panel parallel and series wiring help

larrybc1
larrybc1 Solar Expert Posts: 44 ✭
in General Solar Power Topics #1
Hi..I have 16 evergreen 210 watt panels with the following specs:
Vmp 18.3
Voc 23.1
Imp 11.48 A
Isc 12.11 A

Can I put these panels 4 in parallel and then 4 in series..I was going to get 4 more panels but having trouble finding any now..

If that wont work can I just leave them 4x4 and then get some different panels and use a seperate charge controller? thks for the help..Larry
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: panel parallel and series wiring help

    What kinds/rating of Charge Controller (MPPT/PWM), and what is the battery bank voltage?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: panel parallel and series wiring help

    Also, you want to make four strings of four in series, then connect the strings in parallel.

    That would give you an array with:
    Voc 92.4
    Vmp 73.2
    Imp 45.92
    Isc 48.44

    This combination should only be used with an MPPT type controller. You might use it on a 48 Volt system with a PWM controller with a small power loss.

    It's a fairly high Imp so V-drop could be a problem over any long distance even with the 73.2 Vmp (counts as a 48 Volt nominal). For example: on a 50' run from array to controller you'd need to use 4 AWG wire to keep the Voltage drop below 3%.
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  • larrybc1
    larrybc1 Solar Expert Posts: 44 ✭
    #4
    Re: panel parallel and series wiring help
    BB. wrote: »
    What kinds/rating of Charge Controller (MPPT/PWM), and what is the battery bank voltage?

    -Bill

    Hi Bill..Just ordered an outback FM80 controller and will be on a 48 volt system..would like to run these 16 panels 4x4 and then get 3 or 4 different panels (hard to match up panel voltage and Vmp) abd run them off a seperate MPPT controller..does this look OK? thks Larry
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #5
    Re: panel parallel and series wiring help

    Should be fine.

    If you can match the Vmp of other series/parallel panels within ~10% or better, then you can share the one controller.

    If Vmp difference is greater than 10%, you would be better off getting a second MPPT controller.

    Always use heavy/short cables and home run a dedicated connection to each charge controller from the battery bank.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • larrybc1
    larrybc1 Solar Expert Posts: 44 ✭
    #6
    Re: panel parallel and series wiring help
    BB. wrote: »
    Should be fine.

    If you can match the Vmp of other series/parallel panels within ~10% or better, then you can share the one controller.

    If Vmp difference is greater than 10%, you would be better off getting a second MPPT controller.

    Always use heavy/short cables and home run a dedicated connection to each charge controller from the battery bank.

    -Bill

    thks bill..was concerned that the Vmp of 18.3 X 4 panels = 73.2 was going to be enough to charge the 48 volt battery bank in hot weather as I will be located in the Phils--temp 22-30 degress C..thks Larry
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #7
    Re: panel parallel and series wiring help

    I've got an array of 15 evergreens,
    304776_191709547569173_120212794718849_447297_639864695_n.jpg wired 5 in series as a string, and then 3 strings. Handles the summer heat, and the MPPT manages the winter chill.
    You would loose 1 panel (use it to keep a 12V battery topped off?), but may gain back some power from less parallel strings/amps
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #8
    Re: panel parallel and series wiring help

    Doing 3x5 (parallelxseries) would probably be nicer... But 30C is not that hot (Philippines or Phoenix?).

    At 30C (full sun, no wind), your array voltage could be as low as 62 volts Vmp-hot... Not great, but should not cause you any issues unless you have a lot of voltage drop in the Array to Charge Controller wire run... What is the length and diameter of wiring you are planning on using?

    If you do, it would be better if you did 3x5 instead of 4x4.

    As always, keep the wire run between the charge controller and the battery bank short and heavy gauge wiring.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • larrybc1
    larrybc1 Solar Expert Posts: 44 ✭
    #9
    Re: panel parallel and series wiring help
    mike90045 wrote: »
    I've got an array of 15 evergreens,
    304776_191709547569173_120212794718849_447297_639864695_n.jpg wired 5 in series as a string, and then 3 strings. Handles the summer heat, and the MPPT manages the winter chill.
    You would loose 1 panel (use it to keep a 12V battery topped off?), but may gain back some power from less parallel strings/amps

    yea looks nice bill..think i will try to find 4 more panels to run 5 in a string then 4 strings..voc would be 116 or so..thks larry
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  • larrybc1
    larrybc1 Solar Expert Posts: 44 ✭
    #10
    Re: panel parallel and series wiring help
    BB. wrote: »
    Doing 3x5 (parallelxseries) would probably be nicer... But 30C is not that hot (Philippines or Phoenix?).

    At 30C (full sun, no wind), your array voltage could be as low as 62 volts Vmp-hot... Not great, but should not cause you any issues unless you have a lot of voltage drop in the Array to Charge Controller wire run... What is the length and diameter of wiring you are planning on using?

    If you do, it would be better if you did 3x5 instead of 4x4.

    As always, keep the wire run between the charge controller and the battery bank short and heavy gauge wiring.

    -Bill

    length of run would be about 40 -50 feet..wht size wire would you suggest? thks
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #11
    Re: panel parallel and series wiring help

    4x4 string, with 18.3 volt Vmp and 11.48 amp Imp. Assume 50' run (1 pair of wires):
    • 4 x 18.3 volts = 73.2 volts Vmp nominal
    • 4 x 11.48 amps = 45.92 amps Imp nominal
    • 3% voltage drop * 73.2 volts Vmp-array = 2.2 volts worst case drop
    • 1% voltage drop * 73.2 volts Vmp-array = 0.73 volts best case drop
    Using a generic voltage drop calculator and trying different numbers, we get:
    • 50' @ 45.92 amps with 2.2 volt drop = 6 awg
    • 50' @ 45.92 amps with 0.7 volt drop = 1 awg
    If you bump it up to 3X5 array:
    • 5 x 18.3 volts = 91.5 volts Vmp nominal
    • 3 x 11.48 amps = 34.44 amps Imp nominal
    • 3% voltage drop * 91.5 volts Vmp-array = 2.7 volts worst case drop
    • 1% voltage drop * 91.5 volts Vmp-array = 0.915 volts best case drop
    Using a generic voltage drop calculator for the 3x5 array and trying different numbers, we get:
    • 50' @ 34.44 amps with 2.6 volt drop = 8 awg
    • 50' @ 34.44 amps with 0.7 volt drop = 3 awg
    Those are the rough numbers I get...


    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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