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Surviver76

yuma az

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Posted: 07/12/18 03:51pm Link  |  Quote  |  Print  |  Notify Moderator

I am full time and met another full-timer who has a solar Panel issue.
He is in an older C-Class Ford and picked up a panel and got it twisted. Apparently, he reversed the polarity and tried to hook into his controller and of course something blew.
I built my own solar system so offered to lend a hand in sorting things out. The panel is off the roof and so I metered the pigtails while the sun was on the panel and got a one. No good signal. So then I dug the insulation out of the junction box on the back of the panel and again let the sun on it, got underneath and metered the terminals and still got a one on my meter.
My question is this. In a case such as this, is it possible for the cells to get somehow ruptured to where the panel is ruined? I never thought so but with no signal, I wonder. Then I thought well looks like some diodes or something in that junction box. If they were fried, could that cause the panel to show no signal when the terminals are metered directly? Any help appreciated.

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2oldman

Burley ID

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Posted: 07/12/18 04:22pm Link  |  Quote  |  Print  |  Notify Moderator

I think I'd cut the wires to that horrible-looking jct box and measure again.

Surviver76

yuma az

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Posted: 07/12/18 04:43pm Link  |  Quote  |  Print  |  Notify Moderator

Ok thanks. Horrible looking eh?
Do you mean horrible cheap crappy junction box brand
or horrible mess which it obviously is?
We wanted to get to the terminals to meter them directly as
I indicated.

One thing: If we cut the feeds to say 18" out as you suggest and meter them,
wouldn't metering the actual terminals within the box be better, more direct?


If this were your panel doing this,
what would you do? Thanks again.... M

Surviver76

yuma az

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Posted: 07/12/18 04:46pm Link  |  Quote  |  Print  |  Notify Moderator

So my question again is, is it physically possible to fry a panel, the whole panel, each and every cell?

time2roll

Southern California

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Posted: 07/12/18 05:10pm Link  |  Quote  |  Print  |  Notify Moderator

Did he drop, bend or twist the panel? Yes it is possible to physically damage the panel.

The diodes are bypass diodes in case any of the three sections are shaded or in your case damaged. The bypass diodes allow current from the functioning sections to bypass the others. I doubt there is an issue with the diodes.

Generally you can short the panel leads and no harm will come to the panel itself. Controller is polarity critical and is easily damaged with reverse polarity.

I assume you verified the meter was working. Generally I would look at getting a new panel if you can't find 40 volts.

325 watt panel $166


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Tom_M

New Hope, MN

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Posted: 07/12/18 05:39pm Link  |  Quote  |  Print  |  Notify Moderator

Surviver76 wrote:

I metered the pigtails while the sun was on the panel and got a one.
One what? 1 volt? Is your meter on the correct range? The panel is capable of putting out near 50 volts. If the meter is on 20 volt range, you are overloading the meter.


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MrWizard

Traveling

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Posted: 07/12/18 07:02pm Link  |  Quote  |  Print  |  Notify Moderator

can you fry a panel ?

yes hook it to 110vac

hook the panel in series with the alternator charge line to the battery
only 14v but 100amps ?

hook it directly to the battery backwards ? IDK maybe


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Surviver76

yuma az

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Posted: 07/12/18 07:06pm Link  |  Quote  |  Print  |  Notify Moderator

Time2Roll, Yes, I immediately took the meter as set to my rig and got 14 volts on the batt terminals of my controller.
No, he did not physically bump or drop the panel.
So I had believed as you say that a reverse of polarity could not fry the panel itself. Seems odd to me, metering the terminals in the junction box with full sun on the panel should be the ultimate test of the panels output right? Direct metering...

coolmom42

Middle Tennessee

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Posted: 07/12/18 07:15pm Link  |  Quote  |  Print  |  Notify Moderator

Surviver76 wrote:

Time2Roll, Yes, I immediately took the meter as set to my rig and got 14 volts on the batt terminals of my controller.
No, he did not physically bump or drop the panel.
So I had believed as you say that a reverse of polarity could not fry the panel itself. Seems odd to me, metering the terminals in the junction box with full sun on the panel should be the ultimate test of the panels output right? Direct metering...


You could get 14 V on your meter and still not have it set to a large enough range to read the voltage off the solar panels. I don't know what the ranges are on your meter but generally it's multiples of 10 so set yours at 100 or higher.


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2oldman

Burley ID

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Posted: 07/12/18 07:36pm Link  |  Quote  |  Print  |  Notify Moderator

Surviver76 wrote:

If this were your panel doing this,what would you do?
The jct box looks like somebody tossed acid in it. I would clip the wires just like I said and see if the panel is ok. You can get by sans junction box.

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