For any and all people of the future who stumble upon this thread with a similar problem: it turned out to be a faulty charge controller. I put in a warranty request, sent the unit back to the distributor, and they tested it and found it to be faulty. The sent me a replacement MPPT that works...
This is a strange one for you all. My basic project is that I have an already existing and functional home-made UPS and I thought it would be cool to add a solar charge controller to it for some additional capability.
I'm honestly not even sure which part of my setup is the source of my...
It's a good thought, but indeed I did try exactly that, and saw the same behavior on different days in different weather conditions. I didn't get screenshots but I repeated this test a couple of weeks ago in full sunlight. I was hoping it wasn't a faulty Victron unit but I can't imagine what...