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Seeking opinions: discolored cells in Sunpreme PV modules

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  • Seeking opinions: discolored cells in Sunpreme PV modules

    I have had a new tracker (from Solaflect) installed and it's working fine as a system, but I am puzzled by a discoloration of some cells in the Sunpreme GxB 320T (bifacial) modules that seems to be very apparent during overcast and/or wet conditions. I originally thought it might be moisture incursion in the modules, then I speculated it was evaporation of dew or condensation on the glass due to temperature variations in the cells, but I have since figured out that the discoloration is entirely within the glass sandwich. I've been googling around but I haven't run across anything else that looks quite like it.

    Does anyone have experience with this or ideas? Should I be worried?

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  • #2
    Has performance been affected in any way(s) you can quantify to the installer or manufacturer, and that they can verify ?

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    • #3
      1) I'm astounded that there are shadows from guy wires on the array, who thought that up ?
      2) the areas look like it's some sort of contamination slowly working through. Is the back sheet damaged in any way in those areas ?
      3) pic #3 sure looks like the frame clamps could have distorted the panel and caused contamination in.
      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 ||
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      • #4
        Originally posted by J.P.M. View Post
        Has performance been affected in any way(s) you can quantify to the installer or manufacturer, and that they can verify ?
        That's the thing: it's hard to get anyone really excited about it because the system is producing -- sometimes at more than 100% of rated output.

        1) I'm astounded that there are shadows from guy wires on the array, who thought that up ?
        The wires obviously decrease output, which is balanced by decreased manufacturing cost. There really is no structure to the array other than guy wires (and more on the dark side) and little + shaped brackets at the corners of the modules. These are built and installed by Solaflect in Norwich VT and are a pretty common sight in the NH and VT area.

        2) the areas look like it's some sort of contamination slowly working through. Is the back sheet damaged in any way in those areas ?
        The back sheet is clear glass, just like the front. I haven't been able to find any obvious damage, although ONE of the affected cells is operating at very high temperatures that reach as high as 220 deg F in full sun, which is about 100 degrees F higher than all the others. But if the array as a whole is still producing to spec and nothing is visibly wrong and the thing isn't on fire then nothing is really wrong, right?

        3) pic #3 sure looks like the frame clamps could have distorted the panel and caused contamination in.
        I don't think those bolts actually compress the frame at all. All of the frames are under compression but the direction of the forces is always parallel to the array surface, directed towards the center of the array. That compression force could be a problem as it should be highest near the center of the array. It also could be subject to excessive torsion forces under windy conditions as the array wiggles around a little bit.

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        • #5
          Originally posted by tiggie View Post

          That's the thing: it's hard to get anyone really excited about it because the system is producing -- sometimes at more than 100% of rated output.



          The wires obviously decrease output, which is balanced by decreased manufacturing cost. There really is no structure to the array other than guy wires (and more on the dark side) and little + shaped brackets at the corners of the modules. These are built and installed by Solaflect in Norwich VT and are a pretty common sight in the NH and VT area.


          The back sheet is clear glass, just like the front. I haven't been able to find any obvious damage, although ONE of the affected cells is operating at very high temperatures that reach as high as 220 deg F in full sun, which is about 100 degrees F higher than all the others. But if the array as a whole is still producing to spec and nothing is visibly wrong and the thing isn't on fire then nothing is really wrong, right?



          I don't think those bolts actually compress the frame at all. All of the frames are under compression but the direction of the forces is always parallel to the array surface, directed towards the center of the array. That compression force could be a problem as it should be highest near the center of the array. It also could be subject to excessive torsion forces under windy conditions as the array wiggles around a little bit.
          While the system is producing, I suppose it's easy to say no measurable harm, no foul, but that seems a bit shortsighted. I'd put the installer and mfg. on notice with a certified letter stating your findings and concerns. My guess, based in very incomplete information, is that this type of design may be headed for some long term problems.

          Thinking about it a bit more, I'm wondering if what's happening may be caused, at least in part by what looks like the inherent flexibility of the design, or maybe the greater flexibility of some parts of the array framing, such as it is, relative to the rest of the framing and the panels. That is, the panels are insufficiently supported by the frame, with the panels taking part of the loading that would normally be taken by the frame, with that panel loading then causing panel deflection. Panels/cells don't take kindly to flexing or repeated/cyclical deflection from things like wind, which may be more or less constant or at least frequent if the panel support design does not have enough rigidity to resist such deflections. More conventional systems tend to be more rigid.

          The component of any wind vector that's normal to the array will produce bending moments in the array that, because of the design will be local, variable and difficult to quantify, but may be significant, especially given the array's apparent flexibility, and will also cause changes in the force component parallel to the array and perhaps transferred to the panels with resultant forces exerted in directions not parallel to the major axes of the panels. Think of a panel "squeezed" at catty corners such as one upper left corner and the other lower right corner. Such loading will be variable most of the time with the wind.

          Any wind induced torsion on the array will be from wind shear over (parallel to) the array, and will probably be cancelled out by wind acting equally over the array. In all likelihood, array torsion will be small enough to be ignored.

          Questions: Is there a location pattern with respect to the discoloration ? How many such areas are there ? How big are those areas ? Do the areas tend to have the same appearance ?
          Last edited by J.P.M.; 08-12-2018, 12:17 PM.

          Comment


          • #6
            This solution may not be meeting the support requirements for this frameless module. The specification sheet shows there should be support running parallel to the short side and connecting at 375mm in from the short end of the module.

            It also seems the issue is close to the central point of the array with unique support connection.

            Has Sunpreme specifically endorsed use of the product in this way? If not I would say it is a misapplication of their product.

            Comment


            • #7
              Originally posted by adoublee View Post
              This solution may not be meeting the support requirements for this frameless module. The specification sheet shows there should be support running parallel to the short side and connecting at 375mm in from the short end of the module.

              ...

              Has Sunpreme specifically endorsed use of the product in this way? If not I would say it is a misapplication of their product.
              It took me a while to realize that Sunpreme actually sells the frameless module with a conventional frame (a "T" suffix on the part number), if you want it, which is the module that is used in this array. Their specs don't really lay out any limitations in lateral forces on the frames, no doubt because it's generally a non issue for 99% of installations. The Sunpreme warranty has me covered, as long as the panels are not incorrectly installed (whatever that means). I placed an inquiry about this from the Sunpreme web site, but got no response. I'm not sure where to go from here.

              Comment


              • #8
                Originally posted by tiggie View Post

                It took me a while to realize that Sunpreme actually sells the frameless module with a conventional frame (a "T" suffix on the part number), if you want it, which is the module that is used in this array. Their specs don't really lay out any limitations in lateral forces on the frames, no doubt because it's generally a non issue for 99% of installations. The Sunpreme warranty has me covered, as long as the panels are not incorrectly installed (whatever that means). I placed an inquiry about this from the Sunpreme web site, but got no response. I'm not sure where to go from here.
                Usually the installation manual is the official reference for if the module was installed properly (I don't see a manual posted online for this T variant on quick look).

                My recommendation would to be to start the process of a claim on the "product warranty" which is 15 years and not dependent on performance degradation. It should be based on whether there was a failure in the manufacturing of the product, which means they will be quick to have you document that you used their product properly. It might take a while but it will help you get "closure" if that is what you are hoping for.

                The only reason to wait a while longer would be to see if the condition spreads to other cells or modules.

                I hope it works out to your satisfaction - please keep us posted.

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