Powershell script to web login and export data -- 2

We need a power shell script that will run once per day via a scheduler and login to a specific website automatically (via Mozilla preferable) in order to export to a text or csv file specific numeric data. Those data changing per hour, so the next day the exported data will cover - delete the previous. Unfortunately the credentials can not provide due to security reasons. We can schedule - prepare a session under our machine for any tests you will need.