If you need a simple cost effective way to schedule backups your site collections, here’s the script for the job. Just add a scheduled task and your set. (how to add scheduled task)
Backup-SiteCollections
This script was designed to be scheduled and forgotten. This loops through all of your web applications and site collections and backs up each one individually. Each backup is prefixed with the current date and time. Old backups (3 days or older by default) are deleted. A log file is created to track the backup process.
