The Power Pivot update story is somewhat convoluted. Excel 2013 integrates Power Pivot natively and the only way to get it updated (assuming the traditional MSI installation option) is through Office updates because the Office team now owns its distribution. Alternatively, if you have an Office 365 subscription, and have installed Office 2013 via the click-to-run option, then the Office and Power Pivot updates will be pushed to you automatically.
With Excel 2010, Power Pivot is an external add-in that can be updated from the Microsoft download center. While the Excel 2013 Power Pivot bits are installed in the %Program Files%\Microsoft Office\Office15\ADDINS\PowerPivot Excel Add-in, the Excel 2010 Power Pivot add-in is installed in a different location: %Program Files%\Microsoft Analysis Services\AS Excel Client\110.
The interesting side effect is that the Excel 2010 Power Pivot can be updated more frequently (for example, every time there is a SQL Server 2012 service pack or cumulative update), while Excel 2013 MSI users must wait for an office update (distributed via Windows Update for MSI installer) or via O365 updates.
To make the whole story short:
- If you have Excel 2010, use the latest Power Pivot bits available on the Microsoft Download Center.
- If you have both Excel 2010 and 2013, use the Microsoft Download center to get Excel 2010 updated. Excel 2013 won’t.
- If you have Excel 2013 only, wait for Office updates.