I had this exact same issue. I called nautilus and here was the explanation.

The solar company provides you “credits” those credits get applied to the CMP bill and what isn’t used (or accepted) you still have to pay community solar for in a separate bill just to them. They said this would be changed within a few years but honestly it wasn’t sold to us this way and I’m fairly unhappy with it. Not only do I owe our overlords CMP whatever the want to charge I’m also in the hole for what the solar company has credited me, all for my benefit I’m sure.