Confirmation needed from all the expert

DarkstormNH
DarkstormNH Registered Users Posts: 48 ✭✭
I called Magnum today to make sure I can wire 4X250 panels straight to the pv bus bar in the magnum mmp panel
I was told this can be done, also i will be using the  magnum cc can handle the 120 volts .
any input please

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Do you have links to the exact controller and solar panels you want to use?

    Series/parallel connections depends on the details of the controller, solar panels, and battery bank (voltage) you want to charge.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • DarkstormNH
    DarkstormNH Registered Users Posts: 48 ✭✭
    BB. said:
    Do you have links to the exact controller and solar panels you want to use?

    Series/parallel connections depends on the details of the controller, solar panels, and battery bank (voltage) you want to charge.

    -Bill
    Bill Thanks for the reply

    the charge controller is from magnum  please see link below
    http://www.solar-electric.com/inverters-controllers-accessories/chco/magnum-energy-solar-charge-controllers.html
    the panels are 36 volts 300 watts
    spec bellow

    CharacteristicsUnitSL6P72-300W
    Maximum Power (Pmax)W300
    Power ToleranceW(0,+5)
    Maximum Power Voltage (Vmp)V36.5
    Maximum Power Current (Imp)A8.21
    Open Circuit Voltage (Voc)V45.10
    Short Circuit Current (Isc)A8.67
    Module Efficiency (ηm)%15.46
    Dimension of modulemm1956*992*40mm(77.0*39.1*1.6inch)
    Pmax Temperature Coefficient%/C-0.42
    Voc Temperature Coefficient%/C-0.3
    Isc Temperature Coefficient%/C0.05
    Maximum System VoltageVDC1000(TUV);600(UL)
    Maximum Series Fuse RatingA15
    Operating TemperatureC-40~ +85
    NOCTC45±2
    STC:1000W/m2.AM1.5 and 25C cell temperature, NOCT : Nominal Operating Cell Temperature

    I know by your calculation I would not have enough panels to charge a 8 t105 24 volts bank
    what I was hoping to do is connect the 4 panel directly to the magnum mmp (pv bus bar)
    and later I would add 2 more panels

    I'm open to your expert guidance thanks


  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    edited November 2015 #4
    I called Magnum today to make sure I can wire 4X250 panels straight to the pv bus bar in the magnum mmp panel
    I was told this can be done, also i will be using the  magnum cc can handle the 120 volts .
    any input please

    the panels are 36 volts 300 watts
    <snip>
    what I was hoping to do is connect the 4 panel directly to the magnum mmp (pv bus bar)
    and later I would add 2 more panels

    From the above quotes, I have no idea what you are trying to do.  Will the CC be seeing 120 volts on its input?  How are you configuring the panels? (series, parallel, or series/parallel).  How will they be configured when you add two more panels?

    If you are putting the 4 panels in parallel, you may barely have enough voltage to charge a 24 volt battery... it might work, the Magnum CC is too new to know for sure.  The problem is that MPPT controllers need more voltage headroom than PWM controllers, and when the panels are hot their Vmp drops.   I would prefer to see you put the 4 panels in a series/parallel configuration with a string length of 2.  When you add 2 more panels, they can be a third string.

    Also, if you are putting the 4 panels in parallel, you must have a combiner box and a circuit breakers for each panel.  If you have 6 panels in three strings as described above, you will need a combiner box and a circuit breakers for each string.

    The requirement for these breakers (or fuses) is an important safety issue.  I suggest that you get a Midnite MNPV3 combiner box with three breakers.  Wire up your 4 panels in two strings, using 2 of the 3 breakers.  When you get 2 more panels, the third breaker is waiting there for them.

    --vtMaps

    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • DarkstormNH
    DarkstormNH Registered Users Posts: 48 ✭✭
    vtmaps said:


    From the above quotes, I have no idea what you are trying to do.  Will the CC be seeing 120 volts on its input?  How are you configuring the panels? (series, parallel, or series/parallel).  How will they be configured when you add two more panels?

    Vtmaps

    Thank you for the post, what I said was I called magnum and asked them if I can wire all four of the panels directly to their
    mmp box using the so called pv bus bar, I was told I could and it would work.
    i wanted to make sure from you guys, yes you are right on the midnight combiner box, i just wanted to avoid that if I could
    i cant so be it I will get it, and wire as you said 2 X2 saving the 3 breaker for later

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Ok--First I have looked at the Magnum MPPT charge controller specifications:

    Specifications:

    Max PV input voltage: 200 VDC + battery voltage, or 240 VDC - whichever is lower
    Max PV operating voltage: 190 VDC
    Max PV array short circuit current: 100 ADC
    Battery voltages: 12, 24, or 48 VDC
    Max output power: 6,600 watts
    Peak efficiency (at full power): >99% (98%)
    Internal cooling: dual ball-bearing fans
    Enclosure type: indoor rated, ventilated, with removable conduit box
    Dimensions: 8.5" x 15.5" x 4.0"
    Weight: 12.5 lbs (5.7 kg)
    Max operating altitude: 15,000 feet
    Mounting: mount on a vertical surface or install on a MP or MMP

    Warranty: 5 years parts and labor

    Looks to be a very nice/capable unit. And running Vmp-array~120 volts looks to be OK (Vpanel-max operating 190 VDC).

    It does not appear that Magnum has a string sizing tool on the web yet.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • zoneblue
    zoneblue Solar Expert Posts: 1,220 ✭✭✭✭
    For a 24V system, the 60 cell panels will not work in a 4P configuration. The other panel you refer to is a 72 cell panel, which will work with PWM controllers but not with MPPT controllers. If you go 4P of the 300W panels you NEED the combiner. IF you go 2S2P, as vt recomended, then you may skip the combiner as 2 strings is safe without one. However a combiner is useful for other reasons, youll end up adding one eventually.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
    http://zoneblue.org/cms/page.php?view=off-grid-solar