I would recommend that you use RMAN to create your backups. You can create a script that the operator can run that will generate hot full, hot incremental or cold backup. This is preferable to stopping the service especially if you are stopping the service through the windows interface. If you stop the service through the windows interface it issues a Shutdown Abort which will leave you with inconsistent datafiles and has the potential of corrupting your database.
In the script you can specify a user that has sysdba privileges and then the operator can log on with their own account and run the script.