breaker tripping

I have two arrays wired into my flexmax 80. One is six 60W panels with a 20 amp breaker; the second is two 290W panels with a 30 amp breaker. After the two breakers they are combined with a big wire nut and a wire to the controller. The 30 amp breaker tripped three days in a row. Short circuit current on those two panels is 8.6 amps, so x 1.25 x 1.25 I get 27 amps as the max possible from that array. Should I buy a new 30 amp breaker to see if the breaker is bad, should I get a bigger breaker, or have I maybe wired something wrong?
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Comments

  • scrubjaysnestscrubjaysnest Solar Expert Posts: 175 ✭✭✭
    Isc of 8.6 amps sounds low for a 290 watt panel. I suspect it is closer to 10 amps if these are 24 volt panels. What is Voc and Vmp and Imp? Panel wattage = Vmp X Imp. What do they say to fuse the panel for?
  • AnitaAnita Registered Users Posts: 14
    290 Watts
    Watts (PTC): 261.1 Watts
    Max Power Voltage (Vmpp): 35.9 Volts
    Max Power Current (Impp): 8.08 Amps
    Open Circuit Voltage (Voc): 44.4 Volts
    Short Circuit Current (Isc): 8.64 Amps
    Max System Voltage: 600 Volts
    Series Fuse Rating: 15Amps
    Module Efficiency: 15.11%
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    2 @ 8.64 A panels in parallel = 17.28A plus the other 60W panel out oput... Was it cold and sunny?
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • AnitaAnita Registered Users Posts: 14
    The 60W panels are going through the other breaker. It was a little cold, in the 20s I think. Yesterday was sunnier and it did not trip.
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Keep a close eye on it, your suspicion of a bad CB may be right. What brand is it?
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • AnitaAnita Registered Users Posts: 14
    It is a Square D QO
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    The older QO breakers were only rated for 48Volts DC.... however the newest version of the QO's are, according to Schneider's site, are higher rated. 150V? but I don't know how to distinguish them from the old ones..
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • AnitaAnita Registered Users Posts: 14
    Should be under 48V, Voc is 44.4.
  • scrubjaysnestscrubjaysnest Solar Expert Posts: 175 ✭✭✭
    + 1 for the breaker, 44 volts is within 10% of 48 volts
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Did it trip at sunrise on a cold morning? That is exactly when you can expect an OVER VOLTAGE event, another is an edge of cloud event... most consistent times are on nice cold -40 days with clear skies...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • VicVic Solar Expert Posts: 2,970 ✭✭✭✭
    Hi Anita,

    What is the size of the cable that connects the 30 A QO Breaker to the FM-80?
    Have you checked the Torque on the breaker screw that connects the cable to the CC? It should be TIGHT. Are the QO breakers fully seated into the Load Center?
    What is the approximate temperature of the area where the breaker is located?
    Was the breaker previously used? )assume that this breaker is mounted in a Square D Load Center).

    Seems to me unlikely that this tripping is caused by the breaker being over-voltaed, but who knows at this point.

    As an aside, Schneider has a mention on their site that QO breakers "are available with DC ratings Up to 125 VDC "(or perhaps 150 VDC). This does NOT mean, IMO that ALL QO breakers are now rated to 125 - 150 VDC. Here is a recent Schneider (manufacturer of SQ D products):
    http://static.schneider-electric.us/docs/Circuit%20Protection/DC%20Rated%20Circuit%20Breakers/0601DB0401.pdf

    Here is the older spec for SQ D Breakers:
    http://ecatalog.squared.com/pubs/Circuit%20Protection/Miniature%20Circuit%20Breakers/QO-QOB%20Circuit%20Breakers/0730CT9801R108.pdf

    The only reason that am beating this drum AGAIN, is in an attempt to convey, that the DC Rating of some of the QO line of breakers is fairly narrow -- only 15 - 70 Amp ratings and for QO, QOB, and QOU models.

    Believe that Anita's application is within the limits of the standard QO specs.

    QO breakers appear to be rated for Continuous use at Handle rating up to 40 degrees C ambient temps.

    FWIW, Thanks for any added into. Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 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.
  • AnitaAnita Registered Users Posts: 14
    I have 6 ga wires going from each breaker to a wire nut and from the nut to the fm80. It's around 40 F down there. I purchased the breaker at Lowes in June, but I didn't install it until sometime in the fall. It is in a QO square D box.

    We did have clouds moving in and out the days it tripped, but it was definitely above zero F, maybe single digits on the day it did not trip.
  • VicVic Solar Expert Posts: 2,970 ✭✭✭✭
    Hi Anita,

    Thanks for the reply,

    Still seems unlikely, to me, that Cloud Edge Effects (just after the sun illuminates the PVs after being behind a fairly dense cloud) would cause the breaker trip, unless it is cold/windy out, or you are at a high elevation, or there is sun reflected from snow or perhaps water ...

    OK, so just the few remaining questions;

    1. Have you checked the Torque on the breaker screw that connects the cable to the CC? It should be TIGHT.

    2. Are the QO breakers fully seated into the Load Center?

    Either of the above could cause excess heating of the breaker, and a lower trip current, if not correct.

    3. What is your battery voltage,

    4. Are the two 290 W PVs in series or parallel?

    5. Are the six 60 W PVs wired in parallel, or three strings of two in series ... or??

    Thanks again, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 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.
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    It might help reduce line losses if you used lug type connections to a buss bar or even a SS bolt rather than wire nuts.
    If yo can find it on the makers web site there should be a couple of temp adjustment factor for your panel, you can use them to determine what the panel was putting out.something like this for a Mitsub 120W panel
    Coefficient of ISC = +.055% / *C, Coeff of Voc = -.346% / *C, and Coeff Pmax = -0487% / *C
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • VicVic Solar Expert Posts: 2,970 ✭✭✭✭
    To continue the aside regarding using QO breakers with system voltages exceeding 48 VDC ...
    Vic wrote: »
    ... As an aside, Schneider has a mention on their site that QO breakers "are available with DC ratings Up to 125 VDC "(or perhaps 150 VDC). This does NOT mean, IMO that ALL QO breakers are now rated to 125 - 150 VDC. Here is a recent Schneider (manufacturer of SQ D products):
    http://static.schneider-electric.us/docs/Circuit%20Protection/DC%20Rated%20Circuit%20Breakers/0601DB0401.pdf ...

    In looking at the above Data Bulletin from Schneider, several things become more clear regarding DC voltage ratings above 48 VDC. It appears that for a rating over 48 VDC, and up to 125 VDC, the QO and QOB SQ D breakers are used in series. Looking at Figure 2, it shows one breaker pole connected to the positive of the source, and the other breaker pole connected to the source negative. The load is connected between the output side of each of these breakers. So, at the very least this method requires a double pole breaker, or two single breakers to exceed 48 VDC, up to a maximum of 125 VDC. Seems to me that if single breakers are used, they should really be ganged.

    Also, it appears that when using the above approach, that there is no UL/CSA Recognition, rather, this approach to achieve voltage ratings above 48 VDC, it is noted that it is a "Square D Certified" application. This would probably not pass an inspection, although Inspections are not too common for the DC side of a PV power system.

    There may be other SQ D OQ breakers that are offered for system voltages above 48 V DC, but this is what have found to date ...


    FWIW, just to beat that old dead horse some more, Vic

    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 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.
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    The DC voltage rating of a breaker is almost entirely related to the breaker's ability to interrupt current at that voltage during a trip or a manual opening. It does not relate to the static breakdown of the insulation within the unit.
    And so exceeding the DC voltage rating while staying below the peak voltage of the AC rating is not going to cause a false trip.
    But if the breaker is opened manually under load a few times it could easily damage the contact surfaces of the breaker to the point where they would have a high resistance when closed and the resulting heat would lower the trip current.

    To allow the two breaker contact pairs in series to effectively split the job of stopping the DC arc they would have to open simultaneously both during manual operation and a trip. Handle ties might be enough to take care of the first situation, but not the second.
    For a fault current level to trip both contacts simultaneously would require a mechanical interlock called a common trip, not just a handle tie.
    It is possible to hold the handle of a breaker in the closed position and still allow the contacts to open. This is referred to a free tripping, and is required for UL listing. A consequence of this feature is that you cannot count on the tripping of one breaker putting enough force on the handle to open the breaker on the other end of the handle tie.
    SMA SB 3000, old BP panels.
  • VicVic Solar Expert Posts: 2,970 ✭✭✭✭
    Hi inetdog,

    Thanks for the detail. Am not a nitty-gritty code person. Had thought that the handle tie would have been enough, but this does not account for unmatched breakers with the same handle rating (believe that the single QO breakers still have a handle tie hole).

    And certainly, as you stated, the AC peak voltage of these breakers is over 350 volts, so this should not ever be the cause of a breaker trip in a 48 V (or lower) nominal system, under normal conditions.

    Have been trying to communicate that the SQ D QO line of breakers have a DC rating that has relatively narrow limits, that should be followed.

    The MidNite MNEPV (CBI) Breakers cost about $12 each (up to 63 A rating), and rated up to 125/150 VDC. They are just not available in the Big Box stores, and need an appropriate DIN Rail box for mounting. These are well suited to as PV and can also be used as battery breakers (10 kA rating).

    FWIW,. Thanks, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 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.
  • AnitaAnita Registered Users Posts: 14
    I was able to tighten the breaker screw significantly, thanks for that advice. I will let you know if it trips again. There was voltage on it even though all the breakers were off, it must have come from the PV input to the controller. Do they have a capacitor or something that holds on to voltage for a while? I left it for 24 hours and when I came back the voltage was gone (left all the breakers off since batteries were fully charged).

    I think it would cost $170 to get a midnite box and three breakers, plus my time to change it all out. Do you think my setup is a hazard or does it seem okay to keep an eye on it and if it doesn't trip again it's okay?
  • PhotowhitPhotowhit Solar Expert Posts: 4,996 ✭✭✭✭
    I think Robin(Midnite a major importer of breakers) once said he could count on 2 hands the number of breakers that had been bad, but there is that odd chance...

    From every think I've read I can't imaging a little extra extra voltage would cause the breaker to switch, particularly early in the morning with little amperage/current. even edge cloud events would be unlikely to sustain enough current long enough for the breaker to switch.

    You didn't happen to buy a 'house' labeled panel that might be a lower voltage panel with the wrong label... just thinking out loud...

    An interesting problem!
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • PhotowhitPhotowhit Solar Expert Posts: 4,996 ✭✭✭✭
    Anita wrote: »
    I think it would cost $170 to get a midnite box and three breakers, plus my time to change it all out. Do you think my setup is a hazard or does it seem okay to keep an eye on it and if it doesn't trip again it's okay?

    If you need an outside rated box for 3 breakers Midnite has some new ones on their garage sale section of their forum for $55 if it's in a weathered in area you could comfortably use a Baby box from NAWS for $30-35 so that and some breakers... bus bars for the baby box if you haven't combined the negative via 'Y's you should be out the door for $100 or less.

    Thought about these being true 24 volt panels, in the past some 24 volt panels could be wired for 12 volt, though by your specs I'd guess these are Canadian 290 CS6X panels?

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
  • VicVic Solar Expert Posts: 2,970 ✭✭✭✭
    Hi Anita,

    A breaker terminal screw that is not tight could cause excess heating inside the breaker. This extra heat, along with reasonable current, could cause the 30 A breaker to trip.

    Honestly, believe that we do not really know a lot about your system ...

    Is the battery voltage 12 or 24 V, or ??

    How are your two PV arrays configured? That is, are the two 290 W PVs in series or parallel ?

    How are the 60 W PV configured ... are they three strings of two PVs, or ... ??

    Really, there is nothing really wrong with the QO breakers and a QO Load Center (as long as it is NOT the Sq D Homeline series of breakers and panel), IMO, as long as the QO breakers are not exposed to voltages exceeding 48 V (at least not by very much above that).

    What is the breaker on the output of the FM-80 CC ??

    More later, Thanks for any added info, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 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.
  • AnitaAnita Registered Users Posts: 14
    Elevation 2800. There may have been snow one of the days.

    Batteries 12V.

    290Ws are in parallel.

    60Ws are two newer panels in series, two series sets of two older panels, the three strings in parallel.

    290s in parallel with 60s
  • AnitaAnita Registered Users Posts: 14
    Yes, Canadian 290 CS6X

    Pmax -.43%/*C
    Voc -.34%/*C
    Isc .065%/*C
    Normal temp 45C

    Does this mean that at -20F the Voc could be 11V higher, or 55V, putting me over the spec of 48V for the breaker?
  • AnitaAnita Registered Users Posts: 14
    70 amp breaker on the fm output. So far it says it has put out 63 amps max.
  • VicVic Solar Expert Posts: 2,970 ✭✭✭✭
    Hi Anita,

    Thanks for the added info.

    For now, would not worry too much about the potential over-voltage when the PVs are cold -- just my opinion and you should make that decision for yourself.

    The PVs cannot produce very much current, even into a direct short, so the breaker would not need to break a large current. AND, Voc is just that, voltage when there is NO current flowing, so that condition should not be a problem.

    If you do not have a Combiner with circuit breakers (of fuses) for the individual strings of PVs, you should probably consider adding one. It is very convenient to use circuit breakers, as they would allow individual strings to be switched on/off, for troubleshooting, etc.

    Here are some Combiners:
    http://www.solar-electric.com/installation-parts-and-equipment/midnite/pvarco.html

    Breakers for Combiners:
    http://www.solar-electric.com/installation-parts-and-equipment/midnite/cipr1/stfubr1.html

    You probably have seen the above items, before.

    The battery side of the FM-80, is where large fault currents can flow in the case of a failure of the FM CC. This is a breaker that must be able to handle large currents. The QO breakers should be able to do this job, as well. Although, have not seen any 70 A QO breakers at the Box stores. Is the breaker on the output of the CC also a QO? It is very important that whatever this breaker is, that it is DC rated. Arcs at 12-ish VDC are not as severe as those created during a fault, with higher battery voltages. What is the brand/model of this breaker?

    Thanks for checking and tightening that terminal screw on the PV breaker -- poor connections at breakers can create a lot of heat, and are dangerous, as the end of the wire at this connection could arc, if very loose, and that could possibly burn off the wire end, etc.

    FWIW, thanks for all the replies. More later, Vic

    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 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.
  • AnitaAnita Registered Users Posts: 14
    The 70 amp breaker is also a QO, I think I got it on amazon. I think it may be the largest QO there is, I am wondering if it will trip in the summer and I might need an 80 amp breaker.

    I have the 30 amp breaker on the new panels and the 20 amp breaker on the 60Ws, since they run in separate cables to the house. I don't think it would be that useful to have breakers out at the panels. I think I would only buy a new box if the QOs were not rated for my application, or if the positive bus bar would be better than the wire nut I currently have to combine them. But maybe I could get an isolated bus bar for the QO box. It's actually two separate boxes, the 20 amp breaker is in its own box and the 30 and 70 are in the other. If I need an 80 amp breaker I may need a new box if QO doesn't make one.
  • VicVic Solar Expert Posts: 2,970 ✭✭✭✭
    Anita,

    Thanks for added info.

    The Combiner with circuit protection for every string is for safety. If one cable to a PV, or one PV itself shorted, all of the other PVs would provide a lot of current into the short, when the sun is shining. This could easily cause a FIRE. Of all of the concerns that one might have, this is easily the most important.

    You really should have a Combiner, with Fuses or Circuit breakers for EACH STRING. You might check the Maximum Fuse Rating for the 60 W PVs. But, still the two 290s could dump over 20 Amps into all of the 60 watters, without tripping the 20 A breaker, and quite a few hours of a typical sunny day could pass before there was enough sun to trip that breaker.

    Just something to think about.
    The largest QO breaker that is rated for DC operation is 70 A, so you should not consider finding a larger OQ for the output of the FM CC.

    More later, Thanks. Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 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.
  • BB.BB. Super Moderators, Administrators Posts: 29,511 admin
    You could also program the maximum output current to (70 amp breaker * 0.80 NEC deraring=) ~56 amps for the FM 80 (I think you can program the maximum output current.

    Won't hurt anything and will keep the breaker from tripping during the middle of cool/clear/bright sun days (and reduce the output a little bit).

    Otherwise, up-sizing your circuit breaker (and your copper wiring AWG--American Wire Gauge--If needed) is the a better option (more energy harvested).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • VicVic Solar Expert Posts: 2,970 ✭✭✭✭
    Anita,
    Anita wrote: »
    ... I don't think it would be that useful to have breakers out at the panels ...
    I think I would only buy a new box if the QOs were not rated for my application, or if the positive bus bar would be better than the wire nut I currently have to combine them ... .

    Yea the breakers are convenient circuit protection, that can also act as a switch. There are PV Fuses that can be installed in Combiner boxes, and now are less expensive than are breakers. But if a fuse blows, it can be a bit of a pain to replace it, and then it approaches the cost of the MNEPV breaker, IIRC.

    There is nothing at all wrong with using Wire Nuts, they are accepted in the NEC (the Code). But would still suggest that you install a Combiner, with one breaker or suitable fuse for every PV string.

    Just my opinion. FWIW, Good Luck. Vic

    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 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.
  • AnitaAnita Registered Users Posts: 14
    So what I need is three new breakers out at the panels for the three 60W strings before they are combined, in an outdoor box.
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