It is possible to connect strings of different orientations on a single input (inverter or battery pack), as long as all modules of each string are kept in the same orientation. In this case the currents of different strings will be different (according to the sun orientation) but will mix at about the same voltage. This results in negligible mismatch losses.

Putting modules in series in different orientations will yield complex I/V characteristics behavior analogous to partial shadings effects. This can result in high losses and eventually hot spot risk.

You can have a look on the special tool "Electrical behavior of PV arrays" in the "Tools" part of PVsyst for visualising and understanding these phenomena.