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Old 01-02-2011, 04:35   #16
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thank you that is exactly what i was looking for.....i think i will go wtih 6 130 watt panels.....i have the room....i hope it will be able to give me almost all of my energy on average
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Old 01-02-2011, 04:54   #17
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The biggest variable is the location and time of year. In the tropics during winter you should get about 150 AHrs on average during winter. I have not cruised the tropics in summer.
In the Med in summer you would get 250Ahrs a day, but the tropics have worse insolation values than the sub tropics during summer so my guess would be 200-220 AHr.
The above figures are for a 12v system with 780W solar. Half the numbers for 24v
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Old 01-02-2011, 10:04   #18
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780 Watts in panels divided by 12 volt system equals 47.3 Amp per hour and if trading in at "5 hours of sun" (a sunny location in the tropics) per day we arrive 240 Amps into the bat each day.

Allow for the regulator (unless you have a MPPT), allow for all the losses etc you may get up to 200 Amps each sunny day, more if you can angle the panels, if they are unshaded and if you have a quality regulator.

Now where will you place the 780 Watts of solar? You have a power cat I guess?

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Old 01-02-2011, 10:11   #19
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BTW then also trade in the fact that there will be countless sunless days in a row and you have to have an alternative source - wind, alternator, genset or a fuel cell.

(Or just some paraffin lamps or plain candles if that's what your lifestyle is ... but I bet it is not ... since you need SO MUCH energy in the first place).

Thus, trade in a genset I guess, as a back up, or a dupy alternator/regulator combo.

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Old 01-02-2011, 10:57   #20
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Facts and figures are all well and good....then nature sends a week of dark clouds and tropical rain. Then we take on some glamor girl or pretty boy that can't live without kilowatt-hours of energy...life support by Exxon. In other words: you'll just have to try it an see. I can just eek by with 250W of solar, never running the engine, efficient fridge, no freezer, LED lights, frugal autopilot, in the deep hot tropics.
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Old 01-02-2011, 11:56   #21
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cat49,

You could go with a few SunPower (238 0r 318 watt) panels that are a lot smaller and lighter.
Use a Blue Sky MPPT controller and you would have a better and cheaper system.

Solar Panels for Your Home

Blue Sky Energy Inc. | Our Products

Project start Solar Panels and Associated Systems

On the Bimini Solar Panels and Associated Systems

On Tilting Davits Solar Panels and Associated Systems

Mark
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Old 01-02-2011, 13:33   #22
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I have 600 Watts charging through an MPPT charge controller.

In the Queensland tropics this year I never saw one single completely sunny day. We had a best days charging of 200 amp/hours into 12 volts

Just out of the tropics, when we finally did get a sunny day, we say 225 amp/hours - batteries needed some charging after several rainy days.

In Sydney we're getting full sunshine, but lower angles, probably could achieve around 180 amp/hours per day, but the controller is going into absorb and float modes, so limiting charging.
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Old 01-02-2011, 13:53   #23
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Cat49

out of interest can you tell us the make of catamaran
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Old 01-02-2011, 14:12   #24
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You have the room to mount SIXTY- PLUS square feet of solar panels? six panels, each five feet long and more than two feet wide? Conceivably, i suppose you could mount them on a bimini, providing your bimini is at least 13 feet wide, and you are willing to accept that you will lose performance due to boom shadowing.
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Old 01-02-2011, 15:09   #25
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Quote:
Originally Posted by Cotemar View Post
cat49,

You could go with a few SunPower (238 0r 318 watt) panels that are a lot smaller and lighter.
Use a Blue Sky MPPT controller and you would have a better and cheaper system.


Mark
Hi Mark, what is your take on this:

I just contacted SunPower and two of their local dealers. They verbally claim they will NOT (emphatic) warranty SunPower solar panels that are 1. not dealer installed, or 2. not installed on a grid. Their written warranty excludes any installations other than authorized installer, and limits their power output warranty of 25yrs down to 12yrs for any mobile installations.

Furthermore, the installer says the panels are positively grounded and the costs and difficulty associated with converting to negative grounding are significantly higher than installing normal negative grounded panels.

-Brent
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Old 01-02-2011, 16:00   #26
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The numbers can get so confusing. They rate Solar panels in watts, but that isn't @ 12V. (It is probably @ about 18V, and the V is marked on the panel back's label.) Most good panels are between 17 & 19V, because the voltage goes down when they get hot for one thing. That's why ventilation under them is important. Also if one uses multiple panels all spread out, a "shotky diode" in each panel's + wire is a good idea, to keep the shaded one from backfeeding. (There goes another .5 V of loss). You lose a bit on the charge controller and wire run too!

A FULLY CHARGED 12V wet battery, (AT REST for hours), has a resting V of between 12.6 and 12.7V
This is why the panels start out with a high voltage, so when the losses are figured in, the charge going into the batteries is at least 14V, and the charge controller keeps it from being TOO much, or for TOO long.

Our 280W of solar panel power total, from 4 panels, well separated, and one usually a bit shaded... Give us a max of about 60 Amp/Hours per day on a REALLY good day. Average is about 50 A/H... (between 30 and 40 A/H per day, on dark cloudy days) No sun, cloudy, but BRIGHT skies, still give plenty of output!

Our daily usage is about 35 Amp Hours, so in the rare case that it looks like we might not get fully charged, I tilt the aft panel every few hours, to track the sun. I can get about 10 more A/H this way!

It is best to figure your "normal" A/H per day need, and have twice that solar panel A/H per day available. This keeps you covered on cloudy days.

Also... Some people say: If they make them work at night, I'd buy one... They DO work all day and night, in conjunction with a large battery bank. We use daily, about 35 amp hours, out of about 350 amp hours available in the house bank. So the boat actually IS being run by the sun at night. A large enough battery bank, relative to the need, and you are good for even DAYS of very very cloudy dark skies.

Hope this helps. Mark
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Old 01-02-2011, 16:19   #27
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has anyone used the SunPower E19 Series panels on their boat? if so what do you think/know about them.
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Old 01-02-2011, 16:25   #28
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I should add... We do have a water maker, a fridge, watch movies, with sound through the stereo, have 9 fans, 17 cabin lights, run two anchor lights all night, etc. (All VERY energy efficient stuff, however.)

We lived on and/or cruised full time for 12 years, but most of that was NOT under way, it was "on the hook" in some nice place. Of that 90% spent on the hook, of those 12 years, we only had to run the engine for power about 10 times a year.

At sea this was not the case! Then the Radar, VHF, SSB, autopilot, and at night, Navlights are added. This can easily double our load. When at sea, and doing overnighters, we would have a deficit. To avoid this, each morning under way, we would crank the engine at 5:00 AM, and run it for an hour. With our 55 A alternator, and our battery at its 24 hour lowest, (where a battery really accepts the amps), this 1 hour run would put in about 35 A/H. The other 35 amps needed to top off the batteries, would be done by the solar over the day.

So, doing overnighters, we run the engine 1 hour/day. We're island hoppers... Since we only average about 25 overnighters a year, it only made sense to set up the system for our NORMAL daily load. Ocean crossers, that want to go all solar, need a lot more panels than we have, if they don't want to run the engine at all!
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Old 01-02-2011, 17:15   #29
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IQ Solar Ultralight weight panels

has anyone heard of these panels? they are supposedly designed for ultralight marine use....does any know anyhting about them?

http://www.myboatsgear.com/mbg/product.asp?prodID=1858
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Old 01-02-2011, 17:25   #30
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Some Minis use the IQs. I have run thru the specs and did not find anything oh so special there. Still, they are supposed to be decent - waterproof, reliable, etc..

The SunPowers like these:

SVB: SUNPOWER solar module from 699,90 €

are way cool - they pack 95 Watts in a frame that normally gives only 75 Watts - good use of space, if a bit more expensive than average, probably worth it when space is an issue.

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