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Old 28-03-2021, 19:19   #31
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Re: Solar Electric Catamaran Model

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Originally Posted by stark View Post
The issue is that a solar panel will not produce much electricity if even a small part of it is shaded. It has to do with the way the cells in the panel. are tied together. The mast shadow might be 2%, but the output of the whole panel might drop 90%.
That does not make any sense. I am experienced in electronics. I designed and manufactured circuit boards. I was an Engineering assistant at General Dynamics. I have three 12” x 36” solar panels at home, plus seven other solar chargers, and have been using various solar chargers for over 30 years. I fully understand the system. Your comment does not make any sense at all. Even a 50% shadow would not reduce output 90%. I have no idea what makes you believe that, but I would like to hear your scientific or engineering explanation.
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Maybe they'll figure this out in the future, but you'll probably just have more electricity overall by dropping the wind gen part
As pointed out, after researching recent technology, I probably won’t include a horizontal turbine. But like so many of the new solar boats, I might include some small traditional wind generators to provide energy at night or cloudy days to supplement solar.

You
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Old 02-04-2021, 16:05   #32
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Re: Solar Electric Catamaran Model

I put a forklift motor into a 16ft jetboat.

My experience on cooling is the added load of continuous water drag created a LOT of heat.

The only practical way I've found to remove the heat was with water cooling.

With your model you could invert the heat sinks, and cut through the hull for "keel cooling".

For the full scale boat, water cooled motors in the 100HP range are available.
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Old 02-04-2021, 20:43   #33
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Re: Solar Electric Catamaran Model

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I like the addition of a large vertical turbine.

Once you get the boat moving, the apparent wind should generate enough power to keep you going upwind forever.
A colleague of mine showed very convincingly that it is possible to use a wind turbine connected to a propeller to sail upwind. Harder to grasp is that it is also possible for the same machine to sail downwind faster than the wind speed.
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Old 02-04-2021, 21:06   #34
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Re: Solar Electric Catamaran Model

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I put a forklift motor into a 16ft jetboat.
My experience on cooling is the added load of continuous water drag created a LOT of heat.
The only practical way I've found to remove the heat was with water cooling.
With your model you could invert the heat sinks, and cut through the hull for "keel cooling".
For the full scale boat, water cooled motors in the 100HP range are available.
For the model it isn’t critical and not worth the trouble. Also, I am not going to cut those lovely custom fiberglass hulls. For the purposes of the model, and the short runs in the local ponds, I am sure it won’t be an issue.
The full size Cat will be a different matter entirely. That is a long ways in the future, and may depend upon what hulls I can get. On a side note, I had a chance to buy a pair of 60 ft Polynesian Concepts hulls for $5000. I stopped and looked at them on the way to the Rose Parade. I decided I had no place to put them at my house in San Diego so I didn’t get them. Imagine the Cat I could make with them.
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Old 17-04-2021, 18:01   #35
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Re: Solar Electric Catamaran Model

I finally was able to see how the model sits in the water. It is heavy at 10 lbs. But it seems to be balanced well, and the water line is well below the deck. I can easily trim it by shifting the battery etc.
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Old 18-04-2021, 11:49   #36
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Re: Solar Electric Catamaran Model

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Thank you for your concern.
After looking at hundreds of photos of powered Catamarans, the mast is far from common or traditional. Most didn’t have one. Even so, I put it on the model mostly for show, although a version of it may end up on the full size Cat.
I did the calculations and the largest shadow that mast could cast is 2.4% of the surface of the deck. Depending on the angle of the Sun, that would amount overall to perhaps 1% of the surface overall. Therefore the shadow is not an issue.
It is not about percentage. If one cell in a series of cells is shaded it will cut production on the whole string of cells, including other panels that are wired in series. If at all possible one should avoid any shading, especially in a situation where efficiency is so important. It takes a lot of power to drive a boat through the water at any reasonable speed, thus a lot of solar, which adds weight, which in turn adds resistance, which requires even more solar. Look at the Turanor solar catamaran, that's a lot of solar! I worked in solar for a number of years, if that lends any credibility to what I'm saying. Also remember the on a boat you will not have optimal angle of incidence on the panels, cutting efficiency even further, then you have to consider weather and available sunshine, and then consider how to store enough power for overnight and long periods of overcast. It would be important to have a source of backup power generation. I had a similar fantasy for a solar powered catamaran. Was a much greater cost and challenge than I originally anticipated. And then having a massive amount of electrical in a wet, corrosive environment is its own challenge. I hope you succeed because I'd love to see someone build a really good solar boat. Most of the solar catamarans on the market are woefully inadequate, you can tell just from a quick glimpse of the solar collector area in regards to the size of the vessel, but they rely on people having limited knowledge.
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Old 18-04-2021, 15:39   #37
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Re: Solar Electric Catamaran Model

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It is not about percentage. If one cell in a series of cells is shaded it will cut production on the whole string of cells, including other panels that are wired in series. If at all possible one should avoid any shading, especially in a situation where efficiency is so important. It takes a lot of power to drive a boat through the water at any reasonable speed, thus a lot of solar, which adds weight, which in turn adds resistance, which requires even more solar. Look at the Turanor solar catamaran, that's a lot of solar! I worked in solar for a number of years, if that lends any credibility to what I'm saying. Also remember the on a boat you will not have optimal angle of incidence on the panels, cutting efficiency even further, then you have to consider weather and available sunshine, and then consider how to store enough power for overnight and long periods of overcast. It would be important to have a source of backup power generation. I had a similar fantasy for a solar powered catamaran. Was a much greater cost and challenge than I originally anticipated. And then having a massive amount of electrical in a wet, corrosive environment is its own challenge. I hope you succeed because I'd love to see someone build a really good solar boat. Most of the solar catamarans on the market are woefully inadequate, you can tell just from a quick glimpse of the solar collector area in regards to the size of the vessel, but they rely on people having limited knowledge.
Thank you for your input. Considering that most solar panels of that size will be large enough where a 2% shadow will be significant, the mast would not be an issue. However, as noted, it was mostly for aesthetics and show. Also, solar panels will be selected for the required voltage, so none will be in series.
One modification I have considered for the solar panels on the cabin is a system of lifts, one on each side, that can tilt the entire array toward the sun using one, or two in conjunction. In fact many years ago, I worked on a system that did exactly that for 4’ x 8’ solar panels. The electronics for that control are very simple.
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Old 18-04-2021, 16:00   #38
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Re: Solar Electric Catamaran Model

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That does not make any sense. I am experienced in electronics. I designed and manufactured circuit boards. I was an Engineering assistant at General Dynamics. I have three 12” x 36” solar panels at home, plus seven other solar chargers, and have been using various solar chargers for over 30 years. I fully understand the system. Your comment does not make any sense at all. Even a 50% shadow would not reduce output 90%. I have no idea what makes you believe that, but I would like to hear your scientific or engineering explanation.
As pointed out, after researching recent technology, I probably won’t include a horizontal turbine. But like so many of the new solar boats, I might include some small traditional wind generators to provide energy at night or cloudy days to supplement solar.

You
If a panel has all its cells wired in series and you block all light to only one cell the output of the entire thing will be almost completely compromised. Experiment and you will see for yourself. Also worthy of consideration in regards to wind generation is that if you are going into a headwind the turbines wind resistance will rob more power than the turbine is putting out, especially considering that they are not 100 percent efficient, not to mention the inefficiency of converting the power generated into actual propulsive power, and furthermore the wind resistance of the vessel itself.
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Old 18-04-2021, 16:21   #39
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Re: Solar Electric Catamaran Model

Even a cursory look at the current state of PV panel development would show that significant advances in creating more shade tolerant panels are already available. The use of bipass diodes, half cell construction, and integrated microinverter tech are all helping to mitigate panel and array shading.

See solarnerd.com for discussion.
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Old 18-04-2021, 16:27   #40
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Re: Solar Electric Catamaran Model

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Even a cursory look at the current state of PV panel development would show that significant advances in creating more shade tolerant panels are already available. The use of bipass diodes, half cell construction, and integrated microinverter tech are all helping to mitigate panel and array shading.

See solarnerd.com for discussion.
This is true, but high end solar tech is expensive and adds complexity. A lot easier, more effective, and cheaper to simply avoid shading. There is no need for a mast like that anyway.


By that token you can get 40% efficient solar cells if you are willing to drop enough money.
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Old 18-04-2021, 17:35   #41
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Re: Solar Electric Catamaran Model

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If a panel has all its cells wired in series and you block all light to only one cell the output of the entire thing will be almost completely compromised.
What part of “Also, solar panels will be selected for the required voltage, so none will be in series.” Don’t you understand??????
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Also worthy of consideration in regards to wind generation is that if you are going into a headwind the turbines wind resistance will rob more power than the turbine is putting out, especially considering that they are not 100 percent efficient, not to mention the inefficiency of converting the power generated into actual propulsive power, and furthermore the wind resistance of the vessel itself.
That argument has already been proven to be false. “Sail boats” with wind turbines have been built that sail directly into the wind. That is a fact.
Hint: How do conventional sails create the power needed to move forward in a tack?
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Old 18-04-2021, 17:41   #42
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Re: Solar Electric Catamaran Model

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That argument has already been proven to be false. “Sail boats” with wind turbines have been built that sail directly into the wind. That is a fact.
Name ONE.
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Old 18-04-2021, 18:05   #43
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Re: Solar Electric Catamaran Model

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Name ONE.
Blackbird. But there are others.
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Old 18-04-2021, 18:07   #44
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Re: Solar Electric Catamaran Model

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Name ONE.
The same hint: How do conventional sails create the power needed to move forward in a tack?
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Old 18-04-2021, 19:16   #45
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Re: Solar Electric Catamaran Model

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What part of “Also, solar panels will be selected for the required voltage, so none will be in series.” Don’t you understand??????

That argument has already been proven to be false. “Sail boats” with wind turbines have been built that sail directly into the wind. That is a fact.
Hint: How do conventional sails create the power needed to move forward in a tack?

What size of turbine do you need to generate 10kw in kets say 10 knots of wind?
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