PWM Charge Controller adjust for voltage drop?

Mike at Energy Commission
Mike at Energy Commission Solar Expert Posts: 50 ✭✭✭✭
in Off Grid Solar & Battery Systems #1
Current setup is 4 - 100 Watt 12v panels, Xantrex C40 CC (from NAWS) and 2- 6v batteries in series a cheap 1100 Watt 12v MSW inverter. I run the panels parallel to get a nominal 20 Amps. I found a nice spot in a field next to my condo to place the 4- panel array that can get me an additional 3 hours of good sun. Problem is, it would be about 25 ft from the closest panel in the string to the batteries. I can place the Charge Controller at battery location or array location. I am considering running #6 wire for 25' and crossing my fingers hoping it will work. Does the PWM CC adjust for any voltage drop? In this situation what is the best place for the CC? Would like to do this without converting to 24v system.
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #2
    Re: PWM Charge Controller adjust for voltage drop?

    Put the CC near the battery. 25 ft one way = 50 ft round trip. 50 ft of #6 cable will result in a loss of 8 watts when you have 20 amps of current flowing. There will be much less loss at lower current flow.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: PWM Charge Controller adjust for voltage drop?

    A PWM controller can not compensate for Voltage drop.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #4
    Re: PWM Charge Controller adjust for voltage drop?

    If you had a good MPPT controller you could wire your panels in either two parallel strings, or if the distance was greater, in one series string and send higher voltage, lower amperage power back to the controller at the batteries, resulting in a relatively very small power transmission line loss. The MPPT controller would then act as a DC transformer, taking that high voltage, automatically down converting the voltage to match what the batteries require, and giving you back the amps.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: PWM Charge Controller adjust for voltage drop?

    Right now there aren't any MPPT controllers available in the 20+ Amp range. Using two smaller ones or one larger one is a lot of money spent.
    We're still waiting on Rogue and mini-MidNite.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #6
    Re: PWM Charge Controller adjust for voltage drop?

    http://www.solar-electric.com/motr60ampmps.html
    and
    http://www.solar-electric.com/oufl80sochco.html
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  • Mike at Energy Commission
    Mike at Energy Commission Solar Expert Posts: 50 ✭✭✭✭
    #7
    Re: PWM Charge Controller adjust for voltage drop?
    waynefromnscanada wrote: »
    http://www.solar-electric.com/motr60ampmps.html
    and
    http://www.solar-electric.com/oufl80sochco.html
    yes indeed, that is my next move, as funds allow, even though my Xantrex C40 is working like a fine tuned swiss watch. about my OP I am going to do some experiments with different lengths cables, take some measurements and see how it all works out.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #8
    Re: PWM Charge Controller adjust for voltage drop?

    Didn't some of the old TRACE controllers have remote voltage sense ??
    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

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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