Running an Air Conditioner From The Sun - The Holy Grail

Discussion in 'Boat Design' started by CatBuilder, Mar 6, 2012.

  1. CatBuilder

    CatBuilder Previous Member

    Using aluminum rails. Dead simple.
     
  2. michael pierzga
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    Location: spain

    michael pierzga Senior Member

    I mean how do you locate the panels on the boat and orient for best efficiency ?
    The newest ocean racers are using flat face , 45 degree angle ,sheer clamps and mounting the panels on this hull deck surface .

    The boat pictured has them....1.5kw i believe . perhaps 35 ft of 8 inch deep panels per side. You can see the flat sheer clamp
     

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  3. CatBuilder

    CatBuilder Previous Member

    Something like this, Michael. I am not finding the right size catamaran or deckhouse roof, but something like this, with 14+ panels:

    [​IMG]
     
  4. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    Oh. Makes sense. Didnt realize that your cabin top was so big.

    How many watts does a setup like the one pictured generate ?
     
  5. CatBuilder

    CatBuilder Previous Member

    Cabin top is approximately 7 meters x 7 meters. I don't know what the pictured panels above put out because different panels put out different amounts of power. I'd have to know what model of panel they used.

    I plan to generate 3kva/kw, but it is only generated for 5 hours per day, in full sunshine, as an assumption. In the real world, I will have to drop a couple more panels to ensure an average 3kw or so output.
     
  6. Village_Idiot
    Joined: Oct 2007
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    Village_Idiot Senior Member

    No, I am not aware of any off-the-shelf stuff for marine seawater heating/cooling. I just thought it might be an idea worth investigating further.

    I investigated geothermal for my house last year, but my property was not conducive to an easy install. I ended up with a 17 SEER heat pump that had enough rebates to make it an economical alternative, given installation costs, renovation, etc. I have a separate mini-split on the master bedroom that is 25 SEER, I believe.

    As an aside, I would love to invest in solar power here, but the chance of getting baseball-sized hail before the break-even point is reached is far too great.
     
  7. hoytedow
    Joined: Sep 2009
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    hoytedow Carbon Based Life Form

    Hail can be a serious problem in Central Florida when it happens but it is not very frequent that it is large enough to cause significant damage.

    "So, why does Florida have so many thunderstorms, but not that many instances of hail? The freezing level in a Florida thunderstorm is so high; hail often melts before it reaches the ground. Even though hail is not common to the state, there have been about a dozen events of hail of over 3 inches being reported in Florida.

    One event in 1996 in Lake Wales, hail as big as softballs was reported. Damage to the area was done to windows, roves and cars totaling $24 million. In 2007, the area of Kendrick (North of Ocala) reported hailstones ranging in size from 2 to 4 inches.
    "

    At sea in tropical waters there is even less chance.

    http://coaps.fsu.edu/climate_center/thunderstorms.shtml

    http://coaps.fsu.edu/climate_center/images/tstrm_climo.jpg

    [​IMG]
     
  8. mydauphin
    Joined: Apr 2007
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    Location: Florida

    mydauphin Senior Member

    Those put out about 200 watts each, so 14 of them would produce 2.8kw on a bright sunny day at noon.

    By the way these panels are heavy 40lbs, about 600lb overhead. This guy here http://www.sunelec.com/, a friend has them for $200 a piece.

    So for $2800 plus controller of $600 you can do this. Get the best controller you can. Makes no sense to spend your money on all this panels and lose 10% to a cheaper controller to save $100.

    Talk to Charles Kinball there he can help you with low power refrigeration/appliances also.
     
  9. mydauphin
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    Location: Florida

    mydauphin Senior Member

    Oh, I have 2 of these panels, and I paid $800 each about 4 years ago. At least they are getting cheaper.
     
  10. CatBuilder

    CatBuilder Previous Member

    Whoa!! They have 200's for $1 per watt there! Wow! Good link MyDauphin. That is an exceptionally good price. Wow.

    Yes, the 40lbs panels are heavy. I do need to find some lighter ones. That's a lot of shopping and comparing to do, but that is part of the systems task. I will look for the lightest weight ones I can find.

    MPPT charge controllers would be the only way to go. I will have to get programmable MPPTs though, since the LiFePO4 batteries have a different set of voltages from regular lead-acids.

    Good link. Thanks.
     
  11. mydauphin
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    mydauphin Senior Member

    The large panels like this are the way to go, cheap better watt, strong, and will last many years. Don't buy cheapy panels they will crack on you, hail is a real danger at some point or fail because of vibration. I know what I am talking about, I have doing this for many years. These panels require very good MPPT controllers because you set then up at higher voltage so they don't overheat. Overheat cause the power levels to drop at high noon. You also need to lave a couple of inches under to allow for air circulation. Therefore you need the stiff glass panel in a strong frame. My panels are at 80-90 volts at noon and everything runs hot.
    I am looking to upgrade my controller to Outback unit.
     
  12. Brian@BNE
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    Location: Brisbane, Australia

    Brian@BNE Senior Member

    That stiff glass is where most of the weight is. I've wondered about supporting the panels on a 'scantling of pipework' where water is pumped through the pipes. Get your hot water that way, keep the base of the panels cool at the same time.
     
  13. CatBuilder

    CatBuilder Previous Member

    Check. I agree completely.

    I have heard good things about the Outback MPPT controllers. I had Blue Sky on my last boat.

    I will make sure to get panels with 20 year warranties, from a company that will be around in 20 years, even if it means I have to pay more.

    Again, I am a guy who likes to pay a lot for things up front so I don't have to pay later. Ha ha ha. Thanks for that link though.
     
  14. mydauphin
    Joined: Apr 2007
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    Location: Florida

    mydauphin Senior Member

    I pipe my water under panels to cool panel and prewater, before going to solar panel for water. Stiff glass is important, cell themselves are very fragile. Otherwise the panels and connection break a lot. I am using BP panels myself, I got them after they were blown away by a hurricane. So they are very strong. Good panels seldom fail, except by being hit by a sledge hammer force. Also good panel give you more power on partial light, that is very important. Some of the cheaper new panel don't
     

  15. philSweet
    Joined: May 2008
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    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    I went through the preceding in a kinda quick, sorry If I'm duplicating anyone.

    If I was going to set up solar powered AC, I'd avoid using one large single speed compressor. The worst possible scenario is a big 36000 Btu machine cutting in and out with a 10% duty cycle. Humidity comes aboard too quickly and you will be uncomfortable as the humidity zigzags even if the thermostat is set up skinny and is located in the perfect spot, which is hard to do on cats.

    I'd use four 10000 Btu units. My preference would be all water cooled with two having an auxiliary air cooled coil for when you are on the hard.(Aux condensers in engine bay, which won't be running when on the hard.) The condenser for a Puron 3 ton has a surface area the size of a single bed if its high efficiency. It would need about a 24" fan and maybe 3/4 hp fan motor. Where are you putting that stuff? Water cooled is small. What is a squrefoot of real estate worth on your boat, 4-500 bucks?

    The idea is you bring these online sequentially so that there isn't any major load spiking. The solar won't go through the batteries that way. Batteries are a PITA, keep the demand fed direct as much as possible. This also solves the problem of the humidity jumping around. It also gives you load management options such as prioritizing the demand and only allowing three zones to run at any one time, etc. You can save weight this way because the battery bank needs only to be half as big and the inverter can be scaled down a bit as well. The last fifty foot cat I was on had 9 identical units. Three for galley equipment and six for comfort air.

    Somebody mentioned propane fired vapor cycle coolers. Won't work on a boat. They have to be perfectly level and still to work efficiently. They have about a 1/4 mile of tubing laid in at maybe 3 degrees from horizontal and that traps a bubble of light gas in the top as the heavy gas is pumped around. If you mix up the gases or tip the condenser it quits. But they do run continuously, which is very nice. The RV units are quite stout, but not very efficient.

    The "rest of system" cost for 24 volt PV is running about a dollar a (rated)watt.

    MPPTs are way over hyped. I think you could go either way in your case. I would probable not use them but would wire, say 12 panels to three or four cheap controllers and carry a spare. Having said that, you may need to make some allowance for the fact that you are talking LiFeP04. There may not be a cheap option.

    Wiring a house type AC compressor to a boat is really going to put the hurt on the boat wires. Look at the LRA and breaker rating for a three ton. You have to wire for that.
     
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