100 watt shade tolerant flexible solar panel: test 1 

Interesting stuff, I’ll look into Shade Stopper as I get considerable shading on my off grid arrays.

Wild. A bypass Diode. Makes perfect sense.

Very interesting data, although there are a lot of possible explanations for the variation in output between the ShadeStopper & Renogy panels, which is only 9% overall in favor of the ShadeStopper. As you noted, the behavior of the MPPT controllers could have some effect. The fact that they are both rated at 100W doesn't mean their actual output would be the same under any given condition, and some manufacturers tend to be more conservative in their ratings than others. And I don't know about the ShadeStopper panels, but some flexible panels have a "pebbly" surface that they claim allows for more light collection at off-angles. It appears there may be slight variations in the angles/direction in your setup, and they're certainly not going to be pointing in the perfectly optimal direction most of the time in any event. Still, it's a significant difference overall. Will be interesting to see how well the bypass diode arrangement works.