I've been using my 6000XP for about a week now. I have 3200W of panels connected to a single string, and I have Tigo TS4-A-Os connected to deal with some hard shadows.
Whether I'm using the optimizers or not, I've found the voltage will just sporadically plummet from hundreds or even thousands of watts to just 56-66W. Last week, it did the same except it would drop to around 140-160W. Sometimes this would be due to an obvious shadow, though I find it confusing why the bypass diode wouldn't kick in (hence me buying the Tigos, in the event local PPT can improve the results). Sometimes there is no change in shadow or brightness.
Whenever this happens, the voltage is typically between 280-300v, which for my configuration implies it's open-circuit. Even in situations where half of my 8 panels are completely shaded, they should produce over 120v.
Whether I put the string on MPPT 1 or 2, the behavior is identical. With a multimeter, I tested every panel's bypass diode and only one panel has a slight discrepancy, but it's still within normal range. When I'm generating some meaningful power (even if just 300W) I also checked the amperage for both sets of wires connected to the Tigos, and it's pretty consistent across the board.
All this leads me to believe there's something glitching out about the inverter's firmware or MPPT algorithm.
