Does Outback CC shut off at 145v to protect itself?

Dan_
Dan_ Solar Expert Posts: 61 ✭✭✭✭
Manual seems to say it does but folks online have sometimes said otherwise. Manual excerpt attached. Particularly cold sunny day today and I'm worried.

Comments

  • Mountain Don
    Mountain Don Solar Expert Posts: 494 ✭✭✭
    Re: Does Outback CC shut off at 145v to protect itself?

    I can't say what it does with certainty as the highest voltage recorded here has been 141.
    Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Does Outback CC shut off at 145v to protect itself?
    I can't say what it does with certainty as the highest voltage recorded here has been 141.

    That's because depending on what software revision is installed they shut down at 141 Volts.

    You should never have an array that runs so close to the maximum V in. There is the possibility of damaging the controller even if it does cease operation first.

    If you need to run array Voltages in that neighbourhood you should use a MidNite Classic 150 or 200; their HyperVoc function helps protect the controller against unexpected cold Voltage spikes.

    Normally the Vmp for even a 48 Volt system would be no higher than 90, which leaves plenty of room to handle Voc on cold days.
  • Mountain Don
    Mountain Don Solar Expert Posts: 494 ✭✭✭
    Re: Does Outback CC shut off at 145v to protect itself?

    That voltage was recorded on the coldest day I've seen up here in the mtns. An unusually low of -21F combined with our gloriously clear bright skies. Other than that 141 the highest voltages usually are 110 to 120
    Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M
  • Dan_
    Dan_ Solar Expert Posts: 61 ✭✭✭✭
    Re: Does Outback CC shut off at 145v to protect itself?

    Thanks for the replies. I overreacted a bit, voltage only went up to 105. By the time sun gets high enough temps have already risen. I have a test setup of 6 panels with 21v voc at 25C. It is pushing it which I shouldn't do but I'm hoping to get by for now before the permenant setup is put in place.

    Separate question: is it normal for winter power output to be low? Have had 3 clear sunny days and the peak output from 720W of panels was 420W. I tested voltage on each panel and they all were good, approx 18v. Angle seems to have little effect.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Does Outback CC shut off at 145v to protect itself?

    Sounds a bit on the low side... If the panels (or several panels) are in parallel--use a DC Current Clamp meter or, disconnect one string at a time and make sure that all are producing near similar amounts of current per string. (note: If you are disconnecting power by popping fuses/holders, make sure they don't "arc" and ruin the holder/catch fire).

    Of course, with a battery bases system, the battery+loads have to be high enough to push the controller into "bulk mode" (maximum power transfer from the array).

    Peak typical output from solar panels is around 77% to 82% or so--Unless you have subfreezing weather.

    You say that array orientation does not make much change? That is sort of to be expected... If you are 10 degrees off then Cos(10)=0.98 (98% of available power). Cos(60) degrees off angle = 50% of available power:

    720 watts of panels * 0.80 derating = 576 Watts typical maximum
    576 watts / 720 watts = 0.8 -- 80% of expected maximum (roughly)--Is it a very clear day near noon time?
    Cos-1( 0.8 ) = 37 degrees off angle (are you measuring power with that much "off angle"?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • solarix
    solarix Solar Expert Posts: 713 ✭✭
    Re: Does Outback CC shut off at 145v to protect itself?

    The problem with CC input voltage is if for some reason the array has been disconnected and then you go to reconnect it on a clear cool day, the Voc could be too high and zap the controller before it even starts operating. The good news (as I understand it) is that the Midnite 150V input spec is figured on top of the battery bank voltage as it is relative to B+. So with a 48Vnom battery, the array can go nearly to 200V. Correct me if I'm wrong...
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Does Outback CC shut off at 145v to protect itself?

    Here is an "Official" HyperVOC document from Midnite:

    http://www.midnitesolar.com/pdfs/whyHyperVOC.pdf

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    Re: Does Outback CC shut off at 145v to protect itself?

    As we are speaking of MPPT CCs, the loading on the PVs is produced by the Buck Converter running. When there is too little PV input power to make sense to run the Converter the CC shuts if off, as it requires roughly 5 - 10 watts just to make the Converter run.

    In very low light, the CC rests or sleeps with the converter off. Early in the morning, before sunrise (usually) the ambient temperature is at its lowest, and the CC is still sleeping -- no load on the PVs, so the PV string voltage is at Voc for the temperature of the PVs. Under these conditions, there is on sun striking the PVs, so there is not enough power to run the MPPT Converter.

    If the Voc is too high, 145 + volts, the CC will try to protect itself, by continuing to sleep/rest. This means that there is no load on the PVs, and with the high input voltage, the CC will continue to produce NO power until the PV temperatures decline to a value below the high voltage shutoff point. This could take some time. So high string voltages, with cold temperatures can mean that the system will avoid producing power, while the CC WAITS for the temps to decline -- this is power wasted, compared to a system that uses a lower, more reasonable string voltage.

    With strings of six 17.X-ish Vmp PVs, the STC (25 degree C PV Cell temps), the string Vmp would be about 106 V, and the string Voc would exceed 125 V. At colder temperatures, this Voc will rise.

    Again, usually, the highest Voc will be before sunrise, on cold mornings (this means that there will be NO sun striking the PV cells at all). Your CC will show the Highest Voc to date in the Logs, somewhere.

    FWIW, we run strings of three real 24 V PVs -- 35.4 Vmp + 106 Vmp string voltage. The highest recorded Voc is now 141 V on one system, in our moderate climate, over a ten year operating history.
    These high string voltages redice CC efficiency a bit, and make the CC run hot. Even in the Summer, in Float with light loads, the Vin to the CC can approach 120 V, this results in considerable CC heating, even at low output currents.

    Strings of five (as have been proposed in the past, IIRC) would be considerably better, except that your total number of PVs is not evenly divisible by five, with no remainder .. and so on. FWIW, YMMV, 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.
  • softdown
    softdown Solar Expert Posts: 3,812 ✭✭✭✭
    Re: Does Outback CC shut off at 145v to protect itself?

    I am partial to this graphic explanation of Hyper VOC induced by cold weather. Midnite CCs are better than Outback CCs at handling Hyper VOCs. A Hyper VOC meltdown voids the warranty. Who would have suspected that your CC could die before the sun rises?

    http://www.midnitesolar.com/pdfs/whyHyperVOC.pdf
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Does Outback CC shut off at 145v to protect itself?
    softdown wrote: »
    I am partial to this graphic explanation of Hyper VOC induced by cold weather. Midnite CCs are better than Outback CCs at handling Hyper VOCs. A Hyper VOC meltdown voids the warranty. Who would have suspected that your CC could die before the sun rises?

    http://www.midnitesolar.com/pdfs/whyHyperVOC.pdf

    Technical point: only MidNite charge controllers have the HyperVoc function.
    The other makers expect you to have brains enough to plan your array properly to begin with.

    And before anyone starts, there are plenty of other brand controllers operating up here in Really Cold Land without any issues.

    There is usually no reason whatsoever to design an array whose Voc would come close to the V max in of 150 found on most charge controllers. When long distances are involved making such high Voltage arrays a necessity, use the right controller that can take these high inputs. Even if that means one of the hyper-expensive 600 Volt ones from Xantrex or Morningstar.

    THINK BEFORE YOU BUY, PLAN BEFORE YOU BUY.
  • Dan_
    Dan_ Solar Expert Posts: 61 ✭✭✭✭
    Re: Does Outback CC shut off at 145v to protect itself?

    Complicated to explain but its a temp setup right now so some things not ideal. Will eventually go to strings of 5 especially since now one panel cracked. I'll keep the other 3 as spares

    Don't have a current clamp meter unfortunately, might be in the market now. Tested voltage again though and this time oddly two panels show 7v while others are 16v. I put in a known working panel (since I have extras) and same thing. What the heck is this about? Just when I start thinking I'm not clueless about this stuff...


    Max voltage since setup 44 days ago was 127v. Peak power was 700w. Clear sunny last 2 days: 410, 430.
  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    Re: Does Outback CC shut off at 145v to protect itself?

    Hi Dan,

    Well, you probably know that Kyocera did make some PVs eight or ten years ago, that had a number of Field Failures, which they were very good about replacing under Warranty.

    Low output was the symptom.

    A quick search did find this ... :
    http://forum.solar-electric.com/showthread.php?5258-Defective-Kyocera-solar-panel

    A Clamp DC Ammeter should be a big help. Radio Shack used to sell one, that is similar to the Sears one, and those both work well and are $50 - 60.

    It can be difficult to measure the voltage of individual PVs in a string, in an operating system, but that info would be important. Parallel strings affect the string voltages of other strings.

    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.
  • Dan_
    Dan_ Solar Expert Posts: 61 ✭✭✭✭
    Re: Does Outback CC shut off at 145v to protect itself?

    Previous owner had all the panels replaced under warranty. These panels are 2012 remanufactured.

    Is it normal for individual panels to have low voltage in a string under working condition? Its not the panels since they were swapped but still act weird

    Thanks very much for yours and everyone's replies
  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    Re: Does Outback CC shut off at 145v to protect itself?

    Hi Dan,

    BTW, fine on your maximum high Voc to date, hope that you will be OK, until you install the final configuration.

    You either have some severe connection issues, or, the individual PVs SEEM to contribute in a very unequal fashion to the power of each string.

    You may want to test each string individually, with the breakers for all other strings off. At least, this would let you test each string separately.

    If you could possibly buy or borrow a Clamp DC Ammeter, this should be a big help in diagnosing the issues.

    If you look at the link that other Thread, BB Bill suggested a good way to test each PV module, using a standard DMM ... just be careful to move the test leads as required for your meter. 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.
  • Dan_
    Dan_ Solar Expert Posts: 61 ✭✭✭✭
    Re: Does Outback CC shut off at 145v to protect itself?

    Right now its a single string of 6 panels. 12ga wire. No idea how I could screw up the connection but I suppose its possible.

    Its safe to short a panel with a digital ammeter with it still connected in series, yes?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Does Outback CC shut off at 145v to protect itself?

    Yes, it can be OK to short a panel (or string of panels). However, you need to make sure your maximum current on the amp meter is within range (typically 10 amps max), and that you are careful with the connections (MC4 connectors should not "arc" when making/breaking connections--Covering the panels can help or make connection elsewhere).

    However, if you have only one string, then the meter on the charge controller should be "good enough" (if your controller has one).

    Vmp-array and Imp-array. And Vbatt with status of the charge controller (bulk, absorb, float, etc.) to figure out if the controller is pulling maximum current or not.

    There is really no reason to measure Isc (or Isc-array) on a single string. It is not going to tell you much more.

    You still might want to get a DC Current Clamp Meter (like this one from Sears) if you want to confirm the various current in the system. Very handy for debugging/understanding power systems.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Does Outback CC shut off at 145v to protect itself?
    Dan_ wrote: »
    Right now its a single string of 6 panels. 12ga wire. No idea how I could screw up the connection but I suppose its possible.

    Its safe to short a panel with a digital ammeter with it still connected in series, yes?

    That depends on what you mean.
    One panel out of a string with a DMM across it to measure Amps is not a problem so long as the string isn't connected to anything.
    If it is connected then the DMM can receive current generated by the other panels as it is essentially a parallel path around the one panel. Don't do that if there is the possibility of the current being greater than what the meter can handle (i.e. parallel PV connections). Even if not the reading may be quite inaccurate due to the other current inclusion.

    In other words if you want an accurate test you disconnect everything except what you are testing.
  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    Re: Does Outback CC shut off at 145v to protect itself?

    And, Dan, one further thing;

    It is also important to open the breaker that feeds the PVs into the CC BEFORE you try measuring Isc with the DMM. If you do not disconnect the PV input, the MX-60 could be damaged.

    So, open the MX-60's input breaker and measure the Isc at the input terminal of the that input breaker, or perhaps measure it closer to the PVs.

    FWIW, 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.