1) Is there any benefit to seasonal adjustment's? If yes, how much.
2) For 2 sets of series panels in parallel, if one string is shaded, does it affect the output of the unshaded string?
You can visit RReDC to compare data for a location in your area. For example, you might to compare the annual total of monthly averages for a south-facing array tilted up at latitude vs the totals for April through September for Lat + 15 degrees and October through March for Lat - 15 degrees. I think the difference for fixed at latitude vs summer- and winter settings in my area is <4%.
"I live in Jamaica..."