I addressed the high-level similarities and common goals of the two protocols here:
@thisismissem.social used to work on Solid and I believe she’s in the process of collecting some longer-form thoughts.
@kjetil.kjernsmo.net co-edited the original Solid spec.
The technologies are too different for that, but imo there’s a very straight forward interop story in the common use of PLC-based web identities with multiple different data storages, i.e. a web ID that uses atproto PDS when I’m using it on an AT platform, and it uses a Solid Pod when I’m using it on a Solid platform.