Too much wattage from panels to Flexmax60 charge controller?

Skipmca
Skipmca Registered Users Posts: 18 ✭✭
in PV Installers Forum - NEC, Wiring, Installation #1
I'm installing 6-370 watt panels in parallel to my Flexmax60 charge controller.  Is that too much wattage for that controller?
SkipMcA
South Park, Colorado
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #2
    Should be;

    No problem for a 48 volt system...

    Close for a 24 volt system...

    Too much for a 12 volt system...

    When in doubt consult your manual;

    Microsoft Word - 900-0009-01-00 Rev D.docx (outbackpower.com)
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,886 ✭✭✭✭✭✭
    #3
    You are fine ! Typical to over panel by 20% so 2,400 watts nameplate solar would be the max in a hot climate.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • Skipmca
    Skipmca Registered Users Posts: 18 ✭✭
    #4
    Thanks Photowhit and Dave.  I have that chart.  That is why I asked.  Seemed like quite a bit more than reasonable.  I now have two sets of panels. 6-320 watt and 6-370 watt. Switching from the 320s to the 370s temporarily until I can install an additional cc (a flexmax80). Also going to reconfigure batteries for 36v.  I would change to 48v, but I have 12-6volt batteries. 
    SkipMcA
    South Park, Colorado
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #5
    Skipmca said:
    Also going to reconfigure batteries for 36v.  
    Not a lot of 36 volt inverters or applications...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • Skipmca
    Skipmca Registered Users Posts: 18 ✭✭
    #6
    I had a feeling there was a reason not to do 36! Thanks.
    SkipMcA
    South Park, Colorado
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #7
    Skipmca said:
    I'm installing 6-370 watt panels in parallel to my Flexmax60 charge controller.  Is that too much wattage for that controller?


    Hi Skip..,

    Well,  like so many things,   it really all depends on the EXACT specs of the PVs.    Assume that you have a 24 V system,  still.

    BUT,  the OB FM60 and FM80 have a Maximum total PV  Isc spec  --  80% of the output current rating.   For the FM60,  this is 48 A total for the sum of the Isc  rating of each string,   or of each PV,  it the PVs are singles,  all in parallel.

    What is the manufacturer and model number of the 370 Watt PVs that you would be using?

    Thanks,   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.
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  • Skipmca
    Skipmca Registered Users Posts: 18 ✭✭
    #8
    Hello Vic: Thanks for replying.  Yes, 24 volt system.  Here are the panel specs:


    SkipMcA
    South Park, Colorado
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,886 ✭✭✭✭✭✭
    #9
    You should really just consider 48v and recycle/repurpose the other batteries.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • Skipmca
    Skipmca Registered Users Posts: 18 ✭✭
    #10
    "You should really just consider 48v and recycle/repurpose the other batteries."

    Hello Dave: Do you mean do one string of 8 batteries for 48v?  I would still have adequate power with that setup.  They are Rolls L16s at 428ah.  
    SkipMcA
    South Park, Colorado
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,886 ✭✭✭✭✭✭
    edited February 2021 #11
    Definitely yes ! A fine battery for a 48V inverter/charger. For many people living in a home, a 400+ AH bank at 48v is all they need. Use of an Outback inverter will allow you to network the system.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #12
    Skipmca said:
    Hello Vic: Thanks for replying.  Yes, 24 volt system.  Here are the panel specs:



    Hi Skip,

    Re  your original question,  the total maximum Isc for six of those PV all in parallel,   is 59 Amps.   The Limit for the OB FM60 is  48 Amps,  so,  the proposed configuration results in excessive total PV Isc.

    Strings of two of the PVs  should be OK,  as that halves the total Isc (29.5 A).

    OR,  an FM80 (64 A total max Isc rating)  should be OK with all six PVs in parallel.

    The way I see it,  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.
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  • Skipmca
    Skipmca Registered Users Posts: 18 ✭✭
    #13
    Thanks Vic.  I'm proposing to hook up 5 of the panels, so the total amps would be 49.  Also, the wattage would be 15% over recommendation.  Does that sound ok?
    SkipMcA
    South Park, Colorado
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #14

    Skip,

    Well, five of the 370 W PVs on an FM60 is certainly less-risky than are six.

    It would probably be OK,  in most situations,  but,  still a bit over-spec on the max PV power.   Would worry less about being about 2% over the total max Isc.

    Your decision.   Good Luck,  picking nits,  over for now.    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.
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  • Skipmca
    Skipmca Registered Users Posts: 18 ✭✭
    #15
    Thanks Vic.
    SkipMcA
    South Park, Colorado
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