I was recently working at customer location on PowerPivot project. It was quite complected as this is relatively new technology and we all are exploring what this technology can do and what it can bring to us on table in real life experience. During this implementation the project design document needed specification regarding Data Refresh rates. It was a bit complected as there were various components and modules to the project and selecting the refresh rates means understand all of the requirement as well understanding our implementation in and out.
I referred following white paper from Microsoft before I move further in the project and found it very helpful and it helped me understand the implication of various data refresh methods and its capacities.
Following is the summary of the whitepaper.
The purpose of PowerPivot for SharePoint is to allow users to share their PowerPivot workbooks in a secure and scalable environment. To ensure that you are sharing and collaborating on the most recent data available to you, PowerPivot for SharePoint provides a data refresh feature that lets you automatically update PowerPivot data in an Excel workbook. This white paper describes in detail the data refresh feature in PowerPivot for SharePoint. It starts by explaining the steps for setting up a data refresh schedule in SharePoint, and then it continues with an in-depth view on how data refresh works on a SharePoint farm. Both administrators and the business analysts who author and manage PowerPivot workbook data can benefit from learning more about setting up and using data refresh in a SharePoint environment.
I suggest if you are facing situation like me download this whitepaper and read it before moving ahead in project.
Reference: Pinal Dave (http://blog.SQLAuthority.com)