This is more of a note to self as I am constantly self-confusing myself with how much data can be loaded into a PowerPivot model.
Basically, there are two things to consider, version of office one is running and whether a SharePoint deployment option is required.
First, whether one is running a 32 or a 64 Bit version of Excel. The 32 Bit version can only address 2GB of memory which effectively limits the size of the PowerPivot workbook to about 500-700Mb. The 64 bit version used to be limited to 4Gb file size in Excel 2010 but in Excel 2013 that limitation has been removed which means that the size of the workbook is no longer limited by the software but rather by the physical configuration of one’s machine.
Unfortunately, should one plan on posting that workbook in SharePoint, the SharePoint size limitation will dictate that only up to a 2GB file can be uploaded.
Here is the link for more information: http://office.microsoft.com/en-us/excel-help/data-model-specification-and-limits-HA102837464.aspx?CTT=5&origin=HA102893837