Solar panel stopped delivering charger and voltage drops to 13v as soon as connected

[LifesBetterWhenYoureBeating]

One of my solar panels recently stopped charging my batteries. I noticed on my mppt that it wasn't delivering any current and the voltage would stay at around 13v (same as the battery) the whole day. When I measure OCV I get the 22v expected, and the same for short circuit current, but as soon as I connect it to the mppt the voltage drops and no current is delivered. Sometimes there is a short voltage spike and it delivers a tiny amount of current (0.1-0.3A) for a few seconds but then the voltage drops again

To make things more interesting, some days it comes back to life and delivers current the whole day.

Is this a common failure mode in solar panels, or is there anything I should look into my setup?

Thanks in advance!

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[Franziska]

Check all contacts and switches for corrosion and tightness.
We had a panel which seemed to give intermittent and various power. The panel seemed fine but nothing arrived.

We found is was a burnt through high amp switch which was not performing up to it's specification.

[SailingHarmonie]

Solar cells do not fail in this way. It is a connection issue--somewhere. MIGHT be inside the panel, but unlikely.

Where the most likely place really depends on the quality and attention to detail on the installation.

[Kastaway]

Faulty mppt maybe?

[Uncle Bob]

If your panels have mc4 connectors I would check these first then every other connection in the string.

[more]

Originally Posted by LifesBetterWhenYoureBeating

.

Is this a common failure mode in solar panels, or is there anything I should look into my setup?

Thanks in advance!
]

yes this is comone.
what to do

1/check and clean connection in the string.
2/find what solar is faulty in string
3/if connection is good ,solar panel have faulty bypass diode in connection box

checking solar panel is easy test with this special solar tester

https://www.aliexpress.com/item/1005...Zex#nav-review