Generator to MPPT

Starmoral
Starmoral Registered Users Posts: 13 ✭✭
in Off Grid Solar & Battery Systems #1
I have generator rated 1500W , 24v so I m thinking hooking it directly to 80A MPPT and to 6Kw battery bank. I know it’s been discussed why can and why can’t be done this way,but I wanna know does anyone here actually tried to do something similar? Of course I would like to hear more opinions why this can’t or can work. And what would be best option to implement this generator into my off grid system.
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  • 706jim
    706jim Solar Expert Posts: 520 ✭✭✭✭
    #2
    So you want to hook a generator to a charge controller?
    I thought they were only compatible with DC current.
    Island cottage solar system with appriximately 2500 watts of panels, 1kw facing southeast 1.3kw facing southwest 170watt ancient Arco's facing due south. All panels in parallel for a 24 volt system. Trace DR1524 MSW inverter which has performed flawlessly since 1994. Outback Flexmax 80 MPPT charge controller four 467A-h AGM batteries. Insignia 11.5 cubic foot electric fridge 1/4hp GSW piston pump. My 31st year.
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  • Starmoral
    Starmoral Registered Users Posts: 13 ✭✭
    #3
    Isn’t that on picture bridge rectifier?
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #4
    What is the nominal voltage of the 6kw bank? 24v?

    Is the output of the generator 24vac? Recified to dc?
    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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  • Starmoral
    Starmoral Registered Users Posts: 13 ✭✭
    #5
    Batteries I just ordered they will arrive coming days , but yes that’s the plan, 24.
    I guess it is rectified to dc? Although I can measure ac too on multimeter when I rotate it. What do you think? Here is picture
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #6
    Among other problems, most mppt charge controllers buck higher voltage dc current down to battery charging current. A 24v nominal bank will likely want ~29v absorb charging voltage. An mppt controller would need at least ~ 45v or so.
    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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  • Starmoral
    Starmoral Registered Users Posts: 13 ✭✭
    #7
    Well, yes, but with no load voltage goes up to 40V. So what would you suggest for this rating ?
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  • Starmoral
    Starmoral Registered Users Posts: 13 ✭✭
    #8
    Also is that means that with 12v should work in theory ?
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #9
    I think what you want is a good voltage regulator, not an mppt charge controller. They would be easier to find for 12v, but I think they're available for 24v.
    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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  • Starmoral
    Starmoral Registered Users Posts: 13 ✭✭
    #10
    You mean , generator -rectifier- voltage controller - charge controller -battery ?
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #11
    The regulator is instead of the controller.
    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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  • Starmoral
    Starmoral Registered Users Posts: 13 ✭✭
    #12
    Point some links&examples. What should be power rating of regulator ?regarding rectifier 30A 1000W I have
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #13
    You could start with www.balmar.net

    They make high output alternators and 24v regulators for them.
    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 ✭✭✭✭✭✭
    edited December 2017 #14
    A generator with a bridge rectifier would be in essence a  DC power supply, the output however would not be a smooth DC such as a PV panel, an electrolytic capacitor would smooth the output, which could be used as an input to a MPPT controller, at least according to Morningstar. My advice would be  to ask the manufacturer of the controller you have, if this is possible with your particular controller. See question 3, using a power supply as a substitute for PV panel in the link below.
    http://support.morningstarcorp.com/faq/

    Edit, the open circuit voltage may be 40V but the load voltage will drop, to charge a 24V nominal battery over 30V would be required, preferably higher, this would be a very Inefficient means of charging by the way, as ~80% of the fuel is wasted as heat, the internal combustion engine is not particularly efficient.
    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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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #15
    A generator with only a simple rectifier (4 diode bridge) will have too much Ripple for most charge controllers to manage.

    A MPPT controller expects to see "soft" solar panels, and searches electronically for the MPPT setpoint, and relies on adjusting the PV voltage to control charging.  A generator will never behave like PV panels.
    Some MPPT controllers have preset curves for Hydro or Wind generation, but they also rely on large voltage clippers and loads to help regulate the power, and that would waste fuel on a generator.  Also most turbine gear is multi-phase AC with much less ripple to contend with.

    In short, I don't think you will be happy
    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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  • Starmoral
    Starmoral Registered Users Posts: 13 ✭✭
    edited December 2017 #16
    mcgivor said:
    A generator with a bridge rectifier would be in essence a  DC power supply, the output however would not be a smooth DC such as a PV panel, an electrolytic capacitor would smooth the output, which could be used as an input to a MPPT controller, at least according to Morningstar. My advice would be  to ask the manufacturer of the controller you have, if this is possible with your particular controller. See question 3, using a power supply as a substitute for PV panel in the link below.
    http://support.morningstarcorp.com/faq/

    Edit, the open circuit voltage may be 40V but the load voltage will drop, to charge a 24V nominal battery over 30V would be required, preferably higher, this would be a very Inefficient means of charging by the way, as ~80% of the fuel is wasted as heat, the internal combustion engine is not particularly efficient.
    Thank you, so clearly says on morning star website that MPPT have no issue with this kind of DC. Anyway i would say all of you are talking from theoretical side, no one actually tried to do such thing? So i m gonna try and see ,only way i can know what is going on. Also it is cool idea with electrolytic capacitor as you mentioned ,i will try that too. I let you know everyone how does it go.
    P.S. generator will be powered by pedaling.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,617 admin
    #17
    Ok, you are talking about a peddle powered generator/alternator which is probably ~100-200 Watts maximum. A small MPPT charge controller (for example: 15 amps * 14.5 volts charging ~218 Watts) would be more than large enough for your needs (assuming a single person as a power source).

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