adding extension to cottage

System
System Posts: 2,511 admin
in Advanced Solar Electric Technical Forum #1
My first post.  This is a great forum.  I have cottage grown my 24V solar system over the past 3 years.  The wiring is a mixture of 10 and 12 AWG dependent on distance from the batteries.

I now want to add a 16x20 extension at the opposite end of the cottage from the batteries (extension would start 30' from batteries)

q1.  I was thinking of running a 8 AWG from the batteries to the extension and then have a 24V - 12V step down converter and small panel box.  I would then run 10/12 AWG in the extension for the lights.  comments?

q2.  my six 12V batteries are in series and parallel.  (1 +2) + (3 +4) + (5 +6).  All external connections are thru + on battery #2 and - on battery #1.  On some sites I see charge connections on (1 +2) and load connections on (5 +6). comments? 
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Comments

  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #2
    Re: adding extension to cottage

    rojo,
    the wire gage is dependant upon the distance and the current that is to flow. the higher working voltages donnot change the actual voltage drop, but changes the percentage the voltage drop is of the working voltage. i have a link for a voltage drop calculator. this is freeware and is to be used with excel or any similar program. there is a similar program that is downloadable a you'll read in that section.
    http://www.wind-sun.com/smf/index.php?topic=1477.0
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  • System2
    System2 Posts: 6,290 admin
    #3
    Re: adding extension to cottage

    Thanx for the calculator. Since I will be using approx 4 lights (total 5-6 amp), it verifies that I cannot use 12V and 12AWG to run from the stepdown controller, at the batteries to the extension, circuit distance of > 100 ft. I guess I am back to the original idea of 24V and 8AWG to a closet near the extensin and then a stepdown controller and 10/12AWG thru the extension.

    Any ideas on my 2nd question regarding connection to the battery pack?
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #4
    Re: adding extension to cottage

    the better way for your setup may be to take the + from battery 6 and - from battery 1 for charging. the loads can be connected to the + on battery 2 and the - on batterry 5. this helps in balancing the charges and the loads making equalization charges not needed as often. it also prevents too many large connections to the same posts.
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  • AFWnS
    AFWnS Solar Expert Posts: 13 ✭
    #5
    Re: adding extension to cottage

    When you get out that distance, wouldn't it be better to use a small inverter and 110V CF bulbs.
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  • System2
    System2 Posts: 6,290 admin
    #6
    Re: adding extension to cottage
    AFWnS wrote:
    When you get out that distance, wouldn't it be better to use a small inverter and 110V CF bulbs.
    AMEN !! In fact, my battery / solar shed is about 100 feet away from the cottage and a small 400 watt inverter is always on, feeding smaller loads like cf lamps and this computer, through 14/2 cable. Works great. Have another 14/2 run from a dedicated 1000 watt inverter for the "chest fridge" and another 1500 watt dedicated inverter that runs the 1/2 HP 115 volt AC, standard submersable water pump which is 170 feet out in the lake and down deep , where the water is clean and ice cold. The "dedicated" inverters only run when needed by their respective loads.
    Works great!
    Wayne
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #7
    Re: adding extension to cottage

    the inverter idea has merit because even a converter has losses and if you were to up it to 115vac you'd be lowering your wire resistance losses as well. use an inverter to run straight off of the 24vdc. a means of shutting off the inverter conveniently or automatically would be good to eliminate inverter standby power drains.
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