Originally Posted by Autumns Wind
So is it worth the expense of a multi string solar panel, then one with just a single string. I mean is the extra cost worth it?
Too general a question. This really depends on your installation
voltage are you charging
(and it's not just "12V" - the difference between charging
at 13.8 vs. 14.4V can be significant as you move solar modules off their optimum I-V curve)?
What type of charge controller are you using? Can it do step-up or step-down voltage changes (most MPP controllers can do one or the other, usually step-down, but PWM controllers can't make voltage changes)?
What are the shading characteristics of your installation
location? If you are installing two panels side-by-side, or a multi-string single module and they will likely both end up with hard shade at the same time then splitting up the system makes no sense. This can be particularly true of multi-string units, if two cells in different strings are right next to each other in the shade...
Really, the bottom line usually ends up installing as much solar as you can fit and then accepting the limitations that installation on a boat brings.