The popular Google Add-on, Flubaroo, recently released a new feature for those users who do not have the option to share grades via email. You can now share grades via Google Drive.
From the "Share Grades" menu you can select the second option, which is the grade sharing method, and set it to Share via Google Drive (no email). Flubaroo will create a new folder structure (Flubaroo - Shared Grades) with nested assignment folders within your Google Drive. New Google Docs will also be created in each of these assignment folders, one for each of your students. You will own he documents, but the students will have comment access to them. No notification will be sent to the students, so you will need to instruct them to go to the Shared with Me folder to find their Doc. They can then move it into their Drive folder for easier access in the future.