Line Distance for power Max able to run on 12v system?

Arizona Son
Arizona Son Registered Users Posts: 3
What is the longest distance from the solar panel to the batteries can I run a line on a 12v system?

Comments

  • jcheil
    jcheil Solar Expert Posts: 722 ✭✭✭
    Re: Line Distance for power Max able to run on 12v system?

    That literally depends on the size of the wire.

    However, there is a point in which it is cheaper to spend $600 on a controller that allows high voltage using smaller wires rather than simply the investment in a larger sized wire.

    Maybe someone could figure out where that "point" is?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Line Distance for power Max able to run on 12v system?
    What is the longest distance from the solar panel to the batteries can I run a line on a 12v system?

    It's not as simple as that. What you're referring to is the power loss due to Voltage drop over distance. There are four factors here: the Voltage at the beginning of the run, the current being supplied, the size of the wire, and the length of the run. As such you need to use a Voltage drop calculator to determine just how much loss there will be.

    An example:http://www.powerstream.com/Wire_Size.htm

    If you use 12 Volts, 20 Amps, and 10 AWG wire you find that in only 10 feet the Voltage drop becomes >3%, which is undesirable. If you increase the wire size to 8 AWG the drop becomes 2% which is fine.

    This is one reason why low Voltage systems benefit from MPPT controllers: with the array Voltage higher (converted to proper charging Voltage by the controller) the current is lower for the same power and thus the resistive effect of the wiring results in less power loss.

    For example if you adjust the above numbers to 24 Volts, 10 Amps (same amount of power) on 10 AWG the wire run can be 40 feet before the same >3% Voltage drop occurs.
  • Arizona Son
    Arizona Son Registered Users Posts: 3
    Re: Line Distance for power Max able to run on 12v system?

    I see. Thanks for the input. So basically going a 24v system is better for say solar panels mounted out in yard with a long run to the garage where the batteries are. Then convert down to 12volts from batteries to use 12v equipment.
  • jcheil
    jcheil Solar Expert Posts: 722 ✭✭✭
    Re: Line Distance for power Max able to run on 12v system?
    I see. Thanks for the input. So basically going a 24v system is better for say solar panels mounted out in yard with a long run to the garage where the batteries are. Then convert down to 12volts from batteries to use 12v equipment.

    The best way is to use a higher voltage controller which can convert to whatever your battery voltage is. And unless it is a very small system and you never plan to upgrade (famous last words) then don't bother with 12v, start at 24v.
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Line Distance for power Max able to run on 12v system?

    To be more precise, you would put your, (eg 12 V panels) panels in series, say 4 of them, and send ~ 17Vmp x 4 = 68V over that long distance wire and let the MPPT Charge controller do its magic and output 24 or 12 V (nominal voltage)
     
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