Cable from array to controller question????

boywonderboywonder Registered Users Posts: 16
I'm a GREEN NEWBIE and just had a solar system built for my 5th Wheel Trailer. I opted not to install the panels on the roof but keep them portable to move around for the best sun saturation. My problem is, I only had a 30' cable made up from the junction box to the controller. I lose some length inside the front basement where everything is located and doesn't leave much for moving the panels around.

This is the description on the cable:
Nexans-C Ultrex-VN 600v TC THHN/THWN 2XC-10AWG Sun Res Dir Bur (UL) E-64956 02Mar2010 017558

My questions are: Can I extend the length to 40' to 50' without effecting the charging? If so, Would it be better if it was one solid length or can it be spliced to lengthen it?

Any and all help appreciated!!!! There will be more questions later I'm sure.
boywonder

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Cable from array to controller question????

    Welcome to the forum.

    Before anyone can answer that question you're going to have to answer a couple. :D
    Mainly, what are the panels and how are they wired?
    The amount of power you can push through the wire depends on (in this case) four things: the Voltage, the current, the length of the wire, and the size of the wire. So far we know one of those: it's 10 AWG. Without the other three things it's impossible to determine what kind of Voltage drop you've got now and how much it would increase by lengthening the wire.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Cable from array to controller question????

    some questions for you first.

    by 30ft cable do you mean 30ft for the + side and 30ft for the - side just to be sure?
    what are the specs of the pvs you are using, how many, and in what configuration?
    what controller do you have and its specs? are these cables for an mc type connection?

    you beat me to it coot.:p:p
  • boywonderboywonder Registered Users Posts: 16
    Re: Cable from array to controller question????

    Thanks for the quick replies. As I said, I'm very green at this and not familiar with all the terminology yet. It is a double (two wires (+ & -) in one) cable. If you need more specifics than below, let me know and I will try to figure it out. I also have a Onan Propane 5500 generator to back it up.

    Here is a list of the items I had installed:

    2 - Trina 180watt solar modules

    1 - Magnum ME 2012 inverter/charger

    1 - Magnum RC25 controller

    1 - TriStar 45 MPPT colar controller

    1 - Tristar remote meter

    1 - Midnite Mini-DC disconnect panel

    1 - 30' Panel output cable Described in original post.

    1 - Custom Array combiner/j-box

    1 - Ouput cable quick connect plug

    2 - DC breakers

    1 - Lightning Protection

    1 - set 4/0 battery cables/interconnects

    4 - Trojan T-105 250ah Golf Cart Battery

    Thanks again in advance and appreciate all the help.
    boywonder
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Cable from array to controller question????

    Okay, now we're getting somewhere! :D

    30' for both conductors (sorry, but that's one of the confusing bits in calculating V-drop) of 10 AWG
    Your Trina panels are 24 Volt nominal, with a 36.8 Vmp and 4.9 Imp, and you have two.

    Now here's the tricky part: how are those panels connected together?
    One: parallel connection, (+) to (+) and (-) to (-)
    Two: serial connection, (+) to (-) between panels with the (+) from one and (-) from the other feeding the line to the charge controller.

    It's good that you have the Tristar because it will take up to 150 Volts input.
    If these panels are in parallel you're looking at about 2.5% wire drop. Increasing the length to 50 feet will bring that to over 4% which is higher than you'd want to see.
    If these panels are in series you're looking at less than 1% Voltage drop as is. Increasing the length to 50 feet will bring that to just over 1%.

    It is clearly possible to increase the length of this wire without too much loss providing the panels are connected in series.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Cable from array to controller question????

    Just to mention, your 360 Watts of panel is a tad light for 450 Amp hours @ 12 Volts. But since this is an RV application there's other charge sources and the panels are more for extending run time, right?
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Cable from array to controller question????

    seeing you have a combiner j box i am assuming these pvs are paralleled. as it is with a 30ft run your v drop percentage is 3.12%. most try for under 3% and some even try for under 2% and you are a tad over 3% so any additional wire will make this worse. to give you an idea of the % at 40ft and 50ft are 4.16% and 5.2% respectively and i would imagine you did not include the wire lengths from the pvs to the combiner which would also add more v drop.

    i did try to look up the wire, but i am going to make another assumption that this is just straight copper wire you bought to attach to the original wire with the tyco connector. if it were me i'd go with replacing your #10 with at least #8 or even #6 if you go for a 50ft or 60ft run.

    now some may suggest putting the pvs in series and i assume again that you opted not too because of the variable placements you are putting them at, but in many ways it wouldn't matter if you put them in series as they need to be near one another anyway to be combined for the paralleled wiring homerun. the higher doubled voltage and half the current a series connection makes will still yield the same amount of power as parallel, but with less wiring losses. that arrangement will allow you to still use #10 copper wire and see a v drop % of under 2% for a 150ft run length!!! if a pv gets partially shaded the bypass diodes in the pvs will allow that section to be bypassed and you will still get allot of power through. if a whole pv is shaded the v drop of the bypass diodes in that shaded pv will be present and subtract from the pv that is still fully exposed. shading will lower the net voltage over the wires and make the v drop % worse so try to keep them both illuminated. for the record, a series connection at 60ft would show a v drop of .78% and i'm figuring your 50ft homerun of #10 plus any misc interconnections for the pvs.

    no matter what way you slice it the shading of the pvs will be a problem for your power, but the series connection solves your length dilemma best i believe.

    btw, i see you have asked this on another forum as well and i did not see an answer.
  • boywonderboywonder Registered Users Posts: 16
    Re: Cable from array to controller question????

    Cariboocoot & Neil,
    First, thank you very much for your quick replies and your wealth of information. It's really nice to submit a question and get help immediately.

    Since my project is for an RV and me wanting portability, the installer put + & - connectors between the panels and the combiner box. I'm not sure exactly what he did inside the box. It appears that it is both +'s together and both -'s together with one cable coming out with two wires that is one + and
    one -.

    I'm including photos of the panels and box. Don't laugh at my current panel frame (we're sitting in Yellowstone Nat. Park) and we have to use whatever is available. I've drawn up some plans for a portable mounting system but I have to wait until we get back to civilization (Home Depot or Lowes) to build it.

    Since this is still a new system, I'm considering adding two more T-105's. When dry camping we want to have access to the Internet & TV (32"color) and occasional use of the microwave. I have a roof mounted satellite for both Internet & TV and its 110v. I use the generator to deploy and stow the satellite but the router, modem, and receiver are 110v that have to be on while connected. What would adding two more batteries do to my current setup???

    https://picasaweb.google.com/lh/photo/ithsw_V5mwfvjWiVHhHwOg?feat=directlink

    https://picasaweb.google.com/lh/photo/nSnIUctKsUSEfHGrl44rJg?feat=directlink

    https://picasaweb.google.com/lh/photo/__pO8VOMqsEIrEAYw2gOKw?feat=directlink

    OK, it appears my images are not coming through. Is there some setting I need to make to make them visible??? I've changed them to direct link in Picasa.

    Thanks again,
    boywonder
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Cable from array to controller question????

    Well I can fix the link embedding but it says the page isn't there (on all three). Can't do anything about that. Normally you can just attach a picture under "Additional Options", "Attach Files", "Manage Attachments" button (just below the posting frame). This should work with pictures on your computer or at another location (URL).

    Adding more batteries will increase the deficit charging situation and you'll have to run the generator even more to make up the difference.

    BTW, with the 32" LCD (I assume) TV you can alter screen settings and reduce its power consumption considerably. I toned mine down and dropped 100 Watts.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Cable from array to controller question????

    ok, let's back up here, just to be sure, by your telling me if each pv has its own set of wires running back to the rv or not? in fact, why don't you get a hold of the guy and ask him if he put the pvs in series or parallel? if they are in series you can add more #10 wire to extend the distance. if you are not good with wires or can't see how these pvs are wired up then it may be a good idea to let someone who is familiar do the wiring.
  • boywonderboywonder Registered Users Posts: 16
    Re: Cable from array to controller question????

    Thanks again,
    Yes, on the TV, when we're on the inverter, I run the power option down and dims the picture, when on generator, I run the power option up and brighten the picture.

    By increasing from 4 to 6 batteries, wouldn't that extend my inverter time as long as the batteries are charged up good? I'm currently getting as much out of the panels (Sun) as I can get each day, then run the generator to float the batteries as needed.

    Also, If I changed the wiring from parallel to series inside the combiner box, is there any changes that would have to be made from between there and the rest of the setup as far as wiring, adjustments, settings, etc.??

    Can you point me to a good source for learning more about solar? Example: on the Tri-Star monitor I see all these numbers with v's, a's, ah's, kwh's and so on and I don't have a clue what I'm looking at. Ha ha. I went to the MorningStar website and picked up a little help but would really like to learn more.

    I will keep trying to send the photos.

    Thanks again,
    boywonder
  • boywonderboywonder Registered Users Posts: 16
    Re: Cable from array to controller question????

    Trying again with images (3) as attachments.

    boywonder
  • BB.BB. Super Moderators, Administrators Posts: 32,015 admin
    Re: Cable from array to controller question????

    There is the Image button (yellow sky, mountain range) which will insert a link to your pictures.

    There is also the "paper clip" which will allow you to upload (not huge) pictures/documents to be hosted by the forum directly.

    Here is a thread/FAQ with a whole bunch of information (including links to books/websites).

    Working Thread for Solar Beginner Post/FAQ

    See what strikes your fancy there.

    -Bill
    attachment.php?attachmentid=2100&stc=1&thumb=1&d=1317060345
    Attachments worked fine. Here is an example of direct link (to the forum):
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Cable from array to controller question????

    The view of the junction box definitely shows the two panels are wired in parallel. Pretty good seal on the connections too, I'd say. It will take a bit of effort and care to change that to serial connection. The Tritar MPPT controller will not care which arrangement is used for input: it can take up to 150 VDC in.

    Going from four to six batteries will increase the run time of the inverter. But you definitely won't be able to charge from solar alone. For 225 Amp hours @ 12 Volts you'd "ideally" have around 400 Watts of panel. Double the battery capacity, double the panel to recharge it. Triple the battery capacity, triple the panels. Without the extra panel you will need to rely on the generator to make sure the batteries are kept up. I'm not too keen on more than two parallel connections on battery banks either, but it can be done. Just keep an eye on them. BTW, you should run the generator to do the Bulk charging (first stage) and let the panels take over to complete the charge when the current demands go low enough. They could handle much of the Float too, until the sun goes down or demands go up. Running a gen for Float is a lot of fuel for a little power.

    As for a really good source for learning about solar, in all honesty I think you're there (here). It may take hours of reading and asking, but there's a lot of smart folk around here who are in the industry and/or have used solar for years. It's not a simple subject so it does take a while to get a handle on it.
  • boywonderboywonder Registered Users Posts: 16
    Re: Cable from array to controller question????

    Thanks B.B. for the links and info on images. I'll be doing lots of reading, no doubt.
    Thanks Cariboocoot, very good point on Bulking w/generator and Floating w/panels. I feel like I'm in the right place on this Forum for learning. The other Forum I submitted too at same time, I've yet to get a reply. I'll be reading as much on these posts, f.a.q.'s, and doing searches so I won't sound so "newbie" from now on!!!
    Thanks guys,
    boywonder
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