For any system I've connected, I color code everything. Even when I used black in color positive wiring, I always add a inch or two of red tape at the terminous to document to the uninformed that these are positive wires.
I recently had to help a neighbor decommission his old solar system that had totally trashed his batteries because of a faulty controller. It was a total mismatch of any color wiring he had on hand at the moment. It was a nightmare.
I see though that you actually used a red wire for your positive buss, leading to the controller. What's the gauge? It appears to be a little light for carrying the combined amperage of all your strings.
All in all, it looks like a neat and tidy install, with good workmanship.