Erik Kostson
Ansys Employee

We can use solid 3D elements (if the model is not too large), or solsh190 elements - it depends if you are looking at only displacement or if you want a very accurate through thickness stress distribution (so stresses perpendicular to the shell surface), or shear distribution then a solid might be needed. Of course if the model is very large (and thin), then using solid 3D elements might be too heavy computationally.

Shell elements might be OK for a global shell model assuming it is not too thick (moderately thick) - see shell181 for more info on our shell elements. SO it all depends, on what we are looking at and are after (results).

There are also many discussion on the internet on this:
Also use a search engine and look for a discussion called:
Comparison of ANSYS elements SHELL181 and SOLSH190

This will give some good guidelines on what to use and what to watch out for.
All the best