mppt charger controller max pv volt

robocop
robocop Registered Users Posts: 118 ✭✭
in Solar Beginners Corner #1
Hi everybody

have  4000w power inverter  48vdc /120vac and a 60a  150v max pv  mppt controller .

installed 3  500w panel in series but now the pv is 170v 

think it will damage   the mppt charger or not 

need  some advice 

Thnkss

Bob

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  • SumPower
    SumPower Registered Users Posts: 61 ✭✭
    #2
    Damage? Yes
    The controller will likely protect itself and not allow any DC Current (power) from the solar panels through it above the 150 Volts.
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  • robocop
    robocop Registered Users Posts: 118 ✭✭
    #3
    should i put the panels in parallel instead of in series? or use only 2 panels instead  of 3 ?
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  • robocop
    robocop Registered Users Posts: 118 ✭✭
    #4
    forget something: what type of cable to be used from the controller to the batteries?

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  • SumPower
    SumPower Registered Users Posts: 61 ✭✭
    edited December 2023 #5
    SumPower said:
    Damage? Yes
    The controller will likely protect itself and not allow any DC Current (power) from the solar panels through it above the 150 Volts.

    I should have said that the controller would "try" to protect itself. Typically any voltage over the max can damage it. If you are in snow country where it gets well below freezing, then the voltage from the panels can get higher the colder it gets. So it is important to know what the typical coldest temp is for your area.

    Yes, Parallel to reduce the voltage ouput from the panels to a voltage less than the controller max.

    Any conductor rated for at least 75° C can be used. THHN/THWN

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  • robocop
    robocop Registered Users Posts: 118 ✭✭
    #6
    I mean what awg cable should be best between mppt  controller and the batteries

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #7
    Robocop is on an island in the Caribbean, just off the north coast of Venezuela.

    Curaçao

    What are the panel's specifications (Vmp/Voc/Imp/Ioc)?

    The MPPT solar charge controller uses transistors as switches--Exceeding their 150 Volt limit can easily cause the transistors to fail, and on some (few/many/all?) MPPT controllers, they can log the over voltage and void your warranty.

    You live in a warm climate (no snow, minimum temperatures year round of ~25C)... So the Voc rating of the panels will ever increase above specs (Voc/Vmp rise as panel/cell temperatures drop to freezing and below).

    It appears that your panel Voc voltage is on the order of:

    170 Volts Voc-array (?) / 3 panels in series =  around 57 volts Voc

    With a 150 Vpanel input controller and a 48 volt battery bank, the only "workable" solution is to put 2 panels in series for Voc-array ~114 volts.

    For charging your 48 volt battery bank, you need around 72 volts Vmp-array thru 120+ Vmp-array to charge the battery bank. MPPT controllers (almost all) can just "drop" the array voltage to battery bank voltage... They cannot "increase" array voltages below ~65 volts to that needed to run the MPPT controller and charge the battery bank at 58+ Volts...

    For a 60 amp controller charging a 48 volt battery bank (with Vbatt max of ~58 volts for FLA type batteries), the maximum "cost effective" solar array would be:

    60 amps max charging * 58 volts Vbatt charging * 1/0.77 panel+controller deratings = 4,520 Watt array rough "cost effective" maximum solar array

    So, you can run:

    2 * 500 Watts = 1,000 Watt array (2 series * 1 parallel string for 2 x 500 Watt panels)
    4 * 500 Watts = 1,500 Watt array (2 series * 2 parallel strings for 4 panels)
    6 * 500 Watts = 3,000 Watt array (2 series * 3 parallel strings for 6 panels)
    8 * 500 Watts = 4,000 Watt array (2 series * 4 parallel strings for 8 panels)
    10 * 500 Watts = 5,000 Watt array (2 series * 5 parallel strings for 10 panels)

    Note that you could go with a larger array, but you will get "clipping" of controller output current (60 amps maximum current rating) if you go with 5,000+ Watt array (i.e., your 5,000 Watt array will not output its full output on clear/sunny day around solar noon...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #8
    What cable AWG to run depends on your array (2/4/6/8/10 panels) and the distance from array to charge controller/battery bank shed... Longer wire runs need heavier cable to keep to "reasonable" voltage drop from array to charge controller.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • robocop
    robocop Registered Users Posts: 118 ✭✭
    #9
    it is very clear now about the pv voltage.
    But only the cable AWG between the Mppt charge controller and the l lipo batteries .
    Only thing I can say to your people  for you time you take to help others.
    Is Gods blessings
    Bob
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,101 ✭✭✭✭✭
    #10
    You need to series wire only two panels per string. Parallel won't yield high enough voltage for your 48 volt system. I would get one more panel and wire up 2s2p.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • robocop
    robocop Registered Users Posts: 118 ✭✭
    #11
    think will do pair serial and pair parallel as I have one more panel left. As for the cable wire from the mppt controller to the Daly Bms /lipo batteries  what type of wire should I use ? 
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,101 ✭✭✭✭✭
    #12
    Hopefully, this is what you are referring to. This is 2s2p.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • robocop
    robocop Registered Users Posts: 118 ✭✭
    #13
    more clearer it cant be thnks
    As for the cable wire from the mppt controller to the Daly Bms /lipo batteries  what type of wire should I use ? 

    i mean this is for  the cable to the LIPO batteries  from the MPPT controller

    regards
    Bob
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  • SumPower
    SumPower Registered Users Posts: 61 ✭✭
    edited December 2023 #14


    robocop said:
    I mean what awg cable should be best between mppt  controller and the batteries

    You can use this Voltage Drop Calculator to determine your wire size. 
    Edit: See BB post below for Voltage Drop.


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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #15
    Between any charge controller, and the battery bank... The suggested maximum voltage drop (at maximum charging current):

    12 volt bus: 0.05 to 0.10 volt maximum drop
    24 volt bus: 0.10 to 0.20 volt maximum drop
    48 volt bus: 0.20 to 0.40 volt maximum drop

    Keeping the maximum voltage drop (at max charging current) gives the charger the (close to) actual battery charging voltage--Fast charging, accurate charging....

    Too much voltage drop, the charger will cut back on charging current early and slow down the charging (longer time to charge bank).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • robocop
    robocop Registered Users Posts: 118 ✭✭
    #16
    HI  guys how are you today you are helping a lot

    A next question about solar panel in parallel, my mppt controller is 60a  and 150v max input.

    using 2   500w panel in parallel  will raise or add the Amp but will it dame the controller or what is the max amp input for these  60a controller?

    thnks agian and regards

    Bob
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