I guess that 28Voc limit didn't matter if it was in a network or whatever it was really designed for. Not RVs that's for sure. Seems silly otherwise, no idea.
Roy you can't mix 24s and 12s with the same controller unless you series the 12s as a 24 and then combine the 24s.
I have a 230w 24 that needs MPPT and a 130w 12 that does not but would work with MPPT, but I can't put them on the one MPPT controller because I can't make them both 24s or both 12s. If I had two 65s instead of the 130 I could series them as a 24v 130 and run that with the 230.
What I do is have a $13 PWM controller for the 130 and put it on the same battery bank as the controller for the 230 so I still get total amps to the battery. It gets awkward having both 12s and 24s.
You get more choice if you have two 12s instead of one big 24. Two 100w can be in series as a 24 with MPPT or in parallel as a 12 with PWM. With a single 200 you get no choice, it needs a 24v MPPT controller.