As I am wanting to buy one of these, I'd like to know the actual name of it.
The name for a 3-part art piece seems to be "triptych" (translated via google from "triptychon").
Through some googleing I found "pentaptych" which doesn't seem to be correct as "pentateuch" is always suggested, but that seems to be specifically for the 5 books of Moses.
So the question remains: What is the right name for pieces of art that consist of 5 parts?