Looks like Template Grids don’t support the standard Export to Excel funtionality. What you could do is use the “Excel Exporter” widget from the marketplace and configure that to your needs. I have not yet used the excel exporter though so I can’t tell you any tips, sorry.
Hope this helped.
Indeed the template grid doesn't support excel export out of the box. The datagrid however does. Reason is, the datagrid has columns and rows, like excel has. And thus exporting a list from a datagrid to an excel uses the format of columns of the datagrid. As an template grid doesn't have data columns, but shows objects in columns and rows, this doesn't convert into an excel sheet.
So if you want to export, than the easiest way is to use a datagrid instead. or do it the complex way by implementing the excel export module from the martketplace.
Just a note from a fellow Mx develoepr: dont use the template grid at all. as this causes more frustration than it solves. Better option for a styled list is the List view.