question

@Fenix, I've seen similar occurrences in several cases and in each case, the cause was a defective connection (or a defective breaker/fuse) somewhere in the chain. I would start at your panels and work your way back to the controller, testing each connection to make sure that you have good crimps, tight connectors, the wire is good, and any breakers/fuses are name-brand and appropriately rated, then (if all that checks out) work your way from the controller to the battery following the same procedure.

Looking at the graph, the drop-out of current combined with the spike in voltage indicates that the controller stopped applying load to the PV input for a period of time; the typical reason for doing this (in my experience) is a loose connection, bad crimp, or knockoff breaker or other component on the PV side that's overheating, causing the controller to throttle itself to avoid damage to the system. It's equally possible that the defect is on the battery side, however, as the effect will be the same when the controller throttles itself.

Bottom line: start at one end and work your way to the other checking for any loose connections, bad crimps (you should be able to apply at least 50lbs of pull to a crimp without it moving) or components that may be overheating. Remember that anything short of a solid connection is going to generate heat, so if you have a handheld IR thermometer or FLIR attachment for your phone, those will be invaluable tools in troubleshooting.

I will do that

Tks you so much