My solar panels have suddenly died.

[Privilege]

I have four 100w solar panels wired in series with the 4th panel going off to the charge controller. I'm getting no voltage going to the controller.
Looking under the panels, I see that the plastic cover over the diodes and stuff on the 2nd panel has fallen off and the interior is badly coroded. I know that a failure of the 2nd panel would affect the 1st one, but would it also affect the downstream panels too?

I'm trying to work out what might be wrong before removing and testing the entire array.

[Captain Bill]

Originally Posted by Privilege

I have four 100w solar panels wired in series with the 4th panel going off to the charge controller. I'm getting no voltage going to the controller.
Looking under the panels, I see that the plastic cover over the diodes and stuff on the 2nd panel has fallen off and the interior is badly coroded. I know that a failure of the 2nd panel would affect the 1st one, but would it also affect the downstream panels too?

I'm trying to work out what might be wrong before removing and testing the entire array.

In a series string the failure of one panel will take out the entire array if the system was not installed with bypass diodes. Even if it was, the usual place to find those bypass diodes is in the connector box which you have described. If the observed corrosion is the source of your problem (very likely) then the bypass diode is as likely to have failed as the panel wiring. If the bypass diode fails and the panel fails you loose the whole array. This is one of the problems with series based arrays.

[Privilege]

Thank you kind sir.

[CatNewBee]

You can just re-wire your Array by bypassing the failed panel and have it working again (or just short-cut the wires in in the Box of the failed panel, it should work too).

Your MPPT Controller should be able to deal with the lower voltage and you will have the system running again by losing only 25% on Power (300Wp instead of 400Wp).

Eventually you can then replace the dead panel and rewire back to normal.

[zeehag]

simply put:


oh goody. your panels have failed. send them to me, free of charge, so i can rewire them for success.....
before removing panels from position, i would start with checking connections, your primary fail point.
oh but i sooo love the folks who actually believe it is their panels.. helps my array increase.
connections first, panels can live decades until connections fail, then start over. oops .... did i say that out loud?? ohmy . now how am i gonna get free "dead" panels????
damn
oh yeah and sometimes wires crack. that not good. makes panels act dead despite seemingly perfect connection points. hahahahahahaha



one question for the folks out there--- when your solar panel wire insulation cracks from sun exposure, is nail polish good for that repair??? tape would only allow more water ingress with the rains here.
i am serious, folks....best answer fast as it is due to pour on us any second.....

[Hunky Dory]

You may have problems as suggested by others. I have a 200 watt panel that is new, it worked great last fall, During the winter it stopped working??? After reading up I found that if the battery voltage drops below a certain voltage the unit stops producing. I plugged my charger in, brought the voltage up and now everything works again. May be this simple.

[guyrj33]

I'd use liquid rubber or 'whip-it' dressing, or even silicone before nail polish to fill a void in the wire insulation.

[CruiseEasy]

Self fusing tape would do fine and no drying time required. Most hardware stores carry it and properly applied, it is 100% waterproof.

[zeehag]

i wish there were the options of liquid rubber and whipit etc here.. not inside usa, options are limited. nailpolish is available. it is a second hand unit with the wires from unit to connector that have failing points....so it cant hurt. these have longevity written currently in months.. semi rigids with near opaque outer casing. i got em free, last fall or summer, so i got my moneys worth of em, and i have 2 remaining. po got new and i received the donation willingly, as usual, for research.
i loved liquid rubber, it made excellent repairs. i have yet to see something similar here--i know it must exist.
aaaahhh sillycomb..mexicos best repair tool
as for low battery voltage--yes makes a huge difference.l the regulator will not allow any passing of the current to battery. i have one panel straight into batteries.. i prevent sun from seeing this one until any reduction in battery voltage occurs. btdt 2 times now.

[Nani Kai]

Originally Posted by zeehag

simply put:
one question for the folks out there--- when your solar panel wire insulation cracks from sun exposure, is nail polish good for that repair??? tape would only allow more water ingress with the rains here.
i am serious, folks....best answer fast as it is due to pour on us any second.....

I can't confirm that nail polish would well work on wires (I think the greatest concern would be it getting brittle over time, cracking and allowing water ingress) but I can attest to it's overall waterproofing abilities. In the well spent years of my youth we drift dived in deep water hunting big game fish with spear guns. Because of the rare encounter with large, aggressive, determined sharks (most encounters ended harmoniously) we carried bang sticks which were basically zip guns attached to pole spears. To water proof the ammo (standard issue .308 or .44 magnum) we coated the pressed fitting between bullet and brass casing with several coats of clear fingernail polish. Worked extremely well to depths exceeding 200' and lasted indefinitely.

[hellosailor]

zeehag-
You can make your own sealant, even in the boondocks, even if it isn't liquid rubber or vinyl. You can use many things, from fingernail polish to canning wax or beeswax (I know, it tends to run in the heat) or you can dice up some plastic in a high end solvent, let it dissolve thoroughly for a day or two, and then you've really got "the real" liquid vinyl to paint over things. Someone must have xylene or other aggressive solvents in their paint locker that you can experiment with.

Privilege-
If one connection box is all corroded and has failed, you must assume the other boxes may ALL have similar internal problems. It should be a priority to open them all up and make sure they are cleaned out and resealed. That's easier to do if you either take the panels down or invert the boat (G) so you can work on them without stuff falling into your eyes, or overboard. Plain vinegar and a toothbrush often are all you need to clean off green gunk, and if you've got nothing better, then use plain grease to coat everything when it is clean and reassembled. That will at least discourage more corrosion.
If you have any doubts about putting it all together again, take cell phone pix as you go and you'll have something to refer back to.

[zeehag]

supercoated it all in sillycomb.....found multiple places on one wire for a good fail
only want these for this season, or until i am done repairing, mebbe 3 yrs max, hahahahaa
luckily my potential fails are outside the connection box, so surgery is still possible.

[Rorzech]

Maybe that panel isn't pooched . Take the cover and get your Dremel in there with a little wire brush and a sanding disk and clean out all the corrosion (while the panel is covered) and test all the connections with a volt meter for your open circuit voltage (with it uncovered)after all the connections are back together, brush on some liquid electrical tape real good , make sure the sealing O-ring is nicely back on the edge of the cover and calk every where you think moisture me have entered. Then carefully check the other boxes for the same corrosion. Take a picture before you pull all the wires off and even label them to make re-assembly easy. Good quality crimp-on connectors with good eyelets will help greatly. Take your time and don't get yourself shocked. DC is more dangerous than AC.

[masonc]

Test each panel by shorting it and measuring the short circuit current (Isc) with a Dc clamp meter. That way you will know that each one works or doesn't.

[CatNewBee]

Originally Posted by masonc

Test each panel by shorting it and measuring the short circuit current (Isc) with a Dc clamp meter. That way you will know that each one works or doesn't.

That makes sense. I have on my RV 5 Flex-Panels on the roof for 5 years now. 2 of them failed in the mean time, one was totally broken - no Isc / Voc measurable - the fail is inside the panel - I removed the bypass diodes and measured on the connection bars directly with a multi-meter, the second was half dead, one side produces power and the second does not, so the bypass diode delivers half of the Wattage / Voltage.

Panels can fail, especially the flexible ones. So a multi-meter is your friend and also consider not only the panel itself but also the bypass diodes and the optional de-coupling diodes in case of parallel connections.