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Old 11-12-2014, 18:07   #16
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Re: Which solar panels- best / where to buy

unanchored,
Sorry to read of the theft of solar panels...
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Originally Posted by unanchored View Post
After leaving the boat In the yard for too long, we returned to find our 2 large pole mounted solar panels stolen. Now we need to get new ones but want to make sure we are getting good ones. Any suggestions on where to buy ( we are in northern FL ). The old ones charged 8 amps. Is there a brand that is typically used / better quality ? Any help would be appreciated !!!
1) First off, make sure whatever new panels you buy will match / are compatible with, your solar charge controller....
You made no mention of your controller, nor the Voc or Vmp, of the panels....(nor even their rated wattage)....

Your mention of charging at 8 amps, makes me think you might have had a pair of 75 watt panels....since you mention "panels" plural, rather than singular, I assume two panels???

If you're willing to change your controller (might be a good idea, if it's an older non-MPPT controller), then buying new panels to match your new controller will be easy-peasy...


2) Next, be aware that you CAN find bargains on-line and in some stores...but be aware that you usually get what 'ya pay for, so shopping for a bargain to save $20, might not be a good idea....


3) I recommend Kyocera brand....hands down the winner in my opinion....
No, not the absolute most efficient panel in the world, but certainly in the top few.....and very robust, and reliable....with excellent warranty, etc....
(and if you get Kyocera panels in 140 watt sizes, or smaller, they are all nominal "12-volt" panels, with Voc ~ 21-22v and Vmp ~ 17.5 - 18v....allowing any charge controller to be used....)

If you had a pair of smaller panels, such as a pair of 75 watt panels, you may have difficulty finding panels exactly matching the old ones...
Think "Up Size"!!
Don't forget that the panels can extend over the transom and/or toerails, so you can up size if you need...


4) If you're looking for sources in Florida....
Here are 3 that I have personally done business with, and have been completely satisfied...

E-marine Inc...
Marine Solar Panels For Sale - e Marine Systems
Kyocera Solar PV Panels For All Environments - e Marine Systems


Hot Wire Enterprizes....
Kyocera – svHotwire - 727-943-0424 | svHotWire



Salt Services....
SALT Service Inc - Marine, residential and motor coach alternative energy systems
SALT Service Inc - Marine Solar PV Power Panels Energy



I hope this helps....

Fair winds...

John
s/v Annie Laurie
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Old 13-12-2014, 08:29   #17
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Re: Which solar panels- best / where to buy

I stick by my small panels are better. Small panels can always be combined to fill a larger area. MPPT controllers are a must on a vessel. You can't just throw away what little power you can get from your panels. My 60 Amp MPPT controller doesn't have a fancy display, but it was only $80 on ebay from a place in CA. Smaller panels do not have thinner glass, which makes them less susceptible to breakage.

What I do need to do with my cheaper panels is replace the wires coming out of the junction box with marine wire. Just a little soldering. After doing that, I will coat the contacts and the diode inside with epoxy to protect them from the salt environment (since the current at full output is just 1.4 watts, the diode will not get very hot---and with the losses, it will not even be 1.4) Each panel has its own diode, so when shaded (or broken), it doesn't become a 'load' on the whole system. Yes, panels become a drain when not working putting out voltage--hence the diodes on each panel.

All monos available today are 18% efficient or better. Getting the best at 22% might not make that much of a difference. Poly has always been wrong for a boat. Efficiencies have never been good enough. No matter what: 100 watts is 100 watts. It is the only way to compare. Every panel is going to have losses for cloud cover, angle of incidence (direction to the Sun), and temperature. All mono cells are made of the same thing, and made pretty much the same way (my Dad was a semiconductor device man) The significant differences between panels is between mono, poly, and thin film. While the losses might differ by a few percent would it be worth twice the price? You could look for 'solar' glass, which transmits more energy through the glass. Start with mono, modify as needed. My panels were $1.46 per watt delivered. Mounting and wiring extra, of course. Price was my main concern. With my catamaran roof, area was less a concern.

Most important is efficiency of use. Everything must be LED (with voltage spike protection). Spend the extra to get lights that use less power. Incandescent anchor lights are 10 watts. LED run 1 to 4 watts for the same thing. Get as close to 1 watt as possible. Use less, and the power from the panels will go farther. Do this everywhere. It adds up.

As for books on the subject, try Amazon. I have 'The Solar Boat Book' A little outdated, but a good read. Get more than one book. Take from each what will work for you. No one has all the answers for everyone in one place.
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Old 14-12-2014, 15:46   #18
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Re: Which solar panels- best / where to buy

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Are there any tests in which solar cells (or panels) have been tested with regards to:
- efficiency with regards to illumination
- efficiency with regards to temperature
- efficiency with regards to sun angle?
The short answer is 'yes'. The longer answer is 'Yes, but only a few panels are willing to subject themselves to these tests'. It would take more space (and probably more readers' patience!) than is available here to go into each area in detail, but here's a sampling of what's out there and independently verified...

Temperature Coefficient Power (P) shows power degradation for every 1 degree C over 25 degrees. SunPower's rating (-0.38%) is one of the best on the market, with the average of the panels tested -- There are many 'cheaper' panels untested -- between -0.40% & -0.50%. i.e. for every one degree, the average panel losses 0.5% where SunPower only loses 0.38%. SunPower's new test modules have dropped to a -0.30% temperature coefficient which is the best performing crystalline silicon panel on the planet. The only thing better is thin film, which has really low efficiency (taking up lots of space).


In terms of ‘real world’ performance, the most reputable tests are done by Photon. This is not on marine craft, but they are scientific conditions where they build systems of exactly the same rated size with the same inverters and conditions etc, and they are designed to see who yields the most. In the latest tests (released Jan 2013) SunPower took out the top 3 positions, with the 327W modules that we market being the highest performer.

As for low-light conditions, Photon has done other tests (published – June 2012) that once again prove SunPower's claims to be the best available:
“The [SunPower] device has a nearly straight efficiency curve with almost no change in the medium-to-high irradiance range and only a minimal drop at low irradiance levels. No other module tested thus far has such an efficiency curve.”

If each of these efficiency differences sound small, they make a big difference over whole panel areas and over extended periods of time.


So again, and with great respect to others here, simply comparing 100 Watts to 100 Watts is a very incomplete comparison.

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Old 14-12-2014, 19:27   #19
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Re: Which solar panels- best / where to buy

Hi

Actually, I took look at the specs on my 'cheap' HyPower solar panels and the drop in efficiency per degree C is .38%, too. Strangely, they are priced quite a bit more than when I looked at them. Maybe prices in the solar market is on the upswing---who knows. The panels you are promoting are at a very good price and come with the advantages you have stated. Of course, larger panels have always been cheaper per watt. Strangely, the specs (from the picture of the bottom side of the panel state that it consists of 9 cells when it should say 36 cells.

I went with the smaller panels for the shading and breakage reasons. And, of course, I need to unsolder the wires going in and replace them with marine wire. The SunPower panels would certainly be a excellent and viable option for many. Kudos for bringing them to the forum. There are many factors that the individual has to consider when bringing the oldest form of long distance travel (sailing) into the modern era. Thanks for your input.

Remember the key: Use as little power as possible by going LED for lights and Broadband if you are going radar. Less need means your solar will go farther.

Enjoy the day,
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Old 15-12-2014, 16:38   #20
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Re: Which solar panels- best / where to buy

Thank you to everyone for sharing your experiences and giving your input!

D&D- I was looking at the sunpower online but the only one I found was a 327 w measuring 1m x 1.5 m ; are there different models?

Right now I'm looking at a renogy 100w for 120 bucks delivered




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Old 15-12-2014, 16:58   #21
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Re: Which solar panels- best / where to buy

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D&D- I was looking at the sunpower online but the only one I found was a 327 w measuring 1m x 1.5 m ; are there different models?
No...and that (as we mentioned earlier) is the only disadvantage we can think of re the SunPower panels. There are some 'soft' panels of other sizes that use SunPower cells (possibly European made?) but the last time we looked they were prohibitively expensive.

We wish you well for your installation!
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