Building Small Solar System for Pop up - need input

Discussion in 'Power - Site Power/Batteries/Generators/Solar' started by justins, Jan 8, 2017.

  1. justins

    justins New Member

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    Hello,

    I am building a small solar system for my popup:

    - two 100W panels
    - two trojan 6v t105s in series.
    - IOTA 30A charge converter for shore power/charging and maintenance
    - will be used for led lighting, fans, USB charging and occasional 300W "Car" inverter.
    - Everything will be mounting in a ventilated box on the tongue so it can be easily moved to a cabin or a new trailer should we upgrade at some point. Also the batts are Flooded so not suitable for indoor use.

    I am attaching a draft of my wiring diagram based on many systems that I have reviewed. I am hoping that someone knowledgeable in 12V systems might be able to take a peek and let me know if there are any issues with the build and if there is anything I might want to look out for.

    I look forward to any input you might have.

    Best,

    _ justin
     

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  2. lucky13don

    lucky13don Active Member

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    i cant comment on your design. but it sounds like something i would like to do for my pup. I'll be keeping a eye on this. how much weight are we talking for box with batteries,etc?too heavy and its going to be a issue.
     
  3. tombiasi

    tombiasi Well-Known Member

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    Doesn't your controller need a negative battery connection? You realize the meter is only measuring current from the batteries?
     
  4. HiFiDave

    HiFiDave Singin round the campfire

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    You will like having the dual battery, solar option. Many have done it here and it works great! We run all kinds of power at night from ours, even through the power hungry inverter. Next day, zap the batteries back up with Mr. Sun and we are good to go.

    Ya may want to shop around on the batteries there boss. Hey, T105 good battery sure but also a top heavy, high marketing budget company that puts such burden on your back. There are equal to slightly better amp hour batteries out there at a softer price point. I saved a buck and bested amp hours.

    Show us the finished product! [A]
     
  5. justins

    justins New Member

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    Ahh yes. Made a couple of revisions to add the negative power lead to the meter controller and also connected the solar controller negative (forgot to do this in the previous revision).

    The meter docs specify adding the shunt/meter controller right after the negative lead of the battery bank. My understanding is that it will measure surplus current from the the chargers as current flowing back to the batteries. Is this not so.

    Added a couple revisions to this design.

    Lucky13, the whole thing will add about 160lbs. The box will be right up against the trailer box. I think it will add negligible weight to the ball. Might make it a bit more difficult to wheel into the garage by hand ;-).

    Thanks for your questions and input.
     

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  6. rabird

    rabird Howdy!

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    don't see a need for the 2 switches (contoller to batt / converter to batt) there is already a batt switch.

    Having a switch on the panel side of the controller is must for me but the proStar has a switch built in.
     
  7. tdiller

    tdiller Active Member

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    Your switch for selecting solar or electric should ensure that only one or the other can be on at any time. a multipole switch with one normally closed and one normally open should work.
     
  8. justins

    justins New Member

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    Thanks for all the great input. tdmiller, good feedback, I revised with a panel-side switch to the charge controller and, a bi-pole switch to select shore or solar power.

    Bupkis, my understanding is that you don't want to run your batteries into the shore charge-converter when it is not plugged in as there is a chance that the charge-converter will eat a bit of current - hence the switch.

    Would anybody have any input on the wire sizes? Would 6 or 8 gauge be overkill? I want to lose as little DC as possible running to the the trailer.

    Thanks,

    - Justin
     

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  9. unclemark

    unclemark Overland Park, KS

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    A few thoughts:
    -- Nice diagram. You're thinking this through carefully, it seems. Not that I can endorse anything because I'm not an electrician, but I like your approach, and you've got a good grasp on some essential information.
    -- Don't enclose your batteries with your components. Hydrogen gas from the batteries will corrode metals in your charge controller, your meter, your inverter, and your converter.
    -- I have a single 200W panel, and it recharges my Group 31 battery so fast that I usually miss the action.
    -- Weight is always worth thinking about. I love my solar hobby, but it provides a tiny fraction of the power I use camping. I wouldn't be able to persuade myself to do this again unless somebody in my popup needs a c-pap machine someday. Your uses will be minimal too.
    Have you seen this setup? He's a strong believer in fat wire to preserve amps. I used 6ga from the battery myself.
    http://www.popupportal.com/index.php?topic=89253.0
     
  10. rabird

    rabird Howdy!

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    There is no issue having solar and converting charging at the same time or the solar charging while there is no shore power. Or shore power on in the dark!
    Complicate it at will.

    One thing to consider for storage is to cut off battery power to the PU's parasite drains (CO/propane detector, etc) leaving the solar to maintain the batteries. There is no need to shallow cycle batteries daily needlessly.

    There can be an issue with connection/disconnection order of panels/controller/batt.
    Generally the batt is connected first so the controller comes to life and then the panels are connected, disconnect order is to disconnect the panels then the batt.

    Not sure if the pro Star is susceptible to connection order but I note it does have an panel off button.


    WARNING: Risk of Damage
    ONLY disconnect the battery from the ProStar
    AFTER the solar input has been disconnected.
    Damage to the controller may result if the battery is
    removed while the ProStar is charging.
    • To prevent damage, power-down must be done in
    the reverse order as power-up.

    wire should be sized on load and distance.

    I have an issue with cutting off the controller from the batt with a switch. I see no need but I do see how one can cut off batt power prior to disconnecting the panels! See warning above. If the batt needs to be removed, the panels get cut off and then the wires get disconnected.

    Based on that I don't like your main disconnect from the batteries, it should be farther down the line so battery power is cutoff from the PU and not the controller. IMO the controller should be on 24/7. Maybe it the warning above or that my controller has date/time and I hate to reset all the time.

    same with electric brakes, keep on the batt side of any cutoff so they are always connected!
     
  11. CO Hiker

    CO Hiker Active Member

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    Just throwing this out there for consideration; your panels are going to produce electricity even if you put cardboard over them. It will be lower voltage than full on sunlight but if you need to remove the panels for any reason, the wires will be live all the way to the controller. I used a marine grade, dual battery switch between the panels and the rest of the camper. Panel - Anderson connector - switch - fuse - controller. Granted I'm running two Grape Solar 50watt panels in parallel on 10g cable to charge the battery and a pair of USB connectors on the charge controller so our needs are different.
     

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  12. speckhunter80

    speckhunter80 Well-Known Member

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    Overkill for the limited power usage you say you will have, but hey in the immortal words of Tim the Toolman...MORE POWER AARRR..AARRR..AARRR
     
    Maycat likes this.
  13. tenttrailer

    tenttrailer Art & Joyce - Columbus, O

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    + 2 way too much.

    We get by just fine in not so sunny Ohio, with one G31 battery and a 80 Watt panel. That's running the furnace at night.

    I would think about starting small maybe 100W. Maybe go with one 12v g31 battery and add as needed? Just get a controler large enough for 2 panels.

    We liked the portable panels because most of the time the camper is in the shade.

    I do think the next time I replace my battery. I'm going with a g31 100 AH AGM battery for more efficient charge, faster charge and to be able to discharge to 20-30%. My g31 battery would have usable 70 to 80 amps vs 55, it would charge as fast as I could supply the amps vs 24 hours, it would charge at 85-90% efficiency vs 60 to 85 depending where it is in the cycle.
     
  14. justins

    justins New Member

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    Ahaha. speckhunter and tenttrailer Re: Sizing. I think the logic here is that we would also like to be able to sustain some drive-by-day/camp-by-night days to get from here to there, it would be nice to have the reserve in the tank. In addition, Canadian sun is a bunch lower late in the season and I will not be tilting the panels.

    Perhaps, though, I should start with one panel and see how it goes in terms of recharging. In terms of the batteries, I would rather start with a bank that is a bit large than to have to upgrade later.

    I've simplified the design a bit here:

    - one battery switch as opposed to battery + separate switches for the controllers (thanks bupkis, simple=good)
    - added a switch before distribution in the trailer to cut of any parasitic loads during downtime.
    - Added 10Amps to the main and panel fuses to accommodate peaks in the panels and give the trailer demands a bit more room. I will be using 6 or 8ga wire less than 10 feet for the trailer.

    I know that bupkis suggested moving the disconnect after the solar controller, but I would prefer to be able to cut power to everything (no clock or anything on the controller to maintain) - I can get the order right and label everything up well. In any case, I will be removing the flexible panels when in transit and storage.

    CO Hiker, yes. I have a disconnect panel side and will be using a battery switch there.

    Here's the new drawing. Thanks, everyone, for your input.
     

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  15. tenttrailer

    tenttrailer Art & Joyce - Columbus, O

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    If you are doing the drive by day, camp at night. Your battery will be charged up to voltage controlled by the TV voltage regulator. About 12.6/7 V unless you have an AGM battery in the TV from the factory. You should have a battery charge line setup on the 7 pin connector.

    When I do the drive by day campy at night. I don't bring my solar panels. i need my panels if camping 2+ nights with the furnace running.
     
  16. justins

    justins New Member

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    Thanks. I did read about this, the trailer is currently 4pin, but I will be rewiring for 7pin in the future and will keep it in mind. I had the thought that rather than fussing with diodes and grounding issues etc, that it would be easier for me to keep the systems separate?
     
  17. SteveP

    SteveP Well-Known Member

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    You're still making it too hard. I'm sure your ProStar controller has an anti-reverse flow diode installed, my little SunSaver does, read the specs to make sure. Ground the controller directly to the battery and the pup through the frame to the battery as it is now, 2 ring connectors on one stud. Fuse the positive from the controller to the battery. Put a disconnect switch between the controller and the panel.

    The pup's converter is offline until you plug in shore power. When it is online the solar controller will compensate for the charge from the converter so that you don't overcharge. When you have too much 12v load in the pup so that the converter is not providing enough charge the controller will kick in to maintain your battery.

    If you don't have a charge line from your tv the (properly mounted) solar panels can maintain your battery during travel.

    KISS (Keep It Simple Stupid) I always found that to be good advice to myself.
     
  18. justins

    justins New Member

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    Steve, This hurts my brain a bit. The 4pin TV system is grounded to the frame. Will this not cause any issues with the solar system?

    One thing that I did not mention is that I may to remove the tongue mounted power center (mounted in an aluminum truck tool box) from the Popup and use it somewhere else - IE hunting lodge in the fall.
     
  19. tenttrailer

    tenttrailer Art & Joyce - Columbus, O

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    You ground you solar charge controller to the Neg terminal of the battery to get the best connection. But every camper I have seen, the negative (ground) circuit of the 12V system somewhere is connected to the frame. In some cases the frame is the major part of the ground circuit and in some cases it is a redundant ground.

    So yes you can pick up you box and operate it on a battery somewhere other then the camper. But once you connect your battery leads from the camper to the battery trailer frame is in the circuit.
     
  20. SteveP

    SteveP Well-Known Member

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    I am not an electrical engineer but I've been messing with 12 volt systems since the 60's. The 4 pin is isolated from the pup circuits other than using the frame for ground. The current doesn't care what it's using for a ground conductor but will flow, or an equivalent current will flow, back to it's source. The seven pin charge line works on that principle. If current is flowing from the tv it has to flow back to the tv. Same principle with the converter and the solar controller.

    If you look behind the cover of your home breaker panel you will see that even though each circuit is tied to a separate breaker all the neutral, white, wires are tied into a common buss and all of the ground, bare, wires are tied into a separate, common buss, even though individual circuits are out of phase with each other. DC circuits don't have phases and don't need neutral wires but can still share a common ground.

    Having multiple systems through a common ground will not cause ground issues but ground issues can affect all systems, which is why the solar system is grounded directly to the battery.

    The thing is the solar system, converter, and tv can all work together to maintain your battery because the solar controller will only feed current to the battery when the sun is shining and the battery voltage level indicates that charge is needed.

    BTW, I'm sure the ProStar has a provision for an optional battery sense wire, be sure you use it to give the controller the optimum view of the battery charge level.
     

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