To send the middle pane output to a file, go to the Edit menu and select Send 'Middle Pane' Output to File.

A file is created in the directory defined in Tools > User Preferences > Outputs > Output File Directory.
If the Output File Extension is set to .csv in Tools > User Preferences > Outputs > Output File Extension, then an Excel file is created.
If the file is set to auto-open in Tools > User Preferences > Outputs > Output File Auto Open, then the file opens automatically.