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Cheap used solar panels on ebay... $40/panel
#1
Just wanted to share... happened to come across it while browsing... seems like a good deal.... used... has snail trails so definitely some power loss... I have 12 panels like that and they still put out 85%+. I bought mine used locally 3 years back and I don't see any major decline in output because of them. For $40/panel is kinda decent. 

https://www.ebay.com/itm/Used-250W-60-Ce...2614945473
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#2
"Mfg labels have been removed"
hm.... what possibly could be the reason to put in the time and effort to remove those labels, I wonder.
Modular PowerShelf using 3D printed packs.  60kWh and growing.
https://secondlifestorage.com/showthread.php?tid=6458
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#3
Might be in order to resell them ( most I think come from commercial solar farms) they are required to remove them per an agreement between the farm and the solar panel maker?

Later floyd
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#4
Even the solar panel recycler that is in Miami Fl (very big company) does that. Sometimes they just peel off the manufacturers name, but leave the stats page intact.
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#5
Snail trails can develop into heating spots & even cause fires if used at "full power".
I'd give them a miss unless you only need maybe 20% of the approx original rated power for a small project
(compare panel size to guess original specs?)
Running off solar, DIY & electronics fan :-)
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#6
(05-09-2020, 08:52 AM)Redpacket Wrote: Snail trails can develop into heating spots & even cause fires if used at "full power".
I'd give them a miss unless you only need maybe 20% of the approx original rated power for a small project
(compare panel size to guess original specs?)

I'll post up some pics of my panels later but I've yet to see such losses on my panels. They do look like severed connections there and I do see some power loss. I guess if it's bad enough the bypass diodes would trigger and move to the next section. My panels are wired in 3 separate banks with 3 bypass diodes in it. I think that's a common setup on most panels. So if a particular cell has a really bad snail trail I suppose that would reduce the output of that panel by a third since it will bypass that section

I have 9 panels hooked to my PIP that are 245W and at this time of the year should be my optimal angle I am getting around 1800W at noon. That's about 81% of the rated output.



I'm curious if anyone actually has suffered down to 20% because of snail trails. Actually I'd love to hear what peak output you guys get vs rated output?
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#7
Glad you're getting some good W out of yours, I was meaning using them were you don't need the full output, eg charging a 2nd use like a fence energizer, gate opener or maybe garden lights? Ie so as not to make hotspots at the cracks (snail trails are cracked silicon wafers right?)
2nd hand panels from a system upgrade might be better than ones removed with snail trails or other defects...?
Running off solar, DIY & electronics fan :-)
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#8
(05-09-2020, 02:35 PM)Redpacket Wrote: Glad you're getting some good W out of yours, I was meaning using them were you don't need the full output, eg charging a 2nd use like a fence energizer, gate opener or maybe garden lights? Ie so as not to make hotspots at the cracks (snail trails are cracked silicon wafers right?)
2nd hand panels from a system upgrade might be better than ones removed with snail trails or other defects...?

So are you saying that if we should not ever run at full power the panels otherwise it will catch on fire? I'm curious as I've been running them for 3 years now so should I be worried? Has there been safety recalls because of this?
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#9
https://blog.greendealflow.com/the-five-...lar-panels Wrote:1) Hot spots

Hot spots are places on the panels which are overloaded and therefore become warm. Hotspots on panels are mainly caused by badly-soldered connections, or are a result of a structural defect in the solar cells.

Badly-soldered connections cause low resistance in the part of the panel that receives the power generated by the cell. As a result, the voltage can rise, which leads to a hotspot in the soldered points and/or a cell. This phenomenon can ultimately lead to a short-circuit, and reduces the performance and lifespan of the PV panel. We have identified hot spots in several solar parks, leading to solar panels being replaced, adding significant Opex costs to those projects.

4) Snail trail contamination

Snail trail is a discolouration of the panel which usually only manifests itself after a couple of years of production. Snail trails have multiple causes, but one cause can be attributed to the use of defective front metallization silver paste, in the solar cell manufacturing process. Defective silver paste can lead to moisture in the panel, and as a result of this moisture, an oxydation can occur between the silver paste and the encapsulation material called EVA (ethylene vinyl acetate).

This unwanted process releases silver oxide, acetic acid (vinegar) and hydrogen. The effect of this reaction is fed from the back of the panel to the front of the panel, and causes a chemical breakdown on the front of the panel. This becomes visible as ‘snail trails’, resulting in a reduction in the panel’s performance. The snail trails can also arise as a result of microscopic cracks in the panel.
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#10
I found some of the info I remembered reading, please see these threads:
Note the "hippiesparx" guy is one of the most respected solar installers in Australia
https://forums.whirlpool.net.au/archive/2545691
and this one:
https://forums.whirlpool.net.au/thread/91kr66j9?p=9 (long read sorry, but really good discussion on "snail trails")

Bottom line seems to be it can vary a lot from harmless cosmetic to fire causing.
There must be a reason the panels are being sold cheap & if there's any signs of heating, I would not use them.
Running off solar, DIY & electronics fan :-)
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