solar array over 200 feet from inverter

ldiorioldiorio Solar Expert Posts: 47 ✭✭
i have been debating weather to install panels on my roof or on the ground ---i have plenty of level land but will have to place the array over 200-250 feet from the inverter( if ground installation)
i understand that with this distance i should be looking at a 48V system

lou

Comments

  • NorthGuyNorthGuy Solar Expert Posts: 1,913 ✭✭
    Re: solar array over 200 feet from inverter

    Ho big is your array? Are you planning on expanding it in the future?
  • ldiorioldiorio Solar Expert Posts: 47 ✭✭
    Re: solar array over 200 feet from inverter

    maybe start with 9 or 12 --230 watt panels --want to keep my options open for growth if needed
    am not restricted by space
    thanks
  • vtmapsvtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    Re: solar array over 200 feet from inverter
    ldiorio wrote: »
    i have been debating weather to install panels on my roof or on the ground ---i have plenty of level land but will have to place the array over 200-250 feet from the inverter( if ground installation)
    i understand that with this distance i should be looking at a 48V system

    Welcome to the forum Lou,

    I will assume this is an off-grid system. You are correct to use a 48 volt system. I will also assume your panels will have a Vmp of 30 volts and an Imp of 7.6 amps.

    If you use #2 wire with 12 panels (4 parallel strings, with 3 panels in series per string) you will lose 2 volts in the cable, representing a 59 watt power loss at full nameplate power. Power loss goes as the square of the power produced, so at half power you will lose 15 watts in the cable.

    If you expand to 5 strings your voltage drop will be 2.4 volts and your max power loss will be 92 watts in the cable.

    To save money, you might want to consider aluminum cable rather than copper.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • tons001tons001 Solar Expert Posts: 71 ✭✭
    Re: solar array over 200 feet from inverter

    I know there has been numerous discussions on using welding/battery wire because of its need for a quality crimp but this company makes some great cable at a great price when you consider the free shipping. Google Temco Industrial Power and check out their welding wire. I also picked up their 11ton hydraulic crimp tool.
  • ldiorioldiorio Solar Expert Posts: 47 ✭✭
    Re: solar array over 200 feet from inverter
    tons001 wrote: »
    I know there has been numerous discussions on using welding/battery wire because of its need for a quality crimp but this company makes some great cable at a great price when you consider the free shipping. Google Temco Industrial Power and check out their welding wire. I also picked up their 11ton hydraulic crimp tool.

    There are so many variables in a solar system as an engineer i find myself thinking more for future capacity than ininatial
    I have a 20KW standby generator to start --hedging to a 48 volt system as the one preferred as i read articles here
    going with a battery backup with Trojan L16RE--240 volt systen bec of my well pump and genny

    considering a XW6048 or GS8048
  • NorthGuyNorthGuy Solar Expert Posts: 1,913 ✭✭
    Re: solar array over 200 feet from inverter

    There are few options on how you can build your system. The biggest difference is the length of the string of panels. For 48 volts, you'll need at least 3 panels per string. So, your options are:

    1. 4 strings of 3 panels. Voc around 110. Imp around 32. Any MPPT controller can do that.
    2. 3 strings of 4 panels. Voc around 150. Imp around 24. You need MN Classic 200 or 250.
    3. 2 strings of 6 panels. Voc around 220. Imp around 16. If you're not in cold climate, Classic 250 can do it.
    4. 1 string of 12 panels. Voc around 440. Imp around 8. The only controller to handle this is XW-MPPT80-600.

    As you can see, as voltage increases, you need more and more expensive controller. But, you will need thinner wire, less MC4 cables, less breakers, and less combiner boxes. You just calculate total expenses for each of these options and you go with what's cheaper.

    Now to wire size. Thicker wire is always better, but it costs more. Thinner wire is cheaper, but it increases heat losses. I made a nice table for you that lists losses in W at 500' length of a cable (250' back and forth). These losses are for full production. Losses for 50% production will be 1/4 of these.
    Wire	Opt.1	Opt.2	Opt.3	Opt.4
    #14	no	no	no	81
    #12	no	no	203	51
    #10	no	288	128	32
    #8	322	181	80	20
    #6	202	114	51	13
    #4	127	72	32	8
    #2	80	45	20	5
    

    You can see that with higher voltage you can get away with cheap #14 wire and have the same losses as with low voltage and expensive #2 wire.

    You also going to have some losses in the controller, which generally increase with the increase of voltage, but also depend on the controller. See the controller docs to make sure that they're acceptable to you.
  • Logan5Logan5 Solar Expert Posts: 32
    Re: solar array over 200 feet from inverter

    If you do this with a High energy array, 150+ DC traveling over AWG6 or better to your "house mounted" charge controller would minimize your loss, you could also consider in a small voltage drop. then you can charge your battery bank in any voltage you set the charge controller to. However a higher main voltage allows for more efficient inverter use. I would not run 48 volts from the array to the house, as the cable needed for anything over 100 feet would be cost prohibitive. 48 volts is "still" low voltage, not good over long distance.
  • icarusicarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: solar array over 200 feet from inverter

    Why not consider a "power house" near the PV housing the inverter and the battery, then just send line voltage over the distance?

    Tony
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: solar array over 200 feet from inverter

    why is it that if not on the roof that sun access is that far away?
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