How to run Romex cable to Enphase Combiner box 3?
What you can do is run your Romex as planned to a junction box on the inside wall and run conduit from the junction box through the wall to your combiner box. Splice your 10/2 Romex to #10 AWG THHN single conductors with wire nuts and run the THHN in the conduit to your combiner box. That should keep everyone happy.