mppt vs pwm

I'm still confused about the effect of partial shading, and which external wiring , series or parallel, will eliminate the entire panel/array from shutting down?

(I do have a pretty good handle, I think, on the use of by-pass diodes in the panels themselves, to stop hot spots from overloading the entire panel)

So, if series/parallel is not an option, which way is best, where partial shade is concerned; series or parallel?

Thanks.