Check this mess out

[DontUredRing]

Bought this over a year ago and something told me to teat it but I though "nahhh, I don't need to use it yet". It's one of those generic Coleman 18w panel kits that comes in a 7A charge controller from tractor supply. I decided I was going to pair it up with a few more panels I have, just for one of my campers in the woods at the back of my place. No power from it and so I started digging in. The 1st pic is what I saw when I opened the junction box. Definitely wrong. I'm guessing that whoever wired it, was about to quit. Hopefully they did. The 2nd pic is my interpretation of how it was supposed to be good. It's got a 1N4007 diode in there and I've got the anode aimed towards the positive from the panel. And I also wanted to make sure that the bare prong on the connector was indeed negative. Red wire, but negative nonetheless. The rest of the pics are of my testing, and as you can see, that's jacked up like a soup sandwich. No output originally, fixed the wiring in the junction box, diode is still good, and now I only get output with the negative probe in the bare pros on the connector, and holding the positive probe in my hand and then touching the aluminum side of the panel with my hand. Note that the positive probe directly to the aluminum gives me nothing, but holding the probe in my hand and then touching the aluminum gives me about 16v-18v. Also, touching the positive probe without touching the panel at all, gives me up to 8v. I'm pretty electric but not like that.

The panel has never been used, purchased new and was kept in a dry place where it could not have been damaged. I was thinking that the panel is shorted out and have contemplated just trashing it, as it's too late to return it. The charge controller that came with it is good, but is not fused, so I will be adding a fuse to it. It works great, as long as im touching the aluminum with my bare hand and I may just have the kids go hold onto the panel when I want to charge a battery, instead of grounding them because im all about productivity. Anyways, I thought you guys would get a kick out of that.

 

[rodrick]

I think you should double check the wiring diagram you basically eliminated the diode

 

[crossy]

Your readings to the metalwork are possibly a small pink fish. Your meter will have a massive input impedance and any leakage will show up as a reading. For peace of mind check resistance between the metalwork and each panel terminal (panel face down so there's no voltage to confuse the meter).

Ignoring the diode for now do you get an output voltage directly on the panel connections (the outer two of the three terminals)? Note which is +ve.

I suspect the diode is supposed to be a backflow preventer in which case the stripey end (cathode) should point towards the negative panel terminal. Like picture 1255 if the right-hand terminal is in fact the panel -ve.

Once it's confirmed OK you should get voltage at the other end of the cable. Have you confirmed the cable continuity is good?

 

[DontUredRing]

Ok, the black wire is/was connected to the PV+ and the red wire is/was connected to PV-. I don't think it was wired correctly in the junction box when I first purchased it. With or without the diode, the result is the same. Probing the terminals in the back of the panel does absolutely nothing, with or without the diode. The 1255 photo is how it was wired from the factory, which makes no sense. Removed all wires and the diode, except for the silver strips that connect the panel to the terminals, with the same issue. Cable continuity is good. The only way to get any output from the panel is to probe the PV- with my DVM, hold the positive probe of my DVM between my fingers and then touch the aluminum housing of the panel itself. Then, I block the light coming to the panel, and the voltage indeed plummets. All of this is without any load. Also, touching the positive probe of my DVM directly to the aluminum, shows no output. My idea was that there must be an internal short somewhere because I scratched the oxide layer off of the aluminum and it made no difference. I'm guessing that the center terminal would be a neutral as the anode side of the diode was connected to it. The diode in 1255 had the cathode towards PV+, which is the black wire, from the factory. The 3310 photo is how I have wired it, as that seemed to make the most sense, but the diode would then be backwards. I haven't tried connecting the cathode end of the diode directly to PV-, but I do know that there is no continuity between PV+ (red wire) OR PV- (black wire) to the center terminal. My reasoning behind 1255 being wrong was because the diode appears to be backwards and PV+ was not connected to anything past the junction block. It was just $100 or so, and I'm not too worried about it, but I do like puzzles and haven't come across many things that I couldn't fix.

 

[DontUredRing]

So I went out and purchased another identical panel and checked its wiring and it works as it should. I'm thinking there is some internal short somewhere and that's not something I can fix. So I'm going to trash the old one but keep the diode, wires and charge controller. 2938 is the correct wiring as compared to the new one, so it must have just been a dud that was wired incorrectly from the factory. 1255 is how it was originally wired. I suppose that there's the possibility that someone purchased it, messed with it and returned it, but these are super simple. If that's the case, they did a very good job of repacking everything. Maybe they had one, ruined it quickly, then bought another one and returned the ruined one. People do that. Sunforce makes these and Coleman branded them. No biggie, but I'll check these from now on!