Outlook.com calendar csv export with custom field (private office 365)

Hey Folks
Looking for a Script to export multiple calendars from specific outlook account (running several accounts in local outlook 365 single/private version.
The Calendars are hosted on a http://outlook.com/ account.
I need a csv or excel as export.
I d like to configure a windows task to automate the script without outlook running.
Think PowerShell is the way to go (or are there other approaches?)
Tried several scripts found in the net, but was not successful until now. Any help highly appreciated.
Thanks,
Daniel