# get already active Excel application or open new
my $Excel = Win32::OLE->GetActiveObject('Excel.Application')
    || Win32::OLE->new('Excel.Application', 'Quit');


    
# open Excel file
my $Book = $Excel->Workbooks->Open("C:\\tester.xls");
my $Sheet = $Book->Worksheets(1);

$Sheet->Cells(22,31)->{'Value'} = $open;