Three sections of paneling on the roof of my RV. All three are two 250 watt and one 100 watt panels installed in series. They are running to 3 plug T with each run going to a bus to feed three separate MPPTs. I have two Victron MPPT 100/50 and one MPPT 100/30.
Assuming 12V system.
So, you have three separate arrays:
Array 1: 250W + 250W + 100W to MPPT 100/50
Array 2: 250W + 250W + 100W to MPPT 100/50
Array 3: 250W + 250W + 100W to MPPT 100/30
If so, I see four issues:
First, depending on the 250W panel type, there's a good chance you're hitting your 100Voc max on each MPPT, especially if it's colder than 77°F/25°C
Second, any partial shading on any of the 3 panels in the string can cause performance problems.
Third, of you are splitting panels between multiple MPPT, that's going to produce erratic performance and power loss as the MPPTs will fight each other. Each string must be connected to only one MPPT.
Fourth, you are almost certainly crippling your 250W panels' performance by having them in series with the 100W panel. Your 100W panel likely has a Vmp around 5-6A. This panel will force your 250W panels to run at the same current.
When mixing panels, those in series need to have nearly identical Imp/Isc ratings. The series panels will be limited to the LOWEST Imp in the string. Those in parallel should have very similar Vmp.
Lastly, while it might be complicated, it would be far more optimal to connect 3S (or 3P depending on Voc) 250W to each 100/50MPPT and 3S 100W to the 100/30MPPT. Additionally, if you're on a 12V system it might be more advantageous to parallel them rather than serial to ensure they are more shading tolerant.
