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Thread: anyone here using solar panels to charge?

  1. #1
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    Mar 2006
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    Philadelphia, PA
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    Default anyone here using solar panels to charge?

    been thinking about setting up the small solar panels to charge battery for camping. would like some input as to what kind and how they work. i camp all year, every type of weather, curiuos if they would be worth installing or if they would only work on those picture perfect days i read about in magazines?

  2. #2
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    Feb 2006
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    Prescott, AZ
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    We do a fair number of panel set ups for our trailers. When it comes to the output of panels we only count on 70% performance because rated outputs are based upon full sun and accurate placement of the panel towards the sun. It is good to know how to apply Ohms' law to your power requirements to evaluate your needs: Amps x Volts = Watts
    Lets say you decide to hook up a 20 watt panel to your battery bank and you live in AZ where you can count on an average 6 hours of full sun daily. Here's what you could reasonably expect on the low end:

    ((20watts x .70 efficiency)/12 volts)) x 6hrs= 7 amps.

    On the high end;

    20w /12v x 6hrs = 10 amps

    Remember that your battery is essentially a fuel tank that has a maximum capacity rated in Amps. Hooking up a solar panel to a fully charged battery without a charge controller could cause overcharging of the battery that will shorten it's life.

    A very good book has been written on RV electrical systems and covers solar panels. It is written in lay person's terms and is an easy read. I got mine from Amazon.

    RV Electrical Systems by Bill & Jan Moeller

    Good luck amigo!
    Mario Donovan, Trailer & Vehicle Builder and Traveller.
    12' JK Rubicon w/ Habitat, self contained, 48K miles & counting
    92' Jeep MJ, 371K+ miles of dust & joy, retired
    "No matter where you go, there you are"

    www.adventuretrailers.com
    ATOverland

  3. #3
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    Sep 2005
    Location
    Snake River Plain,ID
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    We have a Kyocera 120 and a K60 (space limitations) on the roof of our ATRV with a RV Power Products Model 2000E Charger Controller/Booster. During our entire trip to the Arctic Circle last August/Sep I never had to use the genset to re-charge the five (yes, [I]five[I]) deep-cycle batteries on the trailer.

    This is overkill, but I like to err on the positive side. When we set up our solar system on the house in Baja six years ago we determined what our 'needs' would be, figured out the number of pv panels/batteries and doubled it.

    Mario gives excellent advice above. I have that book he mentions and I do recommend reviewing or purchasing a copy.

    If you're wanting to only maintain your vehicle battery over several (many?) days of non-engine charging, a small pv panel/charge controller is all that's required. If, however, you have a 12v fridge, a blender for you margueritas, a couple of exterior 12v lights (flourescent or LED of course) for the campsite, then you'll have to increase your pv wattage. That book is an excellent guide.
    "I'm ahead of the game and can afford to take chances." --Theodore Roosevelt
    '11 Mini Cooper Clubman, '04 Dodge Dakota 4X4

  4. #4
    Join Date
    Jun 2005
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    Tucson, more or less.
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    Good advice above, all of it.

    If you expect to maintain a charge for long stationary periods while running an Engel or other significant loads, you'll need to look into 100 watts-plus of real PV capacity, and, as noted, a simple charge controller, since uncontrolled charging of Optima-type batteries is not good. If you just want a small system to extend your time between running the engine, you can get away without it, as Scott does now with his dual flexible panels.

    The many hours of sunshine in Arizona are great, but also keep in mind that panel output goes up significantly in cold weather. Cold and sunny is best.

  5. #5
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    Jun 2005
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    On a related note, we had some discussion on how to figure out your power requirements in this thread, which may be useful in trying to determine how much solar you want to go for.

  6. #6
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    Mar 2006
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    Philadelphia, PA
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    thanks for the input, i do understand ohms law, but will keep an eye out for the book. also my intentions are, i have a trailer i use with a single battery for now. but what i would like to do would be install 2 with some sort of charging system, i have seen the solar set ups at boating supply shops. i now just charge up a few minutes by hooking back up to truck for a while each night, but that is sometimes easier said than done. thinking that by using a solar charger i could simply set up and possibly not worry about it.

  7. #7
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    Feb 2006
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    Here's a look at the dual set up in the nose box my own trailer if you need some ideas. The little black box on the right hand side is a Shell RV-20 charge controller, the inverter is a Xantrex 1500 and the batteries are Lifeline AGM group 31 making a total of 210 Amps. The solar panel I use is a Unisolar 64, it plugs into an socket on the exterior of the box.
    Attached Images Attached Images
    Last edited by elcoyote; 04-05-2006 at 09:19 AM.
    Mario Donovan, Trailer & Vehicle Builder and Traveller.
    12' JK Rubicon w/ Habitat, self contained, 48K miles & counting
    92' Jeep MJ, 371K+ miles of dust & joy, retired
    "No matter where you go, there you are"

    www.adventuretrailers.com
    ATOverland

  8. #8
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    Jun 2005
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    Prescott, AZ
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    I have been quite satisfied with the Iowa Thin Film panels I am using, though my mounting configuration showed its limitation in the winds last weekend.

    The system generates 40 watts at 15v under perfect conditions.
    Scott Brady
    Overland Journal
    D1 | LJ78 | LR4 | MKIII | J8 | G-Wagen | Range Rover Classic | TE630

  9. #9
    Since our MO is going deep then stay in one place for an extended amount of time (3 weeks to a month+), PV's are worth their weight in gold!

    Regarding not having PV's...It takes more than an motor idle to charge batterys. In fact self-exciting alternators "kick in" at around 800 to 900 RPM. So if you are just sticking to motor charging, it would be wise to rig up some kind of hand throttle (rock on foot pedal, etc.)


  10. #10
    Join Date
    Jun 2005
    Location
    Pojoaque, NM
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    Quote Originally Posted by expeditionswest
    I have been quite satisfied with the Iowa Thin Film panels I am using, though my mounting configuration showed its limitation in the winds last weekend.

    The system generates 40 watts at 15v under perfect conditions.
    Powerfilm now makes a foldable 60 watt panel. Looks like a great option for someone not able to have a permanent mount. The unit is pricey though, around 1300 for this setup.

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