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  1. #1

    Energy Efficiency and Solar Power on a 53MY

    It's been a few months since I purchased the boat and moved aboard, and am starting to get my head wrapped around all of the various systems. I've taken her out in Baltimore Harbor a few times for short trips, but mostly I'm using it as a condo. My goal is to eventually use it for more cruising in a few years, but for now I'll be attached to shore power most of the time. I pay $0.25 per KWH for electricity here in the marina, so reducing the amount of shore power I need will both save on the electric bill when I'm "home" and reduce the need to run the generator when I'm out cruising. BTW, my background is in residential energy auditing and building small boats.
    What I've done so far:
    Before I tackle the project of adding solar to the already complex electrical system of the big boat, I decided to start off small. I bought a wonderful little wooden dinghy that has a sail rig and rows like a dream (11' Shellback Dinghy). I mounted a 55 lb. thrust Minn-Kota motor-mount electric motor on the rudder, which is powered by a 50AH lithium battery that is my portable power station. I am charging that with a 100 W solar panel. I put together a nice little ammo box that holds the battery, charge controller, a circuit breaker, volt meter, and has various outlets to connect the motor, USB charging, and 12V accessories. I have a little 300W pure sine wave inverter to connect to it for powering small AC appliances. I can also use the DC power in the battery for charging my phone and my laptop, and for a 12V electric blanket. I haven't mounted the solar panel permanently yet, as I am still trying to figure out where and how to do that and if I need to add another panel. For now, I'm just trying to see how much energy I can create/store/use with this little mini system. (Well, technically energy cannot be created or destroyed, but you know what I mean.)
    What I'm planning on doing:
    I've ordered ten 3.2V 280AH lithium cells to make a 32V battery. I'll be replacing one of my 32V battery banks with those, while using the remaining lead acid bank to provide the 980CCA needed to get the engines started when it's cold out. Basically, I'll use the lithium to handle all of the 32V appliances other than the starters on the engines, because they can be charged and discharged many more times than the lead acid batteries can. I'm converting the water heater (19 gal.) from 240V AC to 32V DC by installing a 36V 1200W element (should work just fine). Once I get all of that installed, I'll keep track of my 32V system usage and size my solar system accordingly. To start off with, I'll use the shore power (or generator when out cruising) for large AC appliances and the solar for keeping the batteries charged and all of the DC needs. Then I'll see about adding a second solar system to handle the AC appliances as well. I like the idea of keeping the two systems separated, rather than one big system. I may even add a smaller third system for 12V.
    As far as efficiency improvements go, I'm using an induction cook top, all EnergyStar appliances, I've replaced all of the incandescent bulbs for LED and wrapped the water heater. The new full-size fridge will be here next week. (I'll let you know how getting the old one out and the new one in goes.)
    I'm also installing a little diesel heater. I'm curious to see how it will compare to using the heat pumps (and electric space heaters) at various temperatures. I may add a second one at a later date. I'd also like to see how hard it will be to remove (then put back) the head liners in the salon, galley, and master state room to install insulation. (Any ideas?)
    That's where I am for now with the efficiency upgrades and solar conversion. I'm anxious to hear people's thoughts on the project and am happy to hear about any ideas you may have.
    Thanks for taking the time to read all of this.
    Thom

  2. #2

    Re: Energy Efficiency and Solar Power on a 53MY

    I hope you're not using standard lithium ion cells. They burn long and hot and are not safe for that type of use. Also they need specific charge characteristics not available with your standard alternators.

    The idea is sound but if your not using the right gear your going to have problems.

    I sell a lot of liFePo batteries for marine use. There's not a 32 volt solution for a reason.
    Scott
    41C117 "Hattatude"
    Port Canaveral Florida.


    Marine Electronics and Electrical Products Distributor.

  3. #3

    Re: Energy Efficiency and Solar Power on a 53MY

    I can't speak to the electrical parts of the project. Scott's concerns, though, are significant. Old-style lithium batteries have a habit of overheating. I'd be real careful about that.

    As far as the diesel heater: you'll find that they put out a lot more heat than your reverse cycle AC does. Your reverse cycle AC isn't much use when the water temp is below about 45 degrees. I lived on a boat in Baltimore Harbor for years and it was pretty cold there in the winter; plenty of snow and ice. And windy.

    The problem with using these boats as houses is basically that they wee not built for it. They aren't insulated, which means a larger demand for heat as they don't hold it in, and they don't have a lot of robust electric supply like a house does. And there are multiple potential points of failure in the electric supply; it isn't hard-wired with a set of weather proof cables coming into the roof like a house is.

    That said, I liked it up there. I was a lot younger and tougher; I used to walk up to the showers barefoot in the middle of winter. I would not do that now. So if you're willing to put up with a few hardships, no pun intended, you should be okay.

    My marina up there, the Anchorage, had a live water hose secured to a piling and lying under the dock. We'd pull it up when the tanks needed to be filled. This eliminated having to move the boat to fill them.

    Don't leave the boat with a lot of loads running. You may come back to a fire.

  4. #4

    Re: Energy Efficiency and Solar Power on a 53MY

    We anchor out quite often and have been using 4 100 watt solar panels that charge our 32 volt bank. For us this is enough power to run our large refer and a smaller beer fridge plus toilets and misc stuff all day with a slight gain. We use the gen set mainly for cooking which provides enough power to replace the overnight loss. 12 volt stuff has its own bank and charger that runs off the Outback inverter. Been using this simple system for 5 years now with many times at anchor for a week or more. John
    Mahalo V
    1974 53 Motoryacht
    Hull Number 406
    San Diego, Ca. Ready 32 Nordic Tug, Brunswick Ga.

  5. #5

    Re: Energy Efficiency and Solar Power on a 53MY

    Quote Originally Posted by Boatsb View Post
    I hope you're not using standard lithium ion cells. They burn long and hot and are not safe for that type of use. Also they need specific charge characteristics not available with your standard alternators.

    The idea is sound but if your not using the right gear your going to have problems.

    I sell a lot of liFePo batteries for marine use. There's not a 32 volt solution for a reason.
    Thanks, Scott. I'll be using LiFePo4 cells to make up a DIY 32V battery. They're 3.2V nominal so I should be OK with ten of them. I was thinking of going with 11 and only charging them to 90% but we'll see how it goes. They should hold 36 V in their full state of charge.
    Thom Price
    1984 Hatt 53 MY Tiramisù
    Harborview Marina, Baltimore, MD
    gondolaguy@gmail.com
    Liveaboard

  6. #6

    Re: Energy Efficiency and Solar Power on a 53MY

    I don’t understand the point of switching the water heater to 32v since you still have a bunch of AC appliances on board. It s going to put a lot of stress on your house bank whenever it runs. Down here in summer I often turn off the water heater when running full AC and cooking and if I forget to turn it back on, the water stays hot for 12 hours or so and reheats in 20 minutes.

    The best solution to cut down generator use is to set up an inverter off a dedicated 24v bank. Properly sized you could cut down generator usage to 4 hours on, 20 hours off. I ve done it on two boats over the years

    Nowadays with LEDs, more efficient heads and water pumps, your house system doesn’t use as much power as when these boats were designed. You re not going to gain much by messing with it. If you want to cut down Charger usage, then add a few panels but I doubt a modern charger will use more than $20 a month of electricity... is it even worth spending money on solar panels? Especially up north... solar panels only put out rated output for a few hours a day and only if angled toward the sun. I bet it will take years to recoup the cost with savings from not using a charger
    Pascal
    Miami, FL
    1970 53 MY #325 Cummins 6CTAs
    2014 26' gaff rigged sloop
    2007 Sandbarhopper 13
    12' Westphal Cat boat

  7. #7

    Re: Energy Efficiency and Solar Power on a 53MY

    Quote Originally Posted by Scarlett View Post
    We anchor out quite often and have been using 4 100 watt solar panels that charge our 32 volt bank. For us this is enough power to run our large refer and a smaller beer fridge plus toilets and misc stuff all day with a slight gain. We use the gen set mainly for cooking which provides enough power to replace the overnight loss. 12 volt stuff has its own bank and charger that runs off the Outback inverter. Been using this simple system for 5 years now with many times at anchor for a week or more. John
    This is great info. Thanks so much, John.
    Thom Price
    1984 Hatt 53 MY Tiramisù
    Harborview Marina, Baltimore, MD
    gondolaguy@gmail.com
    Liveaboard

  8. #8

    Re: Energy Efficiency and Solar Power on a 53MY

    Quote Originally Posted by Pascal View Post
    I don’t understand the point of switching the water heater to 32v since you still have a bunch of AC appliances on board. It s going to put a lot of stress on your house bank whenever it runs. Down here in summer I often turn off the water heater when running full AC and cooking and if I forget to turn it back on, the water stays hot for 12 hours or so and reheats in 20 minutes.

    The best solution to cut down generator use is to set up an inverter off a dedicated 24v bank. Properly sized you could cut down generator usage to 4 hours on, 20 hours off. I ve done it on two boats over the years

    Nowadays with LEDs, more efficient heads and water pumps, your house system doesn’t use as much power as when these boats were designed. You re not going to gain much by messing with it. If you want to cut down Charger usage, then add a few panels but I doubt a modern charger will use more than $20 a month of electricity... is it even worth spending money on solar panels? Especially up north... solar panels only put out rated output for a few hours a day and only if angled toward the sun. I bet it will take years to recoup the cost with savings from not using a charger
    Thanks, Paschal. Yes, I agree that the benefit has to be worth the cost. Remember that I'm paying $0.25 per KWH. That's more than twice the national average which means that I'll recoup the cost in less than half the time. Solar panels are getting cheaper by the day. I'm also interested in reducing my carbon footprint. (I know, buying a big boat probably isn't the best way to do that, but still anything I can do to reduce it doesn't hurt.) If I have enough panels to have a little extra after the batteries are full, a good way of using it is to store it as hot water. That's why the DHW is getting converted to DC, since I would have lower system losses by eliminating the need for an inverter to use it that way. Does that make more sense now?
    Thom Price
    1984 Hatt 53 MY Tiramisù
    Harborview Marina, Baltimore, MD
    gondolaguy@gmail.com
    Liveaboard

  9. #9

    Re: Energy Efficiency and Solar Power on a 53MY

    Good inverters have less loss that the line loss of DC.

    Don't reinvent the wheel.

    https://www.victronenergy.com/


    Look at their systems approach.
    Scott
    41C117 "Hattatude"
    Port Canaveral Florida.


    Marine Electronics and Electrical Products Distributor.

  10. #10

    Re: Energy Efficiency and Solar Power on a 53MY

    Can you clarify: are these Li-on batteries or LiFePo batteries? If Li-on then your tolerance for risk in much greater than mine!
    Michael & Beth
    Hull Number CV312
    63’ Cockpit Motor Yacht
    1986 model launched in August 1987

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