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Old 08-01-2016, 00:02   #1
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Should I buy these solar panels?

ECO-WORTHY 600W 24v Off Grid Tie Complete Solar Panel Kit: 4pcs 160W Mono Solar Panels+20A MPPT Controller+Solar Cable+MC4 Branch Connectors Pair+Z Bracket Mounts

If you look these up on Amazon they look like they're not a bad deal. I have room for them, why shouldn't I buy these?

I'm just trying to learn about which panels I want to buy so, no need to be gentle and/or spare my feelings. If its a stupid idea go ahead and tell me!
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Old 08-01-2016, 03:22   #2
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Re: Should I buy these solar panels?

No specs on the charge controller, so no idea if it will match your particular battery setup, or ANY setup for that matter. I would disregard it completely.

The advert is a bit suspect, the rating of the controller changes throughout the advert text. At one place it says 45Amp, another says 30amp, and your text, oddly enough, says 20Amp. So which is it? Or did I get the wrong system?

Here's where I ended up...

Amazon.com : ECO-WORTHY 600W Monocrystalline 12v 24v Off Grid Battery Charging Solar Panel Kit: 4pcs 160W Mono Solar Panels+45A Charge Controller+Solar Cable+MC4 Branch Connectors Pair+Z Bracket Mounts : Patio, Lawn & Garden

None of the numbers add up either. If those are 160 watt panels then the theoretical maximum output is 640 watts, which would need a nominal 53Amp controller to get all the power. (Actually more like 60amp, but I am just sticking with theory at this point.)

And 3KW hours a day...?! Phhtt! On Mercury maybe... on a good day.

I think packages like these are just a bit too suspect for my taste. I have no problems buying un-branded panels (of course I'd love to buy the good ones) but the whole system feels really undocumented and uncertain.

Sorry... back to the drawing board.

Matt
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Old 08-01-2016, 19:16   #3
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Re: Should I buy these solar panels?

All good points, thank you!

What about other issues like the physical construction of the panels? Is it normally good enough that a panel is set in an aluminum frame or or should I be looking at some specific values for deflection under load?

Are there specific mounting concerns or do you typically just adapt to whatever sort of frame the manufacturer came up with?

The MC4 connectors seem to be an industry standard, is that right?

I've noticed too that any time you go over about 220 watts it seems like the price drops on a "per watt" basis. The target market must be changing to more "sane" landlubbers! Are there any potential problems with carrying panels this size as opposed to carrying several smaller ones?

Thank you for all of the good advice!!
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Old 08-01-2016, 22:28   #4
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Re: Should I buy these solar panels?

The question of the construction quality is a bit of a personal preference thing. Ours have totally crap frames but like you suggested, you can build them up to suit your needs. Of course good aluminium pieces are going to add to the total cost but I think you are just as likely to need them to match good panels to your existing structure.

M4 connectors vary in quality, and if they have been crimped onto under spec wire you are going to end up tossing them in the bin anyway. I think that's the main problem with a pre made kit, anyway, most of the critical dimensions are going to be wrong for your needs. And the connecting cables are bound to be under rated.

Are you worried about building from scratch? Why not let us know what you need to achieve and see if CF members can point you in the direction of the best buys. I can't see where you live from your profile but if you let us know there will be more useful advice. The solar options in Oz are a lot more limited than some other countries.

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Old 09-01-2016, 08:38   #5
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Re: Should I buy these solar panels?

Hokay - good thread.

As long as soliciting advice has been offered, I ask:

I now have 3 Kyocera, ~8-10 year old (one got replaced, up to 130W due to efficiency gain at the time) 120W panels in series and a Blue Sky 60A controller.

At best, in the southern Bahamas, I sometimes will see 25A, mostly not and under 20A. But 10-15A is common as dirt. For example, at 10:30AM, at 27 latitude at nearly the worst possible angle due to season, and total overcast, I'm getting 8A.

I'm trying to figure out a way to get 2x 340W on the same available mounting space, which would split around my HF 23' antenna currently mounted/braced on the front of my mounting frame; I have a total, with that antenna, of 88" to work with in width, and if two, plenty of space forward (albeit cantilevered from my arch front).

If I could find much LONGER, but same width (or total 88"W), panels, I could go with three. One would extend to the stern and the other two forward (I wasn't thinking outside the box when I designed it, but, apparently, from my casual searching, it doesn't matter as there aren't any like that).

With efficiency WAY up from the ones I have, I can greatly increase the amount of watts available to me, at prices which probably would come in under what I paid for a single panel (~1000 at the time) for all of it/them.

However, the 340W ones I thought I'd buy is available only in pallet quantities.

If I allow for a couple of inches to miss the antenna for two, or the total width for three, what would be my best replacement for the array I have now?

Pix of my current installation, interspersed with other stuff going on at the same time, can be seen here:

Pictures: Flying Pig Early Refit + Projects/Early_Major_Alterations_Work/07-05to7-19-05
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Old 09-01-2016, 11:55   #6
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Re: Should I buy these solar panels?

I am currently looking at my first solar setup and finding huge differences in price between 'domestic' and 'marine' parts. I think some of this is a quality issue but it is also down to supply volume and competition. In some cases a panel sized for domestic installation will be half the cost per watt of one by the same company that is a 'specialist' size. Having also looked a home building panels I also fond that about half the cost of a panel is in the frame and construction so smaller panels a more per watt as they sill cost about the same to build.
looks to me like a set of PK domestic panels with a cheep Chinese charger, dont know that particular one but you could identify it fro Ebay and see if there are any reliable reviews as they range from looking good to outright con. good luck
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Old 09-01-2016, 12:03   #7
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Re: Should I buy these solar panels?

There are domestic panels which meet the description for marine - the cites are for salt, sand, and corrosive environments, individually, if not for all - but not "marine" panels.

If it's certified for a salt environment (as you'd see in coastal installations, e.g.), it should be fine for a boat.
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Old 09-01-2016, 22:47   #8
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Re: Should I buy these solar panels?

Shopping solely $ / rated W may not be the best value.

Any "standard panel" with one half of one cell shaded, will have next to zero output. If the $300 panel rated output was 300W, and the actual output was 3W, your real $/W is $100/W.

So you have 2 choices, either go with a much more expensive panel that is less susceptible to shading, or break the area up into smaller panels, so that if one half of one cell is shaded, and that panel output is zero, all other panels are at full output.

In this case, even the $ / rated W of the smaller panels is higher, the real $/W is lower.

I generally recommend ~ 100W panels. For example, if you need a 400W system, then use 4 x 100W panels. This gives some mounting flexibility 1 x 4, 2 x 2, 4 x 1, etc., so that you can use the available real estate and attempt to avoid shading as much as possible. You can bump the panel up or down slightly as needed to fit the available horizontal real estate.

Putting all your eggs in one basket, or all your production expectations in 1 panel, isn't a great idea; 2 panels is better, and 4 is better yet.

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Old 10-01-2016, 01:48   #9
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Re: Should I buy these solar panels?

Trying to get my head around this 4 panel idea. So if you have 60 cells each producing 0.5v 5a and you wire them in series you get 150w @ 30v. If yo add another set you get 300w, 2 more and you have 4 panels giving 600w @ 30v. On most boats these will be rigged in a row either across the stern on a cat or in two pairs on the bimini in a mono. Hopefully in both cases clear of boom, rigging etc. If you where to wire all 4 in parallel you would get 20a @ 30v. If one panel is shaded you still get 15a @ 30v so all is well. If you wire them in series you would then have 5a @ 120v (not a brilliant idea anyway as that could kill or cause corrosion) but also if you shade one cell does it stop any current flowing through it so you get near zero from the all panels or do you just loose 5v so you get 5a @ 115v? OK if that's the case I understand but it would be lousy way to do it anyway. Now if you have the same total of 240 cells wired in 4parallel gangs but all mounted in one frame would you not have exactly the same setup as with four separate panels? In the case of the 245w panel I was looking at this is gives 30v @ 8a presumably using 2 gangs of 60 cells each with its own diode. I am assuming this because I have never seen a 8a cell, they all seem to be around 3.8-4.3a @ 0.5v. so if they were all in series you would get 5a @ 60v (which some panels do) If that is the case I can't see why it behaves any differently to an installation using 2 120w panels each consisting of a single gang mounted next to each other? Or is this just an issue with the number of blocking diodes? I am assuming a 15v panel would have 4, a 30v panel 2 and a 60v only 1. If this is the case it is easy enough to change, just rewire from each tab column and add diodes?
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Old 10-01-2016, 22:14   #10
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Re: Should I buy these solar panels?

It would be great to get info on best output, best price, best quality, best regulator/panel/wiring/battery sokar panel installation from our CF colleagues who successfully installed, use them.
The theory concerning alternative energy in vulgarized form be great too.
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Old 10-01-2016, 22:30   #11
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Re: Should I buy these solar panels?

Roland, regarding the all in series part of your question, most semi decent panels I have met have a bypass diode so that if the panel is producing no power due to shading then at least you get power from the other panels. The better of the semi decent panels also had four or five bypass diodes in the panel itself so that you can lose part of the panel to shade without losing all. It's usually documented in even the slightly el-cheapo panels somewhere. Of course would I always trust that information...? Probably not.


Sent from my iPhone so apologies for weird autocorrect typos.
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Old 10-01-2016, 23:00   #12
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Re: Should I buy these solar panels?

I bought a couple of their 100w flexible panels last year.

So one season in only but all is ok with them. Decent build quality to look at and all measurements as per spec.

In fact better output than my older much more expensive german made fixed panels which goes to show how quickly this market is maturing.
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Old 11-01-2016, 05:07   #13
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Re: Should I buy these solar panels?

Quote:
Originally Posted by GILow View Post
Roland, regarding the all in series part of your question, most semi decent panels I have met have a bypass diode so that if the panel is producing no power due to shading then at least you get power from the other panels. The better of the semi decent panels also had four or five bypass diodes in the panel itself so that you can lose part of the panel to shade without losing all. It's usually documented in even the slightly el-cheapo panels somewhere. Of course would I always trust that information...? Probably not.


Sent from my iPhone so apologies for weird autocorrect typos.
I admit to being wrong about much of what I thought I knew (see Mark Twain for further insight).

However, when I started down this road over 10 years ago, the norm was to have isolation such that only a single row would be affected by shading of a single cell.

Is it now uncommon, since the vast bulk of panels are going to fixed locations, to have that feature? That is, is the norm now such that if a single cell is shaded (presumed meaning actually dark), the entire panel is out of service?
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Old 11-01-2016, 20:25   #14
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Re: Should I buy these solar panels?

Quote:
Originally Posted by skipgundlach View Post
I admit to being wrong about much of what I thought I knew (see Mark Twain for further insight).

However, when I started down this road over 10 years ago, the norm was to have isolation such that only a single row would be affected by shading of a single cell.

Is it now uncommon, since the vast bulk of panels are going to fixed locations, to have that feature? That is, is the norm now such that if a single cell is shaded (presumed meaning actually dark), the entire panel is out of service?
No the original position is still the norm in all the panels i looked at last year at least (even the cheapies) eg the ecoworthy ones I ended up with are 6 strings of 6 cells per panel. Block one to two cells in each string and you loose most of the current but block just one cell and you loose one string or a bit less than 1/6th of current.

I checked that out physically when i got them and thats pretty much what happens so you need to think about panel installation options and likely shading outcomes as one orientation mounting can still be way worse than another no matter how expensive the panels.
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Old 17-01-2016, 06:02   #15
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Re: Should I buy these solar panels?

I advise for flexible 1,8mms thin panels on monohulls. Framed ones are surely more economic, yet perfect only on a cat.
See:
SOLBIAN
GIOCO SOLUTIONS

As a second cost-divide, do consider mono-crystalline panels, way more efficient.

As a third one, in priority, an MPPT, if power installed exceeds 5/600W
Do not ever save on wires (double the ones packaged, if any) and install charger 6ft afar from batteries max., with a T sensor.

It helps, chasing for the sun :-)
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