solar yield in overcast conditions

Over the past few years I’d estimated that my system puts out about 25-33% of normal max in bright overcast 20% in overcast 10% in dark overcast It was guesswork, but then I saw this article that gave lux for various sky conditions. I plugged the values into a spreadsheet to convert the lux into theoretical max

Mythtesting: higher voltage for additional yield in the mornings

I am a fan of higher-voltage panels, serial panel configs,etc for several reasons.   But I think there are some hyperbolic claims about their ability to collect extra power in the dawn/dusk shoulders. The theory (and actuality), illustrated with 2x 100w 12v panels is that  solar panel voltage stabilizes above ~20% insolation;  below that it falls