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Advantages / Disadvantages

Discussion in 'Photovoltaics' started by sunnybouy60, Jan 16, 2006.

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  1. sunnybouy60

    sunnybouy60 Guest

    Hello everyone, could someone explain the advantages / disadvantages of 12v
    vs. 24 or 48v setups?
  2. Steve Spence

    Steve Spence Guest

    The higher the voltage, the smaller the wiring for a given wattage.
    typically large installations use 48vdc, medium use 24vdc, and small
    ones use 12vdc.
  3. I'm no expert but my understanding is that higher voltages mean
    less loss of power in long runs of wires, higher capacity battery
    banks using smaller cells and inverters using slightly less
    expensive parts.

    That is to say, if you run 1000 feet of wire and pump 12V through
    it then you'll lose more power than if it were 48V. If you need
    a total storage capacity of 1000 watt-hours then you could do it
    with (1000Wh/12V) 83 Amp-hours of batteries but at 48V it would
    only require (1000Wh/48V) 20 Amp-hours. So, if you wanted to do
    either of these with 20 Amp-hour batteries the first (12V) would
    require 4 in parallel and the second (48V) would require 4 in
    series. Series works better. Also, some inverters use essentially
    the same parts for 12V and 48V but the 48V version will put out
    4 times the power.

    Unfortunately, there are a heck of a lot more 12V appliances and
    lights than 48V (or even 24V) versions. If you want to run things
    without using an inverter then 12V has this advantage.

  4. Richard P.

    Richard P. Guest

    Well, as some of the others have mentioned, the line loss is lower on the
    higher voltages. But I also believe there is increased inverter and battery
    charger efficiency with the higher voltage input.
  5. George Ghio

    George Ghio Guest

    12 Volt - to 1000 Wh
    24 Volt - 1000 to 2000 Wh
    48 Volt - 2000 and up

    These figures can overlap by as much a 100%

    12V 1000W = 83A
    6-2v Cells @ X Ah

    24V 1000W = 42A
    12-2V Cells @ 1/2 X Ah

    48V 1000W = 21A
    24-2V cells @ 1/4 X Ah

    12V lots of consumer goodies, lights, appliances to choose from

    24V less consumer goodies, lights, appliances to choose from

    48V not many consumer goodies, lights, appliances to choose from

    It comes down to what you want to do. If you want to run an average
    house as you would in the city, as in 10+ kWh a day with all the
    consumer goodies you can lay your hands on, 48V is the way to go.

    If you prefer the minimal lifestyle and only need 1 to 2 kWh a day you
    can do it with 12V.

    24V fits in between as you may choose.
  6. sunnybouy60

    sunnybouy60 Guest

    If you are using a 48v inverter the appliances that you can run aren't
    affected right? It's still being changed to 120vac. Also do higher voltages
    perform better than 12v in extreme warm weather? ie. Southern Arizona.
  7. Blue Cat

    Blue Cat Guest

    Yes, but the effect is from the resistance of the conductors, which
    increases with rising temperatures. Using a higher voltage decreases power
    losses from conductor resistance.
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