discolored mono panels, should I worry?

I haven't done any testing yet, but I've noticed that while the cheap 0.50$ panels look fine under dim light, when I take them in the sun at the right angle whole collums of cells have a diffraction like discolorization. Kind of looks like oil on water color effect. Anyone know what this is?

Comments

  • solarvic
    solarvic Solar Expert Posts: 1,071 ✭✭✭✭
    Re: discolored mono panels, should I worry?

    Isn,t these the panels that had the junction boxs removed? There was a reason why. When you buy rejects you get what you pay for!!:Dsolarvic:D
  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    Re: discolored mono panels, should I worry?

    I'm with ;you vic,

    There must be A VERY GOOD REASON that the junction boxes were removed. Must have been a fatal flaw that some MFG did not want to put their names on, or even have someone TRY to use them. They must have been on the way to the DUMP, for someone to go to the trouble of removing the boxes. Tho, whatta I know ??

    Some of my MONO panels have a SLIGHT variation in the surface color twix cells in one panel, after exposure to the sun for six years. THis slight variation in color does not seem to corelated to any change in output.

    GOOD LUCK!! Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: discolored mono panels, should I worry?

    Most likely they were pulled because the assembled panels did not meet performance specs for any of the manufacturer's designations. The same panel might be labeled as a 225 Watt or a 235 Watt depending on what its test output is (yes, variations in cells cause the same configuration to produce different amounts of power). If the test showed "217 Watts" for example, they would be considered "out of spec" and unusable. Then sold off for experimenters (because there is no "217 Watt" panel in the product line).

    The discolouration is likely an indication of a few odd cells (crystal orientation perhaps). If output is suitable and the panel doesn't actually fail don't worry about it.
  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    Re: discolored mono panels, should I worry?

    Well, my opinion FWIW, is that there must have been every expectation that all of the cells were good enough to meet (at least) the midpoint of power output for that family of panels, BUT, in the assembly process something must hve gone WRONG. May have been a power output issue, a hermicity issue etc. BUT, since all of the cells were certainly tested, perhaps more than once for output, that there must have been a surprising flaw with those assembled panels. Even the Chinese MFGs use the standard Quality Motto, "Good parts make good assemblies".

    A few of these panels may fe fun to play around with, if one has the time.
    Just more guiessing. Back to "work". Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • meridiansolar
    meridiansolar Solar Expert Posts: 34
    Re: discolored mono panels, should I worry?

    solarmono.jpg

    this is what it looks like any idea of the cause?

    You can tell it is not simply random bad cells because the defect pattern would be more random if that was true.

    It's almost as if the defect "spread" around different cells as the pattern flows from one to the next.
  • Shane Jackson
    Shane Jackson Solar Expert Posts: 49
    Re: discolored mono panels, should I worry?

    Humm... that is odd. None of my laminates have that (at least that I have seen... Im half way thru putting on the j-boxes).

    Are you sure that is on the inside of the glass?

    What are you using for framing? Looks nice.
  • meridiansolar
    meridiansolar Solar Expert Posts: 34
    Re: discolored mono panels, should I worry?

    These are mono panels and you got poly panels. it is easier to detect defects on mono panels because the cells are supposed to be a black uniform color.

    yes it is on the inside and occurs on many different panels

    it is 8020.net aluminum extrusion.
  • The Original Ralph
    The Original Ralph Solar Expert Posts: 50 ✭✭✭✭
    Re: discolored mono panels, should I worry?

    not exactly an answer to the OP's post, but suspect it might help some at some point, plus not sure where else to put something i remembered the other day.

    back in the late 90's, we represented Raytheon Systems thermal imaging systems here in central VA, mainly to law enforcement.

    A solar panel mfgr in Williamsburg, Va had contacted Raytheon and wanted a demo of one of their camera systems (raytheon had a thermal imaging camera that looked like those early 90s VHS camcorders, with interchangeable lenses - LE could mount one on a chimney quite a distance from a suspect's house and maintain surveilance thru out the nite).

    Anyway, i was the one that went down to the mfgr's facility (for the life of me can't remember the name) - interesting operation, not terribly large but maybe 100,000 sq ft facility. They had about 20% of the building devoted to racks where they'd put the recently completed solar panels, flat to the floor (actually about 3' off the floor) and huge array of huge lamp housings hanging about 4-5' above them and they'd test the output from the panels and reject them based on output.

    One of the issues was cells that had poor connections - but they knew those connections would arc, ie on a microscopic level - they wanted the camera system to see if they could use it to detect those cell connections arcing before even being placed under the lights (i'd hate to have their power bill). The camera worked (keep in mind, a good thermal imaging sensor, back then, could detect 1/2 degree F differential at 1000 yards - at 100 yards, depending on conditions, you could read the name tag sewn onto military uniforms - with more reliabiity you could make out a pen in someone's shirt pocket, as the pen would cause the shirt to press against the wearer's body and acquire more heat than the area around that wasn't pressed hard against his body.

    They ended up building a large box area, over the assembly conveyor, that as the panel came down the line and went into the box (with lights), an operator would monitor the panel on his remote screen (kind of like the TSA scanner operator). They started on an automatic software program that would record each panel's image by S/N, and that system would detect any arcing between cells, for review later, in case there were issues.

    not too long after that I dropped Raytheon as a supplier - don't even know if the solar mfgr is still in business

    FWIW
  • Shane Jackson
    Shane Jackson Solar Expert Posts: 49
    Re: discolored mono panels, should I worry?
    These are mono panels and you got poly panels. it is easier to detect defects on mono panels because the cells are supposed to be a black uniform color.

    yes it is on the inside and occurs on many different panels

    it is 8020.net aluminum extrusion.

    No the panels I got were 245's (Mono's)... I''ll take a closer look at mine and let you know if I find any like that.

    Shane
  • RCinFLA
    RCinFLA Solar Expert Posts: 1,484 ✭✭✭✭
    Re: discolored mono panels, should I worry?

    The discoloration is likely due to junction doping baking temp variation. Sometimes cells at the end of oven rack get more temp variation with quicker cooling. It can also be caused by contaminated doping gas mix at ends of oven. It doesn't necessary ruin the wafer but it is one of the reasons by some cells produce more illumination current then others.

    As to thermal imagers, UL uses thermal imagers (IR camera) to detect hot spots caused by cell defects during qualification testing of panels. If manufacturer uses cells with severe shunt defects the cell can get very hot when shaded and other cells in series create high reverse voltage bias on the shaded cell. Bypass diodes every 12 to 24 cells keep the maximum reverse bias voltage down to less then 10 to 11 volts.
  • meridiansolar
    meridiansolar Solar Expert Posts: 34
    Re: discolored mono panels, should I worry?

    THE picture did have contrast increased the actual defect is much more subtle. I did not notice it till I took them out in the sun. sorry about my wrong assumption.
  • meridiansolar
    meridiansolar Solar Expert Posts: 34
    Re: discolored mono panels, should I worry?
    RCinFLA wrote: »
    The discoloration is likely due to junction doping baking temp variation. Sometimes cells at the end of oven rack get more temp variation with quicker cooling. It can also be caused by contaminated doping gas mix at ends of oven.

    it doesn't look like it is a cell manufacturing issue because the pattern occurs over several cells that are adjacent. radom bad cells wouldn't look like that.

    Almost as if the cells got overheated in some areas.
  • RCinFLA
    RCinFLA Solar Expert Posts: 1,484 ✭✭✭✭
    Re: discolored mono panels, should I worry?
    it doesn't look like it is a cell manufacturing issue because the pattern occurs over several cells that are adjacent. radom bad cells wouldn't look like that.

    Almost as if the cells got overheated in some areas.

    Yes, on second look I noticed that. Must be laminate outgassing or some other contaminate present at time of lamination to front glass (assuming it is not plastic).