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  • #16
    Originally posted by J.P.M. View Post
    The estimated year long summation of lost production over a 5,040 Watt output
    amounted to a grand total of 2.335 kWh/yr.
    Not to be concerned, about 2 KWH a year. This week I achieved an improvement
    of 2 KWH a day by changing connections to two inverters, to slightly reduce clipping.

    The PVwatts prog HOURLY OUTPUT is useful for you because of your ideal weather. It isn't useful here in cloudy
    NW IL, because the program arbitrarily inserts cloud losses on an hourly basis. Looking for the peak is moot when
    clouds are present. This was immediately evident when I did hourly graphs of some days.

    Number crunching programs are very useful, once their integrity and limitations are established. I do not care to
    simply accept any output without a sanity check; the slide rule guys (of which I once was one) did well because
    they had a pretty good idea of the answer before doing the calculations. My favorite check is the curves, and
    programs that produces them give me infinitely more confidence.

    The 5300 W DC unclipped limit was based on efficiency here: 1.2% DC losses
    and 3.8% inverter losses give about 5040 W AC. Bruce Roe

    Comment


    • #17
      Originally posted by bcroe View Post

      Not to be concerned, about 2 KWH a year. This week I achieved an improvement
      of 2 KWH a day by changing connections to two inverters, to slightly reduce clipping.

      The PVwatts prog HOURLY OUTPUT is useful for you because of your ideal weather. It isn't useful here in cloudy
      NW IL, because the program arbitrarily inserts cloud losses on an hourly basis. Looking for the peak is moot when
      clouds are present. This was immediately evident when I did hourly graphs of some days.

      Number crunching programs are very useful, once their integrity and limitations are established. I do not care to
      simply accept any output without a sanity check; the slide rule guys (of which I once was one) did well because
      they had a pretty good idea of the answer before doing the calculations. My favorite check is the curves, and
      programs that produces them give me infinitely more confidence.

      The 5300 W DC unclipped limit was based on efficiency here: 1.2% DC losses
      and 3.8% inverter losses give about 5040 W AC. Bruce Roe
      Bruce: The PVWatts hourly, or monthly output for that matter, is, within it's limitations, and in many ways because of its simplicity, designed to be useful in most climates without limitations with respect to atmospheric clearness indices.

      I, and I expect most folks more knowledgeable than I in such matters would take issue with your statement that PVWatts, or other such models have their validity and perhaps accuracy, whatever that may or may not mean, dependent on how cloudy a site's conditions might be. Within the stated limitations of the model, which are many, and within the dictates of common sense, using such models usually manages to produce estimates that probably have about the same confidence levels pretty much regardless of location.

      To whit: the PVWatts program does not, as you write, arbitrarily insert cloud losses (whatever that term may mean) on an hourly basis, as a cursory review of how irradiance values are determined and used will allow you to see.

      I, and others might well take issue with how the TMY irradiance models that PVWatts uses calculate/estimate irradiance. I've ranted about some aspects of what I see as shortcoming in that arena on this forum, but the means and methods, whether I, or others, agree with them or not are published and open for review, generally understood, and mostly accepted as fit for purpose. They are anything but arbitrary, within the context of judgment and common sense necessary when dealing with chaotic and mostly unpredictable events such as weather.

      I, like you do not like to blindly accept software output (or logic) out of hand without checking. That's why I make sure I can do the same things most any model can do by hand calculation and verify output before I use it. Been that way throughout my engineering career, and also made sure all those I supervised could do with a calculator whatever any software they were using could do. That also meant I gained better insight into what the software was doing and usually learn something in the process. With that said, I can do the same things PVWatts and other solar models can do, do them by hand calc., and understand why and how such models do what they do. I'd respectfully suggest you try the same before dismissing solar canned software out of hand to find out not only the limitations but also the capabilities of such software.

      Looks like we'll need to agree to disagree on the usefulness of solar modeling software.

      Respectfully,

      Comment


      • #18
        Originally posted by jpoet View Post

        I summed each hour between the two arrays, and then looked for any total over 5040. I wrote a python program to do it.
        Just for the sake of understanding, which specific weather file did you use? When I choose (TMY3) ALBUQUERQUE INTL ARPT [ISIS], NM, March 27th is a cloudy day. The 25th and 26th are clear in that file, though, and would run into a very small amount of clipping.
        CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

        Comment


        • #19
          Hey, not dismissing the software, just need to define any limitations. I ran some hourly curves for this area, and
          they didn't look anything like that nice bell curve. Sure weather is the reason, but unless I can turn that attenuation
          off, I can't try designs to sit on the edge of clipping. Bruce

          Comment


          • #20
            Originally posted by sensij View Post

            Just for the sake of understanding, which specific weather file did you use? When I choose (TMY3) ALBUQUERQUE INTL ARPT [ISIS], NM, March 27th is a cloudy day. The 25th and 26th are clear in that file, though, and would run into a very small amount of clipping.
            I used TMY2. The two stations are at the same lat/long, and TMY2 is the default. Just for the south array, I see:
            Station Month Day Hour Beam Irradiance (W/m^2) Diffuse Irradiance (W/m^2) Ambient Temperature (C) Wind Speed (m/s) Plane of Array Irradiance (W/m^2) Cell Temperature (C) DC Array Output (W) AC System Output (W)
            TMY2 3 27 12 937 201 3.9 10.8 1157.637 17.733 3603.774 3000
            TMY3 3 27 12 8 415 16.7 3.1 416.776 26.041 1260.72 1211.471
            Those are very different numbers! The total kWh/year difference between the two stations, is about 200.


            Comment


            • #21
              Originally posted by jpoet View Post
              Hi all.

              I am looking at:

              Qty 18 LG 330N1C-A5 (330W) solar panels with SolarEdge P400 Optimizers
              SolarEdge HD Wave SE5000H-US Inverter with 25 year warranty
              SolarEdge ModBus (consumption) meter
              Solar Edge WiFi Kit
              Main Electrical Panel Upgrade
              Unirac Solar Mount

              John
              The SE5000H is shipping now and the SE6000H will be shipping by the end of the month.

              but there is no WiFi kit for solaredge. There is a built in Ethernet, a zigbee gateway adapter and a GSM cellular adapter but no WiFi kit in the US
              OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

              Comment


              • #22
                Originally posted by jpoet View Post

                I used TMY2. The two stations are at the same lat/long, and TMY2 is the default. Just for the south array, I see:
                Station Month Day Hour Beam Irradiance (W/m^2) Diffuse Irradiance (W/m^2) Ambient Temperature (C) Wind Speed (m/s) Plane of Array Irradiance (W/m^2) Cell Temperature (C) DC Array Output (W) AC System Output (W)
                TMY2 3 27 12 937 201 3.9 10.8 1157.637 17.733 3603.774 3000
                TMY3 3 27 12 8 415 16.7 3.1 416.776 26.041 1260.72 1211.471
                Those are very different numbers! The total kWh/year difference between the two stations, is about 200.

                Yes, they are totally different. Read and understand why they are different in the TMY manual. The data for TMY2 and TMY3 for the same calendar date will be from a different year. Some extra care in interpretation is needed when using hourly data.
                Last edited by J.P.M.; 06-11-2017, 12:53 AM.

                Comment


                • #23
                  Originally posted by ButchDeal View Post

                  The SE5000H is shipping now and the SE6000H will be shipping by the end of the month.

                  but there is no WiFi kit for solaredge. There is a built in Ethernet, a zigbee gateway adapter and a GSM cellular adapter but no WiFi kit in the US
                  Do you know why the US model doesn't have the WiFi kit? Seems like most electronic equipment is getting away from any hardware Ethernet connections and going to wireless.

                  Comment


                  • #24
                    Originally posted by ButchDeal View Post

                    The SE5000H is shipping now and the SE6000H will be shipping by the end of the month.

                    but there is no WiFi kit for solaredge. There is a built in Ethernet, a zigbee gateway adapter and a GSM cellular adapter but no WiFi kit in the US
                    Right, it is the zigbee that is included. Zigbee seems an odd method to me, but I don't know that much about it.

                    Sorry for the confusion.

                    Comment


                    • #25
                      zigbee is a modern standard, but like bluetooth, low speed, low power, and needs matching zigbee hardware at the other end.
                      Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                      || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                      || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                      solar: http://tinyurl.com/LMR-Solar
                      gen: http://tinyurl.com/LMR-Lister

                      Comment


                      • #26
                        Originally posted by Mike90250 View Post
                        zigbee is a modern standard, but like bluetooth, low speed, low power, and needs matching zigbee hardware at the other end.
                        Some of the new POCO smart meters have the ability to communicate using zigbee but you usually need the password from the POCO to connect to it.

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