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Old 10-04-2007, 14:42   #1
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Solar Energy

Hello, we would like to boost our energy output on a yacht in Croatia with solar power a bit. We cannot go the the lengths of a davit arrangement at the stern, and were thinking of perhaps a flexible panel to lie on the cabin top in the sun, or one to hang from the life lines on the sunny side. Could anyone give any suggestions of the easiest way to achieve this, and also would anyone have any idea of how many amps a sterio, or more importantly an electric fridge, just an average sized fridge on a 37 foot Jeanneau would use. Thank you
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Old 10-04-2007, 15:45   #2
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A 12 V Adler Barbor averages about 50-60amps/day. That should probably be the number you use. As far as the flexible panels, I honestly think you will be dissapointed. You should make an electrical budget and factor in how often you want to recharge with a genny/main. Once you know that, it will give you the power to make an informed decision. However, let me just say that most people without a watermaker will burn about 150 amps/day. With a WM, 180. Maybe you are less?? I know that is what we burn.

Dollar for dollar, you are probably best served with a wind generator. Contrary to what some say, solar is awesome and I am very pleased with my setup. But without a solar mount, etc... you will be dissapointed in my opinion.

Bottom line: I do not think the flexible panels work well and are a waste of money. Others may dissagree, just giving you my thoughts.

- CD

PS Here is my setup:



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Old 10-04-2007, 16:36   #3
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Annabel, if you do a search on this forum for solar panels you will find a great deal of information that should help you make a decision. Lots of pictures of intallations in the photo gallery. As a matter of fact if you scroll down to the bottom of this page you will get some links to start off with.

CD, those are awful large pictures for folks without high speed internet.
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Old 10-04-2007, 17:50   #4
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Originally Posted by Annabel
Hello, we would like to boost our energy output on a yacht in Croatia with solar power a bit. We cannot go the the lengths of a davit arrangement at the stern, and were thinking of perhaps a flexible panel to lie on the cabin top in the sun, or one to hang from the life lines on the sunny side. Could anyone give any suggestions of the easiest way to achieve this, and also would anyone have any idea of how many amps a sterio, or more importantly an electric fridge, just an average sized fridge on a 37 foot Jeanneau would use. Thank you
I haven't installed panels yet, but I've been doing some research towards installing some. One of the things I found was that the output of flexible panels is much lower than the rigid. Just did a quick look at Alternate Energy, an Iowa 20 watt flexible panel is 12"x73" (overall), that's 44 sq. inches per watt and costs $411.
A 20 watt rigid panel is 16 sq. inches per watt (overall). A BP 40 watt rigid panel costs $377, it's 25.8"x21.1", so is 14 sq. inches per watt (better probably because I'm using overall dims).

So in this case a rigid 40 watt panel is 2/3rds the size of a flexible 20 watt panel, and costs about the same.

Size is important because solar output is limited. I didn't see any discussion on flexible panels in a search of the forum, but I'm sure that there is real world experience discussion about output in this forum. That being said, Nigel Calder's book says to estimate panel output at rated power for 4-5 hours per day. So a 40 watt panel, using the 4 hour estimate, gives a little over 13 amp-hrs per day. To keep up with the fridge, with CDs estimate of 60 amp-hrs, you would need about 180 watts of solar panel. In a sunny place less.

John
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Old 10-04-2007, 18:54   #5
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The flexible panels produce less maximum output, but they are shade tolerant. So if you have a small shadow on the monocrystal panels, like the shadow of a topping lift, the output can go below what you will get with flex panel. The flex panels therefor give you more mounting options because of their shade tolerance. Check the FAQ at SV Hotwire.
Solar Panel FAQs

Like everything else on a boat, it's all trade-offs.

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Old 10-04-2007, 20:46   #6
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Got 150 watts on the back of my boat.

Great when the sun is shining.
Have seen output greater than rated:

10.3 amps Vs. 8.8 as per the specs, in the Bahamas in June.

During rainy and cloudy days however they don't do much at all...(Duh)
The rainy days usually have some wind however.

A good combo would be solar and wind.
Been shopping around for a good wind generator, but have not decided on what, where and when yet.

(I think my research dragged up the KISS as a top choice, but the Air-X was $400.00 cheaper, so I am still pondering.)

The biggest problem on my 33' cutter is where to put the wind-mill, without shading the existing panels or maiming people, and also without extensive engineering with a $5,000.00 arch or a tall pole that would blow away in a hurricane.
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Old 10-04-2007, 21:53   #7
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Originally Posted by CSY Man
http://www.cruisersforum.com/gallery...500&userid=308

Got 150 watts on the back of my boat.

Great when the sun is shining.
Have seen output greater than rated:

10.3 amps Vs. 8.8 as per the specs, in the Bahamas in June.
I did a little search before coming back here, but didn't find a conclusive answer. The real question in my mind is how good is the Calder multiplier factor. You have gotten greater than rated amps, but for how long? If someone has tracked amp-hrs put into batteries per day using something like a Link monitor and averaged that over a month, that would be an interesting number.

John
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Old 11-04-2007, 00:17   #8
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John...just a back of the envelope number but it seems like about 1/3 of the wattage is what you'll get in amp hours delivered into your batteries with fixed panels. With an MPPT controller you can improve that to about 40% of your wattage.
So...a 100W panel can get you roughly 33-40 amps a day in sunny weather.
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Old 11-04-2007, 07:20   #9
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You have gotten greater than rated amps, but for how long?
Not long....

I belive the panels are rated from the manufactor to deliver a max of 4.4 amps around the Latitude of New York.

On sunny day in June in the Bahamas, with clear air and the sun 90 degrees overhead, I have seen quite a bit more:
(Two 75 watt panels, rated output 8.8 amps, max observed 10.3 on the Xantrex Battery Monitor)

The peak output did not last all day, but if there ain't no clouds, ya could expect to see it severeal hours.

As far as daily output..?
Not really tried to measure it with any accuracy, would have to turn the 12 V panel off, have the battery bank somewhat discharged then let the panels charge all day and read total amp hours after the sun sets.

Guessing 55 to 65 amp hours on a good day.

If I could angle them panels, I would have more output, but decided to keep 'em fixed for simple and sturdy installation:

They did survive hurricane Wilma without moving an inch...
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Old 11-04-2007, 07:30   #10
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...The real question in my mind is how good is the Calder multiplier factor ...John
Calder's 4 Hour multiplier is a (somewhat arbitrary) rule of thumb, intended to account for "average" cloud cover. It's a very rough guide to depreciating for unknowable conditions.

See also Moby Dick’s comments regarding "Bounded Rationality".
Raymarine or Furuno? Recommendations?
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Old 11-04-2007, 07:35   #11
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I have an AIR-X mounted on a 9' pole on the stern, bought it from "Sunelectronics" in Miami. I have been very happy with it's performance.
BTW it survived "Wilma" at anchor in Miami.
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Old 11-04-2007, 09:41   #12
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What kind of out put are you getting out of your Air X at say, 10 knots of wind. I only see about 1 - 1.5 amps.

Keith
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Old 11-04-2007, 10:32   #13
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I haven't checked the actual out put. I'm running my Fridge, TV and computer through the inverter, the Air-x is keeeping up with it.
My battery Bank consists of 4- 6volt golf cart batteries (420 AH). I rarely have to run the generator.
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Old 11-04-2007, 11:28   #14
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If someone has tracked amp-hrs put into batteries per day using something like a Link monitor and averaged that over a month, that would be an interesting number.
Hmm, that is doable with the Xantrex Battery Monitor
if ya hook it up to a laptop PC...Which I have not done yet.

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Old 14-04-2007, 17:22   #15
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Don't know anything about wind conditions in Croatia. But, I'm inclined to agree with Cruisingdad. To get the kind of output you want, a wind generator is more cost effective - of course, both wind and solar is better still. A wind generator requires a properly braced ridgid pole, but this is far simpler and less expensive than a radar arch.

We had an Air Marine wind generator on a 34 footer in the Caribbean with an Alder Barber 12v system and never ran the engine to charge batteries (except when running the water maker). Of course, it's always windy in the Caribbean; I have an uncanny ability to find the 'sheltered' anchorage where it's windy anyway; the wind is always from the wrong direction; and I am the only person to ever sail from Barbados to St. Vincent against a 15 knot west wind when everyone else claimed to have 5 knots out of the east - charged them batteries right up.
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