You can export invoices, customers and payments from Printavo to a CSV file. This file can be added My Account > Import/Export Data
You will be able to download your invoices from a specific date range. Once you have selected your date range, click Download and an email will be sent to you with the exported file to download.
Also, you or a customer can always download an invoice as a PDF. Within the invoice head to More Actions > Public Invoice View, and from there you will see a "Download PDF" button.