12 volt versus 24 volt

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alcatel99
alcatel99 Registered Users Posts: 31 ✭✭
in General Solar Power Topics #1
Given the same system components batteries and appliance uses how much more efficent will a 24 volt system be over a 12 volt system  approx.
Thanks

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  • New_Mexico_Will
    New_Mexico_Will Registered Users Posts: 107 ✭✭
    #2
    Enough to make it worthwhile.  Your inverter will work a little less, you'll have more equipment options, you can safely use more watts, and you can save a little bit on wiring.
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  • softdown
    softdown Solar Expert Posts: 3,963 ✭✭✭✭
    #3
    I'd go 24 volt if running over 600 watts of panels. Higher voltage is more efficient and allows a superior battery configuration as a rule.  More serial - less parallel. 

    This has been discussed dozens of times in the past. Lots of info on search.

    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
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  • Photowhit
    Photowhit Solar Expert Posts: 6,017 ✭✭✭✭✭
    #4
    I wouldn't go to 24 volt for tiny systems, If you will need more than  220 amp hours at 12 volts, I'd start considering. If you need more than 440 amp hours at 12 volts, I'd go to 24 volts.
    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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  • 706jim
    706jim Solar Expert Posts: 523 ✭✭✭✭
    #5
    One example: The old Trace DR series inverters. 12 volts 3500 watts surge. 24 volts 4400 watts surge.
    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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  • alcatel99
    alcatel99 Registered Users Posts: 31 ✭✭
    #6
    Thanks guys
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  • Holosteric
    Holosteric Registered Users Posts: 1 ✭
    #7
    I will always go with 24v too since it is more efficient since I use more than 440 amp hours at 12 volts.
    ..
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  • alcatel99
    alcatel99 Registered Users Posts: 31 ✭✭
    #8
    Thanks for replies i decided to go with 24 volt one other question i have is there much difference going with 6 volt batteries in series versus 12 volt batteries in series for space considerations 12 volt batteries would work better for me given that i can match the amp/hrs of both i will probably consider 12 volt Deka Batteries.
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #9
    The answer is 6V batteries are generally offered in larger capacity, therefore  larger individual cells which in turn makes the overall cell count lower to obtain an equal capacity, this results in less maintenance and reduces the need for parrallel strings which is not desirable, high Ah 2 volt cells would be the  the best choice in the lead acid world.
    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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