I shorted my Panels ... Are they Dead?

MrM1
MrM1 Registered Users Posts: 487 ✭✭✭✭
in PV Installers Forum - NEC, Wiring, Installation #1
OK so I know it was a dumb thing to do.  I was hot and had been on the roof most of the day and was not thinking clearly. 

I bought 9 285w REC TwinPeak 2 panels.  I also bought 3 30 foot cables with the idea of cutting each of  them in 2 to run 3 series strings of 3 panels  to  a combiner box.  Hear is where the "fun" starts.  I was not thinking ... or more specifically was thinking more about wire length as I knew it would be tight getting everything to the combiner,  so I never actually cut the cables (+ and -) in to 2 parts I connected everything to find out where the "center cut point" of each cable would be.  I plugged in the series strings,  and then plugged in the cables,  BEFORE cutting them in 2.   So the series strings were shorted.  Probably for about an hour in full mid day sun.

Are they now dead?  The VOC rating for the strings @ STC should be 115.8, and at NOTC should be 107.4.  I am getting between 95.6 and 100.7 VOC.  I cannot test the ISC because I cannot easily take the panels apart.    And I do not yet have the Charge controller,  so I cannot simple just "hook it up" and see.

But will shorting the panels in full sun for an hour or more definitely "kill" them ? 

How bad is it?
REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2017 / System, Pics and Discussion
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Comments

  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #2
    If you have continuity (which you do) you should be fine. Check them out tomorrow...

    You may have some contact burn but in general, my understanding is, you can short out panels without other damage

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • MrM1
    MrM1 Registered Users Posts: 487 ✭✭✭✭
    #3
    Well I just re-read the spec sheet.  And If I am seeing it correctly ... the Nominal Power Current @ STC is 8.95a and the Short Circuit Current @ STC is 9.49 ... a difference of .54 amps between the shorted current and the operating current.   So very very close.

    And interestingly, when I read the NOCT numbers for the same (which I assume the NOCT numbers are probably more real world day-to-day expectations for the panel) ,  The Nominal Power Current @ NOCT is 7.24a and the Short Circuit Current @ NOTC is 7.68a.

    So would I be correct in assuming that my shorted current would have been probably around 7.68a .... which is actually LESS than the Nominal Power Current of 8.95a in the "lab" at STC ?   So my Short Circuit  would be lower than what would be being produced in ideal conditions for normal use?  




    REC TwinPeak 2 285W 3S-3P 2.6kW-STC / 1.9kW-NMOT Array / MN Solar Classic 150 / 2017 Conext SW 4024 Inverter latest firmware / OB PSX-240 Autotransfomer for load balancing / Trojan L16H-AC 435Ah bank 4S connected to Inverter with 7' of 4/0 cable / 24 volt system / Grid-Assist or Backup Solar Generator System Powering 3200Whs Daily / System went Online Oct 2017 / System, Pics and Discussion
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #4
    Yes if the panels were hot, they will produce closer to the NOCT values.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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