When I got my solar panels
, some years back, (11 and 14 years ago), I went with mono crystalline, because of available deck
space. The top of the line mono panels, were more expensive, but WAY smaller for the same wattage, than ANY multi crystalline panels! I have not researched them lately, however. Look up the specs and see if it is still true...
Regarding shade tolerance... I have used only mono crystalline panels on my boats since the 70s, so have no basis for comparison, but this is how mine handle it... A VERY dark shadow from something "close" like the boom, really knocks down their performance. This is why I spread my panels about the boat
, and added Schottky, one way, BLOCKING diodes in the + wires. (Not to be confused with BYPASS diodes in the panels) "Bypass" diodes are to prevent backflow issues within the panel, where as my "blocking" diodes prevent backflow between panels. I go under the assumption that one panel will be totally shaded most of the time, so a slight V loss from the diodes is a better option, in my application, than not having them. IMO...
Regarding cloudy days... we sized our array so that they produce TWICE our daily need on a good sunny day. This way they STILL bring our batteries
all the way back up on really cloudy days. It just takes until sundown, rather than by 10:00 AM! ONLY on the very darkest of threateningly overcast days, do we need to crank the engine
. (about 10 times per year)
On white/cloudy, overcast, but "bright" days, that still require sun glasses, we get about the same performance as clear, sunny days!
Far away shadows from rigging have little or no effect.