Currently exportCsv / exportExcel exports only the main data in the grid.
However you can include the summary data in csv file by appending the summary row in dataModel.data (without refreshing the view) just before invoking
http://paramquery.com/pro/api#method-exportCsv and removing the row after that.
steps:
1) dataModel.data.push(summary row)
2) exportCsv or exportExcel
3) remove the row from dataModel.data using splice.
http://www.w3schools.com/jsref/jsref_splice.asp