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Old 23-02-2012, 04:00   #136
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re: Best Solar Panels For The Buck

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Originally Posted by s/v Jedi View Post
I think you will need to test like Mark did: at least a week in one configuration followed by the same period in the other configuration. You need stable weather too so that the average sunlight received is the same over both test periods.

or....

you make a test setup in a controlled environment: dark shed or cellar with panels and artificial light source. Emulate shading with cloths on the panels etc.

ciao!
Nick.
I think I came up with a test method that might work. At intervals of approximately 30 minutes I switch back and forth between parallel and series. On these occasions, I record the collected Ah (one of the variables output by my controller) and time of reading. I then calculate average Amps during the interval by dividing the Ah accumulated over the interval by time in hours. This method will smooth out the erratic changes in output caused by cloud cover. Hopefully, the effects of cloud coverage and effect of boat orientation on shading will average out between series and parallel over the course of a day to make the comparison meaningful.
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Old 23-02-2012, 05:34   #137
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Wink re: Best Solar Panels For The Buck

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A few other points this raises. This example is with Pete's 18v nominal panels. On 12v nominal panels, this example would produce an optimal output around 12v, which wouldn't be high enough to charge your batteries if the controller can't boost it!
Thanks again. I just now had a chance to study this posting. You've answered my question about shading of one substring on my panels in parallel. They will do better than a similar situation with nominal 12 Volt panels provided the MPPT controller is intelligent enough to pick the right peak. The Morningstart TriStar 45 does a complete scan from 0 to Voc so it is unlikely to miss it I have read that other controllers do a so-called dynamic scan which only looks at the nearby Voltages. They would likely miss it.
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Old 24-02-2012, 15:01   #138
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re: Best Solar Panels For The Buck

Using the test method described in post 136, I ran some repetitive tests of serial vs parallel under heavy shading conditions. While the shading was highly variable as the boat swung on its mooring, I did record the number of cells shaded in each substring of 18 cells. The number of cells listed is in the order from forward to aft. The panel is indicated as port and stbd. In these rather short term tests it appears that parallel collects on average of about 50% more current.

I have attached both the spreadsheet used to calculate the average current as well as the graph showing power output and array voltage.
Pete
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Old 24-02-2012, 18:35   #139
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re: Best Solar Panels For The Buck

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Nick, the PDF file was created with "Acrobat version 0.0" in the file attributes. I've used plenty of Macs, *nix boxes as well. They're no better than Wintel PCs, just different. When Mac was 3x the cost of a PC and only had 1/3 the number of mice buttons, it didn't earn any converts. If it makes you happy, great. It's a computer designed for folks who don't want to know how to shift gears or change spare tires, which is why Apple and the AAA have both been very popular among certain demographics.

If Apple made solar panels, they'd be sealed, with proprietary output plugs and requiring the use of Apple-only controllers and Apple-only battery banks, and you wouldn't be allowed to discuss configuration or diode arrays, under threat of lawsuit for "jailbreaking" your panels.

But we're talking about technical issues here, so no doubt all the Apple enthusiasts have been scared away, except for you.
Like I said, I used to use PC. In those days I was a real man. Used to cold shower, run bare foot over brocken glass and bang my head against the wall. Never knew there was life without pain. Now sadly as a wuz, I just use my Mac and then enjoy life.

OK I drive a Toyota as well. Sadly no longer do I get to work at fixing it every weekend. Your right my life sucks!
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Old 24-02-2012, 19:01   #140
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Originally Posted by NorthPacific

Like I said, I used to use PC. In those days I was a real man. Used to cold shower, run bare foot over brocken glass and bang my head against the wall. Never knew there was life without pain. Now sadly as a wuz, I just use my Mac and then enjoy life.

OK I drive a Toyota as well. Sadly no longer do I get to work at fixing it every weekend. Your right my life sucks!
+1

Also, Mac has a real BSD Unix under the hood...

Anyway, PDF shows for us, others still trying to open

cheers,
Nick.
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Old 26-02-2012, 04:11   #141
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re: Best Solar Panels For The Buck

I recalculated the overall series and parallel Amp-hour outputs in, I believe, a more accurate way. It reduced the percent difference in favor of parallel from 56% to 40%; still a considerable difference. The new method weights the intervals according to their length rather than treating all intervals equal. I show both calculations in the attached spreadsheet for comparison. Comments welcome.

As an aside, I've discovered that when the wind comes from the prevailing direction just South of East, I get significant shading most of the day on the port side panel from the wind generator and its mast. What makes it particularly nasty is that the shading cuts across all 3 substrings. Despite that, I do not believe that any substring is being bypassed. I base that opinion on the fact that the array Voltage is 50-55 Volts while in series mode (see the attached graph). This suggests that both panels are contributing to the output. I wonder if the loss in solar power is compensated by the output from wind generator? I think not, however, the wind generator does create output on occasions when there is no solar to speak of. Knowing what I know now, I'm not sure if I would have installed the wind generator?
Pete
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Old 13-05-2012, 05:11   #142
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re: Best Solar Panels For The Buck

We're getting ready to put the boat on the hard for the hurricane season. What to do with the panels? We'll leave them in place, but should we cover them to prevent collection or simply disconnect them from MPPT controller and let them sit at Voc? We're afraid to leave them in operation without any load whatsoever for fear of overcharging our 4 golf cart batteries.
Pete
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Old 13-05-2012, 05:34   #143
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re: Best Solar Panels For The Buck

Pete, a good controller will shift to float mode very early in the AM if there's been no load. The Blue Sky senses the current needed to get to your setpoint voltage. When the current gets down to the value you've set, it backs down to float voltage, which shouldn't damage your batteries at all. We often leave Ocelot for weeks or even months while we're at home or on a road trip, & we never even consider disconnecting the solar array.
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Old 13-05-2012, 06:44   #144
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re: Best Solar Panels For The Buck

If your worried about having the system on then pull your fuses and hang a few VW solar panels.

Haul Out, On The Hard, Antifoul & Winter Storage
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Old 20-05-2012, 22:27   #145
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re: Best Solar Panels For The Buck

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Hi Cotemar,

I know you and some other folks got some SunPower panels, but I don't think they sell to boats anymore.

I called two local "premier dealers", and was told that they only sell the panels as part of a complete install package to residential or commercial folks. One even recommended I buy the Sanyo HIT 225W panel. I then called SunPower directly, and the agent I talked to said the same thing. When I asked him if he realized that his panels were on PlanetSolar's RTW solar boat, all he said was "yeah"......

SO, being a stubborn guy when he's getting told an answer he doesn't like, I "liked" them on facebook and posted the following:
"Hi, I am very interested in SunPower solar panels for an installation on a sailboat. However, when I called two authorized dealers I was informed that they could not sell panels unless installed as part of a residential system. Is this correct, or is there another way to procure these panels? The high efficiency rating of your panels is perfect for the limited space typical of a marine environment, which is probably why PlanetSolar has your panels on their around-the-world boat! How can I buy some of your panels?"

....and got no response. I hate having to work to spend my money, so I'm going to go with the Sanyo model. The SunPower would have been a perfect sizing and wattage, but the Sanyo allows me to better add more panels later based on available "real estate".

Unless you can PM me with how to get two 240W E19's... I could even make a pair of 320W's work..

I do have to chuckle and note the irony that the company that makes the solar panels on PlanetSolar's RTW boat won't supply to boats....!

Frank
Please PM me also ---I also would like some of these perhaps we could make an order together I need 3 of them any leads - South Florida??
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Old 21-05-2012, 01:02   #146
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re: Best Solar Panels For The Buck

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We're getting ready to put the boat on the hard for the hurricane season. What to do with the panels? We'll leave them in place, but should we cover them to prevent collection or simply disconnect them from MPPT controller and let them sit at Voc? We're afraid to leave them in operation without any load whatsoever for fear of overcharging our 4 golf cart batteries.
Pete
With the good controllers you are better leaving them connected. I lower the voltage set points, particularly the boost voltage when I am away with no load.
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Old 21-05-2012, 10:08   #147
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re: Best Solar Panels For The Buck

Ram,

For SunPower panels you can call local electrical distributors. Panel installers do not make any money selling panels, so will not sell you any.

Here is someone in Florida that has a seller you can contact.

If you guys are looking for SunPower panels contact Kent at Salt Service out of the Florida Keys. These guys have been great and they are very knowledgeable regarding boat installs. Apparently some guy just put 6 e19 320 panels on his Lagoon 50.

kentl @ saltservice . com
305-289-1150

Gene
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Old 21-05-2012, 11:45   #148
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re: Best Solar Panels For The Buck

One has to wonder. On a logical planet, SunPower would only stop selling panels for marine installation if they were seeing large and expensive warranty failures from that marine installation. Making it a good idea not to use them no boats.

No?
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Old 21-05-2012, 12:07   #149
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re: Best Solar Panels For The Buck

SunPower has never sold to the marine industry.

Everyone's using them on boats because they are putting out 240 watt at 31" x 61" inch at only 33 lbs. Only Sanyo panels come close to that.

The SunPower 327 watt is 41" x 61" inch and 41 lbs. Sanyo does not make a panel in this wattage.

Only one or two campanies warranty panels for marine use.
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Old 21-05-2012, 12:32   #150
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re: Best Solar Panels For The Buck

Sanyo VS Sunpower

http://www.sunwize.com/documents/San...wr240_4-11.pdf
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