Half amperage from semi flexible solar panel? Possibly damaged?

[redpointist]

I have 3 of the 100w semi flexible Renogy solar panels, and while I was hooking them up to test them out, a gust of wind came and knocked them off the bimini onto the cockpit seat before I could get them secured. It wasn't a big drop and the wire caught on the bimini and lessened the blow a bit, but upon testing the output, two of the panels are putting out about 5A and one is putting out 2.5A.

I took the suspect panel home with me for some more testing, and when i hook the panel directly to the car battery in full sun (in Tennessee) its putting out 2.5A at about 19V. If I short out the two wires momentarily the amperage jumps to 5.3 amps. The short circuit voltage on the panel says its 6.1A and the open circuit voltage says its 21.7V so 5.3A and 19V seems like itd be about right for the Tennessee sun hitting the panel.

My question is why is the panel only putting out half the amperage as the other two into the battery, despite it being able to produce the full amperage when shorted?

[exMaggieDrum]

I haven't looked at the flexible panels but my first instinct would be to suspect the wires going in to the panel. When they were blown in to the cockpit they may have been subject to a pull shock load. I would contact the manufacturer and ask them if you can. But if you did a head-to-head comparison from the two others and this one then it certainly has an issue. But there is also the possibility of a manufacturing defect.

[Paul Elliott]

Many of the panels have two strings of solar cells, each string being connected in parallel. If one of the cells gets cracked, of an internal connection is broken, then that cell's string will put out zero amps. The second string will continue to function, thus the panel delivers half the nominal output.

[newhaul]

Call manufacturer just don't mention the drop to them just that its not working right. They should replace it on warranty

[sailm8]

Another poster used these brand panels and used Amazon prime so he could return them free if they were not performing up to specs. He had to return about half of them in order to get a matched set.

[Maine Sail]

Originally Posted by sailm8

Another poster used these brand panels and used Amazon prime so he could return them free if they were not performing up to specs. He had to return about half of them in order to get a matched set.

Bingo! The QC on these Chinese copy-cat panels is pretty abhorrent. Always test them and send them back when they don't perform!!

[colemj]

Originally Posted by Maine Sail

Bingo! The QC on these Chinese copy-cat panels is pretty abhorrent. Always test them and send them back when they don't perform!!

We just bought two of the Renogy hard panels and they are performing above their specs. I didn't know they were Chinese "copy-cat" panels. I guess we got lucky with ours?

BTW, the OP did state possible damage on his end, so one can't jump to a QC conclusion from that.

Mark

[capn_billl]

It may have been a cold solder joint.


A simple tug on the wire shouldn't have pulled them loose.

[Maine Sail]

Originally Posted by colemj

We just bought two of the Renogy hard panels and they are performing above their specs. I didn't know they were Chinese "copy-cat" panels. I guess we got lucky with ours?

BTW, the OP did state possible damage on his end, so one can't jump to a QC conclusion from that.

Mark

The OP was referencing the Renogy "semi-flexible" panels.

Originally Posted by redpointist

I have 3 of the 100w semi flexible Renogy solar panels

In my experience I find these are rather marginal quality knock offs of the Italian made Solbian panels. I have seen numerous panels come out of the the same Chinese factory with a Renogy, Shine, Grape etc. label on them not meeting spec, right out of the box. It was not "jump to conclusions" because I have seen, tested and measured this on numerous occasions, just as others have, and these have not been dropped..

I was merely stating what I and others have experienced with these panels and to beware of the often abhorrent QC on them..

The problem is they don't use A grade cells and they can be riddled with microcracking. If you get panels meeting spec they can actually be a good value, but if you don't test them, then you have no way to know so you can send them back and try another...

I recommend testing any of the Chinese semi-flexible panels against spec, as best you can, and against each other to ensure they are not under performing.

[Paul Mazza]

The Chinese knock off comment has me wondering. I have a number of the 100 and 50 watt Renogy semi flexible panels and they say made in Thailand. So that would make them Thai knock offs of the Italian panels.

[colemj]

Originally Posted by Maine Sail

The OP was referencing the Renogy "semi-flexible" panels.

I assume our hard ones are also Chinese knockoffs?

Either way, they are performing above specs and were inexpensive.

Mark