Solar Boat - General principles in selecting equipment

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  • Jrfrancis
    Junior Member
    • May 2016
    • 1
    #1

    Solar Boat - General principles in selecting equipment

    Hello all,

    I apologise if this question is very basic. Whilst not working in the industry, I have designed and built several boats often for river adventures etc. I am now starting to get interested in the concept of boats with sufficient solar panel capacity to keep it's electric motors charged allowing it (all things being equal) to run continuously day after day without charging from shore (or petrol generator etc).

    I'm initially thinking of putting a trial setup on a 16ft motor canoe that I have for a couple of days trip down a river, and then (potentially) building a more serious setup (such as a small houseboat) in a few years time.

    To start with, I envisage that the trial setup would utilise off the shelf products, such as a trolling motor, battery, panels, and any other ancillary items that are required.

    With basically zero electrical knowledge, could anybody share some general principles that I should follow? Such as what specs I should look for on the motor, battery, panels (or any suitably ratios of panel wattage to engine wattage). Also, any guidance of ancillary items would be appreciated as well.

    Kind Regards
    Tags: None
    • SunEagle
      Super Moderator
      • Oct 2012
      • 15126
      #2
      Hello JrFrancis and welcome to Solar Panel Talk

      There are a couple of forum members that have built boats of various sizes the include a solar / battery system.

      Here is the link to one of those threads

      My First Solar Powered Boat Project - Solar Panels - Solar Panels Forum
      https://www.solarpaneltalk.com/forum/off-grid-solar/off-grid-solar-panel-systems/12286-my-first-solar-powered-boat-project
      Discuss remote solar applications for homes, cabins, RV and boats. If you have a question on equipment for an off grid system, such as charge controllers or inverters, then post your question in this forum.

        Comment

        • Sunking
          Solar Fanatic
          • Feb 2010
          • 23301
          #3
          Originally posted by Jrfrancis
          I am now starting to get interested in the concept of boats with sufficient solar panel capacity to keep it's electric motors charged allowing it (all things being equal) to run continuously day after day without charging from shore (or petrol generator etc).
          Impossible. There is a very good reason you do not see solar powered Boats, planes, auto's, and trains.

          With basically zero electrical knowledge, could anybody share some general principles that I should follow?
          some simple physics and basci electrical power is what you are missing.

          Let's say you have a 12 volt Trolling motor. Say a very small motor that generates 30 pounds of thrust. FWIW at 12 volts 1 amp = 1 pound of thrust. You want to run it 5 hours at half power or 15 amps. 15 amps x 5 hours = 75 Amp Hours. At 12 volts is 12 volts x 75 AH = 900 watt ours.

          Now here is where it gets bad. You will need a battery, no way around it. Assuming you discharge that battery 80% means you need a 12 volt 125 AH battery. That battery weighs around 70 to 90 pounds in the canoe with you.

          Now to charge that battery with Solar panels you have to be able to find a spot where you can point the panels at the Sun and no shade from sun rise to sunset. It would take a 500 to 600 watts of solar panels. 500 watts of the most efficient solar panels out there would be about 11 ft x 2 ft x 2 inches and weigh around 70 pounds raising the center of gravity way up. It is going to be larger than the canoe.

          Here is the fun part. 15 pounds of thrust ain't going to push you very fast if at all. You could get out and push faster. You would be better off with a sail. Eitherway would require outriggers to keep you upright.

          Need real power. Would take at least 1 Hp to generate 75 to 90 pounds of thrust on a 12 volt motor is 70 amps or 5 times more power. So multiply everything by 5. It wil be as big as a house and weigh some 800 to 900 pounds on your canoe. Not possible.

          Just simple physics.
          Last edited by Sunking; 05-30-2016, 08:51 PM.
          MSEE, PE

            Comment

            • Rofisher
              Junior Member
              • Mar 2021
              • 1
              #4
              Dear MSEE, PE
              Thankyou for the excellent, frank and useful EE information about using solar power on the water.
              I'm proposing using a Minn Kota Enduro 30 C-2 at 3-4 speed (14-20 amps)
              I'm proposing two people in a lightweight (300 lb) 14' shallow-Vee al boat with a 100 watt PVC and two batteries, one a 31DC and the other 24M. Probably total weight 600 pounds.
              I'm proposing traveling about 6 miles in about 3 hours (yes I could walk faster, but not on water and not see what I'll be seeing).
              I'm proposing the PVC to AUGMENT, and recharge when stopped, my battery power.
              I'm assuming: PVC being 75% efficient, drawing down the batteries 25%, a moderate amount of sun.
              I'm assuming this is going to work. Yes, I know the acronym for assume, but hoping for the best.
              What are your honest and EE educated thoughts on this proposal?
              Thanks, Bob, MS in Plant Pathology from Penn State 1972

                Comment

                • SunEagle
                  Super Moderator
                  • Oct 2012
                  • 15126
                  #5
                  Originally posted by Rofisher
                  Dear MSEE, PE
                  Thankyou for the excellent, frank and useful EE information about using solar power on the water.
                  I'm proposing using a Minn Kota Enduro 30 C-2 at 3-4 speed (14-20 amps)
                  I'm proposing two people in a lightweight (300 lb) 14' shallow-Vee al boat with a 100 watt PVC and two batteries, one a 31DC and the other 24M. Probably total weight 600 pounds.
                  I'm proposing traveling about 6 miles in about 3 hours (yes I could walk faster, but not on water and not see what I'll be seeing).
                  I'm proposing the PVC to AUGMENT, and recharge when stopped, my battery power.
                  I'm assuming: PVC being 75% efficient, drawing down the batteries 25%, a moderate amount of sun.
                  I'm assuming this is going to work. Yes, I know the acronym for assume, but hoping for the best.
                  What are your honest and EE educated thoughts on this proposal?
                  Thanks, Bob, MS in Plant Pathology from Penn State 1972
                  The last post was from May of 2016 or about 5 years ago so it is an old one to dig up. Also while Sunking does come back to this forum it is hit or miss to get him to respond to a post.

                  Maybe others here on the forum will help you with your experiment.

                    Comment

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