Help choosing a charge controller

faccnator
faccnator Registered Users Posts: 35 ✭✭
edited July 2018 in General Solar Power Topics #1
Hey all. Been reading for a long time. First post.

Looking for a charge controller suggestion.

I have 7ea Renogy 270w panels coming and I am trying to choose a charge controller. I have a 24 volt battery bank.

I am drawn to the Schneider electric products but I’m not sure if their charge controllers are worth the price.

Any suggestions? I use an old Xantrex SW4024 with an Outback Autotransformer for 240v. To this point I have only been using it for backup.

I’m in Florida.

Thanks again!
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Comments

  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    edited July 2018 #2
    Quick, Buy one more panel or send 1 back...

    7 is a very ugly number for panels. It's prime so you can run them all in parallel, which you can't because the voltage is to low or you can run a single string of 7 panels, which would require a high voltage charge controller which will cost big bucks. Hopefully you are in south Florida and are buying the panels from Sun Electric in Miami and can just go down and pick up 1 more panel and run 4 strings of 2 panels. Though I haven't seen any Renogy panels there in quite a while.
    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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  • faccnator
    faccnator Registered Users Posts: 35 ✭✭
    #3
    Actually 6 will fit perfect on my unobstructed southern elevation so I will return one. Thank you. Does that help with suggestions? I was initially going to install them in series to keep the wire size down but I think you are suggesting not to due to high voltage. I’m trying to pick my poison
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  • faccnator
    faccnator Registered Users Posts: 35 ✭✭
    #4
    Also they are 24volt panels
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #5
    We don't know the specs on your panels, they could be 60 cell panels for a vmp of around 30-32volts and a VOC of around 38 volts, or they could be 72 cell panels with a VMP of around 35-38 and a VOC of around 45 volts

    Either case would put the VOC of a string of 6 panels above the safe operating range of most charge controllers. 6x38=228 volts and 6x45=270 volts. Only reason to run them in a single long string and pay the price for a high voltage charge controller would be if they will be a long distance from the charge controller.

    Lots of good choices, you will have an array of  270 x 6= 1620 watts so an effective potential of about 1620/29=56 amps, so pretty much any 60 amp or higher charge controller would work.

    I have used Midnite Classics and like them, you can create triggers to turn on loads once it reaches a certain point in it's charging. It will also leave you some room for expansion being able to handle around 94 amps depending on configuration. Schneider makes good products. As does Morningstar and Outback.

    Midnite Classic (about 92 amp at 24 volts) $550;
    https://www.solar-electric.com/midnite-solar-classic-150-sl-charge-controller.html

    Outback FM80 (80 amps) $500 (requires addition equipment for some programing);
    https://www.solar-electric.com/outback-power-flexmax-fm80-150-mppt-charge-controller.html

    Morningstar MPPT 60(60 amps), $550;
    https://www.solar-electric.com/motr60ampmps.html

    Schneider Conext MPPT 60(60 amps), $546;
    https://www.solar-electric.com/xaxwmp60amps.html


    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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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #6
    Forgot to say, so you can run them as 2 strings and combine at the panels and make 1 run to the charge controller. You would loss a bit due to the higher conversion (from high voltage to 24 volts) but it wouldn't require a combiner box and fuses or breakers.  

    ...Or you could run 3 strings of 2 panels, which would allow the charge controllers to run more efficiently but require a combiner box at the panels. 
    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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  • faccnator
    faccnator Registered Users Posts: 35 ✭✭
    #7
    Gosh I just can’t thank you enough for the info. I hope that soon I have something to contribute. Here are the specs on the panels.


    Specifications
    Maximum Power: 270W Maximum System Voltage: 1000 VDC (UL)
    Optimum Operating Voltage (Vmp): 31.40V Open-Circuit Voltage (Voc): 38.60V
    Optimum Operating Current (Imp): 8.60A Short-Circuit Current (Isc): 9.03A
    Maximum Series Fuse Rating: 15A Weight: 42.8lbs
    Dimensions: 64.96 x 39.25 x 1.57 inch


    How do I decide the wiring configuration that is right for me? How many panels in a string?
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #8
    I'll second the 3 strings of 2 panels.  Needs more copper for the higher panel amps, but runs the charge controllers in a more favorable voltage ratio.   You will want a combiner / breaker panel anyway, so you can easily do troubleshooting  and such.
    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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  • faccnator
    faccnator Registered Users Posts: 35 ✭✭
    edited July 2018 #9
    Ok so last question for tonight. Maybe. If I go with the 3 strings of 2 panels. What size wire do I need from the combiner to the charge controller? Approximately 20 feet
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #10
    At 20', strings of 2 are likely a good choice.

    You can look at voltage drop for different wire sizes at
    https://www.calculator.net/voltage-drop-calculator.html
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #11
    Photowhit said:
    We don't know the specs on your panels, they could be 60 cell panels for a vmp of around 30-32volts and a VOC of around 38 volts, or they could be 72 cell panels with a VMP of around 35-38 and a VOC of around 45 volts

    Either case would put the VOC of a string of 6 panels above the safe operating range of most charge controllers. 6x38=228 volts and 6x45=270 volts. Only reason to run them in a single long string and pay the price for a high voltage charge controller would be if they will be a long distance from the charge controller.

    Lots of good choices, you will have an array of  270 x 6= 1620 watts so an effective potential of about 1620/29=56 amps, so pretty much any 60 amp or higher charge controller would work.

    I have used Midnite Classics and like them, you can create triggers to turn on loads once it reaches a certain point in it's charging. It will also leave you some room for expansion being able to handle around 94 amps depending on configuration. Schneider makes good products. As does Morningstar and Outback.

    Midnite Classic (about 92 amp at 24 volts) $550;
    https://www.solar-electric.com/midnite-solar-classic-150-sl-charge-controller.html

    Outback FM80 (80 amps) $500 (requires addition equipment for some programing);
    https://www.solar-electric.com/outback-power-flexmax-fm80-150-mppt-charge-controller.html

    Morningstar MPPT 60(60 amps), $550;
    https://www.solar-electric.com/motr60ampmps.html

    Schneider Conext MPPT 60(60 amps), $546;
    https://www.solar-electric.com/xaxwmp60amps.html


    Morningstar and Schneider are passively cooled, no fan noise, Midnight and Outback have fans, all good controllers just something to consider.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • Raj174
    Raj174 Solar Expert Posts: 795 ✭✭✭✭
    #12
    With 3 strings of 2, the cable run from combiner to the controller will have 62 volts at about 26 amps on it.
    4480W PV, MNE175DR-TR, MN Classic 150, Outback Radian GS4048A, Mate3, 51.2V 360AH nominal LiFePO4, Kohler Pro 5.2E genset.
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #13
    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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  • faccnator
    faccnator Registered Users Posts: 35 ✭✭
    #14
    Everyone thank you so much for showing me how to use the tools and calculators. I’ll give everyone an update when they are up and running. Thanks again.
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