shows MN, TX, WA, ND, SD, NE, WY, ID, CO, MA are using NEC 2017 as of 9/11/2017.

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                    • #11
                      Originally posted by foo1bar View Post
                      Would you even notice that you have 0.5% less production than you should? or that one of the 4 inverters was producing 2% less than it should?
                      When you lose half (or 1/3) of the production on an inverter you certainly notice - but I'm missing 0.5% of the whole system and I'm able to tell that it is missing (probably never connected)

                      And I know that it's missing before the contractor gets their final payment.
                      So it's THEIR problem to try and figure out just which panel.
                      I wouldn't and I don't care- in just 1 year the whole thing would lose about that much anyway. In my very limited experience my 2 identical strings feeding 2 identical inverters match to each other very well (<2% difference) making their total power curves indistinguishable on the graph which is probably 100 pixels high and doesn't even have resolution to show 0.5% difference. I think your expectations are a little unrealistic and I wouldn't worry about a thing within 10% variation. Digital output has this effect on users- they see all those numbers, make subtraction and start asking why the mismatch without realizing they're talking about mismatch in the second significant digit.

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                      • #12
                        Originally posted by max2k View Post

                        I wouldn't and I don't care- in just 1 year the whole thing would lose about that much anyway. In my very limited experience my 2 identical strings feeding 2 identical inverters match to each other very well (<2% difference) making their total power curves indistinguishable on the graph which is probably 100 pixels high and doesn't even have resolution to show 0.5% difference. I think your expectations are a little unrealistic and I wouldn't worry about a thing within 10% variation. Digital output has this effect on users- they see all those numbers, make subtraction and start asking why the mismatch without realizing they're talking about mismatch in the second significant digit.
                        Way to completely miss the point of what foo1bar wrote. It is very obvious in a Solaredge system when 1 out of 196 modules is not producing. That is where his 0.5% number came from, not mismatch.

                        How many panels would have to fail before you would notice on a string inverter... 20? Are you saying that less than that, and you would be fine with those modules not producing?
                        Last edited by sensij; 10-06-2017, 11:51 AM.
                        CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

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                        • #13
                          Originally posted by max2k View Post

                          I'd divide not producing string in half, measure voltage, divide the half with lower voltage in half, measure again - takes 4 voltage readings max for 12 panel string to find single failed module. Multiple simultaneous failures hardly possible as they have to happen at exactly same time. Not as convenient as doing it from the computer but then again there's no extra electronics involved which can fail and misreport.
                          Thats how its done here, after a DC clamp on says a string is weak. I insert 3 way MC4 adapters
                          at night, plug the extra port with one of my dummies. Then use a voltmeter with one very long lead
                          and MC4s (latch ground off) to make measurements in strong sun (time failures are most likely).
                          Bruce Roe

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                          • #14
                            Originally posted by sensij View Post

                            Way to completely miss the point of what foo1bar wrote. It is very obvious in a Solaredge system when 1 out of 196 modules is not producing. That is where his 0.5% number came from, not mismatch.
                            I thought he was talking about inter- module mismatch in that range.

                            Originally posted by sensij View Post
                            How many panels would have to fail before you would notice on a string inverter... 20? Are you saying that less than that, and you would be fine with those modules not producing?
                            exactly one- non producing module would degrade entire string. Besides strings can't be made longer that 14 panels in series due to 600V input voltage limit.

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                            • #15
                              Originally posted by max2k View Post


                              exactly one- non producing module would degrade entire string. Besides strings can't be made longer that 14 panels in series due to 600V input voltage limit.
                              right, so you have strings in parallel in a big system like that. Now, bypass one panel out of one of those strings. By itself, that string's voltage would fall by an easily detectable amount. In parallel with other strings, the voltage drop will be harder to see, since the mppt still wants to maximize power output, and those parallel strings aren't going to like having their voltage pulled down much.

                              of course, this only works in the case of exactly one failure. If you have a second failure before the first one was detected, and it happens to be in the other mppt that you are using for your reference voltage, now you've lost the ability to easily detect either failure.
                              ​​​
                              CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

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