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  • Newbie question - cracks in solar panel glass

    Hi everyone, new to the forum hoping to get an answer. I washed my solar panels this year as always once or twice a year and for the first time ever I see lots of small cracks in the glass of the panels. There wasn't any hail that I know of, nor any other stresses I can think of. Is this a big problem? Any ideas on cause and what it could lead to? Panels are about 13 years old and system is working fine. Thanks for any advice

  • #2
    By any chance did you wash them with cold water when they were warm from the sun? We've speculated that it might cause the glass to crack, but I don't know of anyone that has actually seen it happen.

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    • #3
      no i always wash them early in the morning, and would be aware of that possibility.

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      • #4
        is this all the panels, or just 1 or 2 ?

        Generally panels are tempered glass, and a crack anywhere propagates instantly over the whole panel, so if a baseball hit a corner, the whole panel will shatter into pea sized pieces. The laminate layer under the glass holds all the pieces together, but the damage is done and moisture will eventually destroy the panel
        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 ||
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        • #5
          It's not all of them, but it is hairline cracks in random places generally about 3-4"' long. Sometimes several in same area. I didn't count but on the 27 panels maybe there are 15-20 cracks.

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          • #6
            Photos? Brand of panels? This doesn't sound right unless these are some low quality thin film type panels that have non tempered glass.
            2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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            • #7
              They are "Andalay" panels that were sold by now bankrupt Akeena Solar. They are definitely tempered glass and look like good quality. Will try to climb up there to take pix later today.

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              • #8
                Also, they do not look like they have any "point of impact" wherever they cracked, as you might expect with hail. The really odd thing is the sudden formation of so many - I might have missed washing them last year, so it all happened in a year and a half, no sign of anything prior to that.

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                • #9
                  Tempered glass doesn't act like you describe. Could you possibly be referring to micro cracks in the individual cells?
                  2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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                  • #10
                    OP:

                    Please excuse my ignorance and help my confusion, 15-20 cracks total on 27 panels Or cracks on 15-20 panels ?

                    Is there a trend to the crack location on the panels, or are the cracks randomly distributed over the faces of the panels that are cracked ?
                    Is there a trend to the location of the panels that have glazing cracks on the array, such as at the array edges or over an area of the array that may now be (partially) shaded that was not previously shaded ? (by a growing tree for example).
                    Any change in shading since installation ?
                    A long shot : Any overspray from irrigation ? You'd probably notice (differential) hard water scale on some panels if that were the case. I've seen such patterns once/twice.

                    How are the panels supported ? Sometimes if a frame is less rigid in one or more planes than the lite of glazing it supports) moves, or if what the supports are anchored to moves, that can put stress on the glazing. Then, that added induced stress in the lite gets added to (diurnal cyclic) thermal movement and the additive effect can then induce a greater cumulative stress in the lite.

                    First time noticed, OK. I appreciate this may then be a dumb question: Have you noticed any crack growth since first noticed ?
                    Also, any directionality to the cracks or do they tend toward isotropy ?

                    Can you "feel" the cracks on the surface, or just see them ?
                    If you can't feel the cracks, could you perhaps be seeing some changes/degradation in the encapsulant ?
                    Any idea of glazing thickness ?

                    Any recent seismic activity ?

                    I'm also wondering if some cells are beginning to fail or their connections to adjacent cells on their panel are failing, with perhaps the result that the irradiance not converted to electricity and/or a short in the connectivity between cells is causing local heating of the glazing that is inducing the cracking. But - and a big but - depending on how the panels are wired internally, I'd expect you might see a decrease in performance if that were to be the cause of the cracking.

                    Just some random thoughts.

                    Welcome to the neighborhood.

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                    • #11
                      Ojk, I had another look and littleharbor is correct. It is not the glass, it is underneath, so I guess these are the microcracks? Until you get down real close it looks like in the glass, sorry about misleading. What is the prognosis if I have these? Pics attached. Looks like I didn't do a good job washing either, I'll have another pass at it now.
                      Attached Files

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                      • #12
                        I guess these are snail trails from what I can find online?

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                        • #13
                          Originally posted by scrptdr View Post
                          Ojk, I had another look and littleharbor is correct. It is not the glass, it is underneath, so I guess these are the microcracks? Until you get down real close it looks like in the glass, sorry about misleading. What is the prognosis if I have these? Pics attached. Looks like I didn't do a good job washing either, I'll have another pass at it now.
                          Well, the cracks appear to have the not quite smoking gun but quite likely indicator of failure due to a shear stress. That type of failure occurs at 45 deg., the point of max. shear stress. The question becomes the source of the stress, frame movement or thermally induced, or both, or other things, all perhaps in combination.

                          To me it looks like the glazing cracks may have initiated on the underside of the glazing and the encapsulant is following the same line. I'd think that the glazing is more brittle than the encapsulant and when the glazing gets a micro crack that would perhaps not otherwise be noticeable, the encapsulant accentuates the visibility. I kind of don't think the encapsulant would do what's being observed on its own without some local instigating condition such as a glazing microcrack.

                          Perhaps the cracks are not "feelable" on the surface in the same fashion a windshield crack may not be detectable from the vehicle interior side. If so, my guess is the panels will continue to function, but once a glazing crack allows moisture of other stuff in/behind the glazing, that panel will begin to fail and cause the string it's on to lose most or eventually all production capability.

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                          • #14
                            Looks like an issue with the encapsulant delaminating from the cell, especially due to the skipped nature of the flaw. There might have been some contaminant on the cell surface which is causing the release. I doubt this is going to cause any production issues if it doesn't spread in any substantial way. In my opinion there are no cracks in the glass.
                            2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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                            • #15
                              Originally posted by scrptdr View Post
                              I guess these are snail trails from what I can find online?
                              I thought that might be a possibility as well, but after your flicks and seeing the telltale 45 deg. shear stress pattern to what look like but may not be cracks, I moved that down my list of possibilities.

                              Still, and after thinking about it more overnight, I suppose it's possible - maybe even likely - that the first and most common location of delamination(s) may occur along lines of max. shear stress caused by slight and/or occasional panel/array movement or settling over time.

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