12V vs 24V vs 48V

System
System Posts: 2,511 admin
in General Solar Power Topics #1
What are the advantages of the higher voltage systems? I know that the wire to connect things is not as critical but I also have several items that already use 12VDC which I figure I can't use on a 24 or 48 V system without tapping into signal batteries that might upset the balance of the string.

TIA,
tsp
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
    Re: 12V vs 24V vs 48V

    If you have a lot of 12V appliances, then I would stick with a 12V system.

    If you have a couple of large inverters, and need to run regular household appliances, and feed the inverters from a battery, then 48 (or at least 24V) is the way to go.

    Watts are watts, a 1,000 watts at 12v=83A @ 48V a much more manageable 21A
    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

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  • System2
    System2 Posts: 6,290 admin
    #3
    Re: 12V vs 24V vs 48V

    the higher voltage requires smaller size wire runs. far as 12 volt devices go a branch circuit can run along side the 24 or 48 volt if you can separate the battery bank for those runs. those wire runs are required to be combined on the roof in a box for code. a larger main line than goes to your battery box and control box. if not code than smaller wire can be used for the run to your battery box. the problem is inverters deliver at a set voltage and two different output voltages can make a recharging conflict.
    jam
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #4
    Re: 12V vs 24V vs 48V

    And you are correct about battery balancing--do not tap into a 12 volt battery in a 24/48vdc string. The battery you tap will either be undercharged, or the rest of the string will be overcharged... Either way, one or more batteries will have their lives cut short.

    Only way to get 12 volts out of a higher voltage string is a separate system, using a 24/48 DC to 12 vdc converter, a 24/48 to 12 vdc charger, or even an inverter to 12 vdc converter... Your choice.

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