Portable Solar Panel Setup

TrvlngnrsTrvlngnrs Registered Users Posts: 5
Hi everyone.

I have a chance to get a new Xantrex C40 controller for $50: http://www.altestore.com/store/Charge-Controllers/Solar-Charge-Controllers/PWM-Type-Solar-Charge-Controllers/Xantrex-Solar-Charge-Controllers-Pwm/Xantrex-C40-40A12-48V-Charge-Controller/p2070/

I'm thinking a getting this 130 watt panel: http://sunelec.com/index.php?main_page=product_info&cPath=5&products_id=645

I'm thinking of hard wiring the controller in my travel trailer, then attaching the solar panel with approx 30' of gauge wire to make it portable. It will just help to decrease run time of my Honda eu2000i generator charging my two Trojan T105 batteries. I live in southern UT, so I get lots of sun, but tend to park the trailer in the shade.

Currently I have a 15watt Battery Minder solar battery conditioner on my trailer to keep the batteries charged while the trailer is in storage. http://www.batteryminders.com/batterycharger/catalog/BatteryMINDer-Solar-Charger-Controller-Desulfator-12-Volt-with--p-16140.html

Is there a problem connecting both systems to the batteries?

Thanks for your advice
Trvlngnrs

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Portable Solar Panel Setup

    The C40 is over-kill, as one 130 Watt panel will never come close to 40 Amps @ 12 Volts. 8 Amps maybe.
    But, $50? What's wrong with it? That is a suspiciously low price for C40 - about 1/3.

    Are you planning on adding more panels in the future? It would certainly allow.

    There's shouldn't be any trouble with the two charging systems hooked together on one battery set, except that while in storage the C40 may drain off some current (won't provide any without sun on the panel of course). Simply disconnect it while the trailer is out of use.

    It's a good plan. Make sure whatever mounting rack you build for the panel is adjustable and sturdy. You don't want it knocked over by wind or some such while you're happy camping! :D
  • TrvlngnrsTrvlngnrs Registered Users Posts: 5
    Re: Portable Solar Panel Setup

    Thanks for the advice!

    There isn't anything wrong with it. it's new in the box. It came with a kit, but the owner ended up upgrading the controller, so he never used it.

    Is there any specific type of wire I should use?

    I saw some 6 gauge flexible welding cable for $1.40/foot. Is this overkill for a 30' run between the panel and the controller?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Portable Solar Panel Setup
    Trvlngnrs wrote: »
    Thanks for the advice!

    There isn't anything wrong with it. it's new in the box. It came with a kit, but the owner ended up upgrading the controller, so he never used it.

    Is there any specific type of wire I should use?

    I saw some 6 gauge flexible welding cable for $1.40/foot. Is this overkill for a 30' run between the panel and the controller?

    The panel is rated for less than 7 Amps output, so you certainly don't need 6 gauge wire. Thirty feet isn't really that far of a run either. A rough guess would be that 14 gauge would probably suffice. Perhaps 12.
    For absolute accuracy in determining the wire size, see the Voltage Drop Calculator:
    http://forum.solar-electric.com/showthread.php?t=29
    (And more thanks to Solar Guppy for taking on hosting this valuable tool).
    (It doesn't run on my net book so I can't do the calc for you.)

    I would recommend a weather-proof cable, such as used for outdoor extension cords. But do not use the standard 120 VAC connectors or sometime somebody is going to do something very wrong and something will go "poof!"
  • BB.BB. Super Moderators, Administrators Posts: 32,800 admin
    Re: Portable Solar Panel Setup

    You can also play with this simple on-line voltage drop calculator. 30 feet (one way) and 7 amps will give:
    • 14 awg => 1.3 volt drop
    • 12 awg => 0.8 volt drop
    • 10 awg => 0.5 volt drop
    • 8 awg => 0.3 volt drop
    • 6 awg => 0.2 volt drop
    A 10 awg cord would be great. A 12 awg OK... 14 will probably work OK in cool weather--but I would go heavier.
    • V wiring-drop = Vmp - (Vbatt+Vcontroller-drop)
    • V wiring-drop = 17.5 volts - (15 volts equalizing + 1 volt controller drop) = 1.5 volt margin
    And remembering that hot panels have Vmp dropping with temperature.

    Regarding plug ends--I like ones that can pull out (instead of twist locks)--people trip or you pull the RV away from the campsite and the panels are still setup (oops).

    Also, secure the panels against wind damage (at least--theft can be another issue).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PhilSPhilS Solar Expert Posts: 370 ✭✭✭
    Re: Portable Solar Panel Setup

    I use a similar setup on my RV. I have a portable panel (~120w IIRC) on 30' of wire because I too like to park in the shade. I also have another panel the same size hard mounted on the roof. (on hindsight I could/should have made the portable on 50' of wire... sometimes 30' is a little short of the best sun)

    Both panels run through a C30 controller (with the optional gauge faceplate so that I can monitor performance). The roof mount uses the factory wires that were terminated under the fridge vent.

    The portable unit I have connected using a trailer wiring kit. The short pigtail attaches to the controller and the plug is inside the door that you open to raise/lower the landing legs. So, open the door, pull out the pigtail, close the door over it (flat wire, plastic door, no problem), connect the wire from the panel.

    This is 4 conductor wire with polarized plugs. I use two wires for each + and each -. The plug on the panel wire is the one with 3 exposed terminals. The pigtail on the RV is the one with only one exposes terminal, and that terminal and the wire next to it are wired to negative so there isn't an exposed terminal on the pigtail that is 12V, to prevent it from contacting any metal on the RV and causing a problem (to say the least).

    I do not have any mount for the solar panel. I only drilled a hole in the frame big enough to pass a good bicycle cable lock through. Since we usually park around trees it's easy enough to find a place to lean the panel in the sun and lock it to a tree. Also easy to move as the sun angle changes. The cable both keeps it from blowing over, and "walking off".

    One time we had no trees and I just put the portable panel up on the roof.

    Phil
  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Portable Solar Panel Setup

    I'd go with a standard 50' contractor's 10 gauge twist-lock extension cord. 3 wires, black, white and green - perfect.

    There is a connector issue though...as Coot mentioned there is a (slim) possibility of a mixing ac and dc accident.

    One thing I don't like about Phil's (sorry Phil) setup is that there are exposed positive and negative pins on the PV panel, which means while it has sun those pins are hot. I think I'd have reversed the connectors so that on the PV panel there would be only one exposed pin so the panel can't be shorted out and the guy handling it can't get bit.

    One way to prevent the accidental ac/dc mix problem would be to switch ends - i.e., have the male at the PV end and the female at the RV end (which would mean the opposite for the cord - female at the PV and male at the RV) - but that creates the same problem as Phil's setup - hot exposed pins coming off the PV.

    I guess what I'd end up doing would be to cut off the female end of the cord and make the cord male at both ends, so that I could use female at the PV (no exposed energized pins) and female at the RV. That would require that the cord always be plugged in to the RV first and then the PV.

    Otherwise, you would be toting around the RV end of the cord with exposed hot pins that are energized by the PV.



    EDIT: Left something out...

    With the cord male at both ends, it also (seemingly) prevents Coot's accident, since the hot end (female) of a normal 120v twist-lock CAN'T be plugged into either the RV or the PV.

    But no...that's no good either, since one male end of the modded cord could be plugged into the PV and the other into 120vac. Or one end into the RV and the other end into 120vac.

    Hrmmm...tricky issue.
  • nsaspooknsaspook Solar Expert Posts: 396 ✭✭✭
    Re: Portable Solar Panel Setup
    dwh wrote: »
    I'd go with a standard 50' contractor's 10 gauge twist-lock extension cord. 3 wires, black, white and green - perfect.

    There is a connector issue though...as Coot mentioned there is a (slim) possibility of a mixing ac and dc accident.

    One thing I don't like about Phil's (sorry Phil) setup is that there are exposed positive and negative pins on the PV panel, which means while it has sun those pins are hot. I think I'd have reversed the connectors so that on the PV panel there would be only one exposed pin so the panel can't be shorted out and the guy handling it can't get bit.

    One way to prevent the accidental ac/dc mix problem would be to switch ends - i.e., have the male at the PV end and the female at the RV end (which would mean the opposite for the cord - female at the PV and male at the RV) - but that creates the same problem as Phil's setup - hot exposed pins coming off the PV.

    I guess what I'd end up doing would be to cut off the female end of the cord and make the cord male at both ends, so that I could use female at the PV (no exposed energized pins) and female at the RV. That would require that the cord always be plugged in to the RV first and then the PV.

    Otherwise, you would be toting around the RV end of the cord with exposed hot pins that are energized by the PV.



    EDIT: Left something out...

    With the cord male at both ends, it also (seemingly) prevents Coot's accident, since the hot end (female) of a normal 120v twist-lock CAN'T be plugged into either the RV or the PV.

    But no...that's no good either, since one male end of the modded cord could be plugged into the PV and the other into 120vac. Or one end into the RV and the other end into 120vac.

    Hrmmm...tricky issue.

    Some of the best connectors for DC cables are Anderson types. http://www.amazon.com/Power-Pole-Connector-Black-Anderson-Sermos/dp/B000QUZD4W/ref=pd_sbs_t_1
  • BB.BB. Super Moderators, Administrators Posts: 32,800 admin
    Re: Portable Solar Panel Setup

    They are OK--Our host NAWS also sells them too:

    Anderson Power Pole Series

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • TrvlngnrsTrvlngnrs Registered Users Posts: 5
    Re: Portable Solar Panel Setup

    You guys are great! Thanks for all the advice you've given me!!

    Is there a particular panel you would recommend for my situation. I'd like a 90 - 130ish watt panel. Not the most expensive, since it will be more vulnerable to theft, etc.

    The Sun 130 watt panel I linked above is $260, but....the company charges $105 for shipping! I'll look thru NWAS to see what they have to offer........
  • BB.BB. Super Moderators, Administrators Posts: 32,800 admin
    Re: Portable Solar Panel Setup

    Check the $$$/watt pricing. Also, look at the physical size of the panel and that you can safely transport a thin pane of glass in an aluminum frame (tempered glass--one good shock and it will shatter).

    Typically, >100 watt panels are less expensive per watt. The Kyocera panels seem to be really nice. NAWS has a 135 watt unit either with MC type connectors or a wiring box on the back (most larger panels are all MC connectors).'

    If you choose the pigtail versions--get a male / female 3' MCx connectorized cable and cut in half--connect the cut ends to your system.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Portable Solar Panel Setup

    DC power cable, I've used "malibu patio light" cable, tough insulation for laying on the ground, and heavy gauge wire for all those 20watt bulbs.
    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 ,

  • KamalaKamala Solar Expert Posts: 452 ✭✭
    DC Connectors

    I have a Marinco trolling motor plug/receptacle purchased for a different project which is currently on the "back burner." I have thought about using it for the PV connection to my camper. The above link only mentions a 12V rating. The package I have indicates 12/24/36. I can't find a current rating, but I think that a the draw of a trolling motor at any of the 3 system voltages would be much greater than the output of a small PV system.

    I also have an Anderson connector that I have not installed. But with this connector I would have a dangling wire instead of a "weatherproof" female connector.

    Ah, but then there is the issue raised by dwh regarding live PV terminals. But neither Marinco connector could be mated to AC, which is good. And there is also BB.'s caution against twist lock, which is a feature of the Marinco.

    What a whorled!
  • CrotalusCrotalus Solar Expert Posts: 26
    Re: Portable Solar Panel Setup

    Here is the Marinco plug and socket in use. I keep the plug on the solar panel wrapped in bubble wrap when not in use so nothing can touch the pins on the plug. I also store the panel in a wood box custom made for the panel when I travel. I put together an extension cord using 10 gauge marine wire. I created the decals using wet slip decal paper printed on my home printer. The wires are attached inside with a terminal block enclosed in a cabinet under the bed. I have room on the terminal block to add more connection in the future. The system works for me!

    I believe that if you drove off with the power cord connected to the panel and your RV with a pull plug your panel would have bought the farm. If the plugs had a good connection then they would be tight.
  • PhilSPhilS Solar Expert Posts: 370 ✭✭✭
    Re: Portable Solar Panel Setup
    dwh wrote: »
    One thing I don't like about Phil's (sorry Phil) setup is that there are exposed positive and negative pins on the PV panel, which means while it has sun those pins are hot. I think I'd have reversed the connectors so that on the PV panel there would be only one exposed pin so the panel can't be shorted out and the guy handling it can't get bit.

    It seemed like it was gonna be a trade-off no matter how I wired the portable panel. I like Crotalus' installation... very clean and professional!

    But for his install and mine:

    How much "bite" potential is there from one panel? On both, you'd have to get a finger across both a pos and a neg or ground terminal. Then what? I doubt you'd even get a 'tingle', let alone a 'shock'. :confused:

    I was more concerned with an exposed terminal tied to the RV battery bank. Then there'd be a potential from blowing a fuse (best case) or arcing and starting a fire (worst case) if that terminal came in contact with the aluminum siding or a screw or a frame part.

    There are some nice connectors available but this was a budget experiment with an extra panel I had, and it's worked so well that I doubt I'll change anything.

    Phil
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Portable Solar Panel Setup

    As PhilS says, a single panel even in full sun won't put out enough to do person any serious harm.
    But it will put out enough to cause arcs and sparks and possibly fire if the energized cord is shorted in some way. The simple solution is to put a fuse at the panel. A standard 10 Amp auto-type fuse should handle one panel's output, and should blow before anything nasty happens.

    There's only so much "idiot-proofing" anyone can do, because the world is always making bigger idiots. :p
  • BB.BB. Super Moderators, Administrators Posts: 32,800 admin
    Re: Portable Solar Panel Setup

    Fuses on a per-panel (or string) basis will only, at best, protect against a reverse polarity connection to the battery bank (or issues if there are more parallel strings in the total array).

    A properly sized fuse will not blow under standard conditions if the one panel (or series string) is shorted. The fuse is typically around 2x Isc rated current.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Portable Solar Panel Setup

    Doh! Maximum current of the panel is the maximum current of the panel! I was not thinking! :blush:

    There's no way to make it 100% safe. Anderson connectors so no one hooks up the wrong thing (and exposed contacts aren't available) combined with taking care to not make/break connections when the panel is in sun seems about all that can be done.

    Over-all, probably not that dangerous.
  • TrvlngnrsTrvlngnrs Registered Users Posts: 5
    Re: Portable Solar Panel Setup

    Good discussion guys.....thanks!

    These Anderson Connectors look pretty idiot proof: http://www.andersonpower.com/products/powermod-hp-connectors.html

    Does a portable panel have to be grounded by using a 3-wire cable?

    Trvlngnrs
    St George, UT
  • BB.BB. Super Moderators, Administrators Posts: 32,800 admin
    Re: Portable Solar Panel Setup

    Not really... I would not bother. Just don't set up if lightning is predicted.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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