I initially thought this might go for
the troubleshoot and fix and electrical appliance BB. While I did need to troubleshoot the issue with my off-grid photovoltaic system in the end I'm not really fixing an electrical appliance. Instead I am replacing it, and sending the old faulty one back to the manufacture for repair. It will become a back up unit for me should future issues arise. So that makes the electricity oddball category seem like the best spot to me. Please let me know if there is a better spot.
So anyway, my solar system happens to have two separate solar arrays for reasons that annoy me which I won't get into. As it turns out this provided resilience that saved my bacon, or at least kept me from going without power. The two different arrays each have their own charge controller. One morning while clearing snow off the panels I saw that one of the arrays wasn't generating any power while the other was putting out several hundred watts. They are never the exact same, but no power and hundreds of watts was a clear indication of an issue needing attention! I worried that perhaps a panel had gone bad. Then I noticed the charge controller for the bad array was registering voltage, just no amps or watts. Investigating further it seems the voltage it showed was consistent with the open circuit voltage (VOC) for the panels in that array. This told me the panels themselves were fine there was just no load on them when there should be. That strongly suggested the charge controller for that array being the issue since everything else in the system was functioning. Thankfully I did have the second array to power everything. Thankfully too the sun finally began making more regular appearances just at that time. Only a week before and the one array would not have been sufficient.
The trouble shooting guide for the charge controller did list my issue and recommended if I had it to call the manufacturer. I peeked in at the internal guts of the unit but didn't see any obvious thing I could identify as bad and fixable by me with my skill set. Knowing the manufacturer would not be quick even if they were right on top of things I decided to order a new replacement so I could get my system fully functional before the weather changed and became cloudy again. (Quite possible this time of year where I am!)
I thought this would be a simple swap out. Ha! So I have now learned there are locking nuts for conduit pipe fittings. They work really really really good at locking in place and never backing out! It would just dig into the softish aluminum of the case and not turn any more. In the end, after a bit of swearing and stopping to take deep relaxing breaths, I found I had to break the nut to remove it. Due to it's tight location this was best done with a drill. (I swear it acted like hardened steel too when trying to drill!) Eventually I got through it, breaking it open, then bending and twisting it enough to remove. After that it was a fairly straightforward job.
I made sure to take reference photos of where all the wires were and how the various jumper setting were set. That allowed me to easily hook up the new unit as the old one was. Once powered up I did also need to go in and program all the various settings to match what they were and get it linked in its "follow me" mode with the second charge controller.
All is happy again in my homestead photovoltaic land. The defective unit will be shipping out tomorrow for eventual repair. Then it will be stored away to be on hand and ready the next time a unit fails.
All told I spent over 3.5 hours on this job, which is a silly amount of time. Part of that was the need to run to the hardware store for a new locking nut since I had to destroy the old one to remove it. I don't know if a professional would have an easy way to remove it. I think they still would have had to break it somehow to get it off, but they would have known that rather quickly. My guess is that a pro could have been done in 30 to 45 minutes.