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 yield for a 100w panel:
[caption id=”” align=”alignnone” width=”295”] should be “lux” not “lumens”[/caption]
That lines up pretty closely with my observations.