With parallel strings, when one panel is shaded it pulls that panel's voltage down a bit, which seems to pull the whole other string's voltage down (because the total voltage for the whole string must be the same for A and B). See the photo... the max output of a panel in this array seems to peak at about 240 or 250 watts. In string C, which is not parallel, the peak is 300+ watts.
Is this caused by a bad MPPT algorithm? It appears that Tigo optimization doesn't help me here as much as I'd hoped it might...
Anyone have any ideas of things to test out?