Hi there,

If using the latest version of Excel package, you could use \koolreport\excel\Table widget in an excel export template file "MyReportExcel.view.php". Set its property "showFooter" => true and make sure your columns' metadata have have a "footer' property:

"column1" => [
    "type" => "number",
    "label" => ...,
    "footer" => "sum"
]

It works very similarly to the \koolreport\widgets\koolphp\Table widget. Let us know if you have any question. Thanks!