All this talk about solar made me decide to upgrade from a PWM to a MPPT controller and change my eight panels in parallel to series/parallel. I have two banks of 4 panels rated for 12v (approx. 17.x volts open circuit voltage) and all are presently wired in parallel. The wiring runs are long (20+ feet) and I can reduce losses by going with higher voltage. One bank is on each side of the boat.

The MPPT controller I'm getting can down-convert as high as 72 volts in solar output to a 12v battery system.

So which is more efficient...

A) 4 parallel pairs of series panels at nominal 24v (2x17v=34v actual), each parallel pair having output diodes to make the overall array more shadow-resistant? (Two banks each side of the boat).

B) 2 parallel banks of series panels at nominal 48v (4x17v=68v actual), each made up of 4 panels in series. (One bank each side of the boat). Blocking diodes used only on the output of each series, in event one side of the boat is in the shadow of sails/rigging.

I'm leaning toward option B, although option A would be more tolerant of partial shadows and faults in the "real world". Thoughts?