SQL Server 2008 R2 has two new additions to its Analysis Services (BI) hat, PowerPivot for Excel and PowerPivot for SharePoint.

Similarly SQL Server 2012 also includes new features for PowerPivot component that features for both SharePoint and Excel. To check in specific to what is new in this regard you can refer to What's New (Analysis Services).

Further to the topic when we talk about SharePoint then its worth to talk about multi-server farm, which means there are two or more PowerPivot for SharePoint instances. In this case of upgrade process it is essential to upgrade each server individually before proceeding to the other server. By design a full upgrade cycle must be followed by using SQL Server Setup to upgrade program files and then SharePoint upgrade actions to configure the ugpraded services.

PowerPivot brings a configuration tool which is one of SQL Server shared features, which means when you are upgrading the platform all the shared features must be upgraded at the same time, for more information review Upgrade to SQL Server 2012 Using the Installation Wizard (Setup) link.

Another point to note here is when you are upgrading PowerPivot tool it may not necessarily upgrade the workbooks (associated( that run on it, however the older workbooks that are created in previous version of PowerPivot for Excel will continue to work as before limited by previous version. So in order to expand the new features capability you must upgrade which is checked by Analysis Services OLE DB provider that is part of SQL Server version installation.

Data refresh operations are affected when you upgrade the platform, for PowerPivot there are certain data refresh schedules are set on the server. Say if the server is new version (2012) and hosting workbooks are in previous version (2008R2), then data refresh will no longer work for such workbooks. In order to re-enable the data refresh all the associated workbooks version must be upgraded too. You can upgrade each workbook manually in PowerPivot for Excel, or enable the auto-upgrade for data refresh feature. Auto-upgrade will upgrade a workbook to the current version prior to running data refresh, allowing data refresh operations to remain on schedule. For more information about this feature, see Upgrade PowerPivot for Excel and PowerPivot Data.

Further the topic of upgrading PowerPivot for SharePoint go through the points slated below: