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Thread: possible starter system

  1. #1
    LHBA Member BoFuller's Avatar
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    possible starter system

    I'm looking at creating a starter system to maintain us for 2-5 years as we proceed on our building project. I want to be able to run everything in the trailer (TV, blender, vacuum, water pump, lights, etc) without having to run the generator all the time. I'm thinking 3 200W solar panels; a Xantrex C40DD charge controller; 4 Trojan T-105 batteries; a Xantrex TR2412 inverter/charger; and maybe a TriMetric battery meter. I'll go for a 12V system and hope to produce around 1.5 to 2.0 Kwh per day.

    I'll use the generator when I want to run the table saw or the A/C.

    What say you experienced/knowledgeable people? Like Rod (hint, hint, hint)

  2. #2
    LHBA Member rreidnauer's Avatar
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    Well, with 600 watts, you should acquire at least 1.5 to 2.0 Kwh per day.

    I was just reading your thread over on wind-sun.com and I'd say they got it covered pretty good.
    With the 600w of panels, you could go up to eight T-105s to provide a safety buffer and provide less wear-n-tear on them. I agree, the 100w bulb is a waste of energy, but gives you a good perception on how 2.4 Kwh a day can be consumed rather easily. I'm worried about that furnace blower motor. You'll have to watch consumption on that. Consider installing an unpowered, direct-vent (NOT ventless) heater if you got some free wall space. I also agree on purchasing an MPPT charge controller. Not only are they far more efficient, they are also very flexible for when you upgrade your system, possibly changing to a higher (more efficient) bank voltage. The TriMetric is a nice little piece to have. (I have one) It will really help you keep a grasp of what the whole system is doing.

    Finally, as mentioned on the other forum, conserving is way easier than producing. Find ways to cut your power usage, like the unpowered heater mentioned above, and LED lighting. Insulating is a big help wherever you can. I've double the average R-value of my trailer by increasing insulation in just the ceiling and floors. (can't do any more for the walls) I still have more to do by skirting the bottom to prevent wind from blowing beneath, using roof vent pillows, heat-shrink film over windows, and sandwiching 1/2 poly-iso between the doors and screen doors, but there is a definite difference in heat/cool energy usage already.
    All my bad forum habits I learned from LHN

    Rod Reidnauer
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  3. #3
    LHBA Member BoFuller's Avatar
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    Thanks Rod. I was debating the skirting. I thought it was a good idea to keep the cold wind out, but my wife thinks it will invite more critters. We already have a little battle going with the local mice population. They were getting in around the slideout, so I went around the border with that expanding foam stuff. That stopped them there, but now they (one or two - not like we are getting overrun) are coming down the furnce vent/chimney and coming through the floor vents. When we don't need heat I duct tape the vents and that has kept them out, but now it's getting into furnace weather. You think skirting will bring more critter problems?
    If I was to increase the panels or the batteries, which would be better? 3 panels and 6 batteries or 4 panels and 4 batteries?

  4. #4
    LHBA Member jrdavis's Avatar
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    you could always get a cat and put its bed and FOOD under there....
    They'll find a way to eliminate the problem.
    Thats why I have 4-5 "farm cats" at all times.
    they are NOT indoor animals.
    Iowa Log Building -- some day
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  5. #5
    LHBA Member rreidnauer's Avatar
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    Wholly mackerel! Those must be some crazy mice. I can't even figure out how coming in the furnace vent could lead them to floor vents. (combustion chamber is completely separate from internal ductwork) Anyhow, don't tape over the vents, just cage over them with metal screening or expanded metal. When insulating under the trailer, I finished things off with 1/2" foil-faced foam insulation board, and taped all joints with foil tape, to make one seamless barrier against critters. So skirting wouldn't be much issue for me. I guess if you sealed up joints, and bury the bottom edge in the ground, you should be pretty secure from those critters. I just missed a pile of free aluminum-clad insulated panels used for building walk-in freezers. Those would have been amazing for skirting.

    As far as panels to batteries, it's a little tricky to determine. It all depends on how much load you'll be putting on the batteries. The safe answer is more batteries over panels, because it keeps your amp.hours lower and state of charge higher, which both extend the life of your batteries.
    All my bad forum habits I learned from LHN

    Rod Reidnauer
    Class of Apr. 9-10, 2005
    Thinking outside the vinyl sided box

  6. #6
    LHBA Member BoFuller's Avatar
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    Rod, I am still going with the 3 235v panels but I cut back to 2 batteries - 16RE, instead of the 105's. I will be a little more conservative on the usage setup for the trailer as I am now planning on having the home done in 2 yrs instead of 5. I could go with just 2 panels, but I got a pretty good deal on them so I got a dozen. I'm thinking that will be plenty for the home and trailer. I figure my larding to setup the system for the trailer will be my education for doing it more accurately for the home.

  7. #7
    Bo,
    We have been doing a similar thing, with a few differences. We have a 48V 220ah battery bank hooked up to our inverter and a 12V 400ah battery bank hooked up directly to the 12v in the RV, and a 1.5kw array. I initially tried to go with a 48V to 12V converter to power the 12v in the RV, and then decided to go with a battery bank on the 12v side to expand our storage. We do have the ability to charge the 12v bank from the 48v bank using a charge controller. Since it has warmed up this has been working great, we have only fired up the generator 3-4 times since March. However, winter was a different story. We basically ran it 3-4 times a week just to keep up with the furnace blower. ANYTHING you can do to insulate will save you a lot. We considered even using straw bales around the rig instead of a skirt (the skirt seemed excessive to us), but couldn't locate them in time. If you think you will need a skirt order it now, if you wait until its cold you'll drag your COLD feet and by the time you decide to buy one winter will be over and you won't need it! Now that we aren't running the furnace we can make it 3-4 days without sun and no generator, which is why we have had so little generator use. If we have more than one sunny day in a row, we are pretty much at float charge by noon every day, and we can pretty much recharge from 50% depth of discharge with a good day of sun. Good luck and enjoy it!

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