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

$application->{'Visible'} = 0;
my $workbook = $application->Workbooks->Add();
my $worksheet = $workbook->Worksheets(1);

my $now_time = time;
my ($sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst) = localtime($now_time);
my $start_time = $now_time - (($mday > $bscope ? ($mday -1) : $bscope) * 86400);

$worksheet->Cells(1, 1)->{'Value'} = 'Wochentag';
$worksheet->Cells(1, 1)->Font->{'FontStyle'} = "Fett";
$worksheet->Cells(1, 2)->{'Value'} = 'Datum';
$worksheet->Cells(1, 2)->Font->{'FontStyle'} = "Fett";
$worksheet->Cells(1, 3)->{'Value'} = 'Arbeitszeit (h)';
$worksheet->Cells(1, 3)->Font->{'FontStyle'} = "Fett";

my $wosum = 0;
for (my $t = $start_time, my $i = 2; $t < $now_time; $t += 86400) {
    my ($sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst) = localtime($t);
    my $iDay = sprintf ("%04d-%02d-%02d", $year + 1900, $mon + 1, $mday);
    (my $tt = $arbzeit{$iDay}) =~ s/,/\./;
    if ($mday == 1) {
        $worksheet->Cells($i, 2)->{'Value'} = 'Summe';
        $worksheet->Cells($i, 2)->Font->{'FontStyle'} = "Fett";
        $worksheet->Cells($i, 3)->{'Value'} = $wosum;
        $worksheet->Cells($i, 3)->Font->{'FontStyle'} = "Fett";
        $wosum = 0;
        $i+= 2;
        $worksheet->Cells($i, 1)->{'Value'} = 'Monat ' . ($mon + 1);
        $worksheet->Cells($i, 1)->Font->{'FontStyle'} = "Fett";
        $i++;
    }
    $worksheet->Cells($i, 1)->{'Value'} = qw/So Mo Di Mi Do Fr Sa/[$wday];
    $worksheet->Cells($i, 2)->{'Value'} = $iDay;
    $worksheet->Cells($i, 3)->{'Value'} = exists $arbzeit{$iDay} ? $arbzeit{$iDay} : "-";
    if ($tt > 10) {
        $worksheet->Cells($i, 3)->Font->{'ColorIndex'} = 3;
    }
    if ($tt == 7.6) {
        $worksheet->Cells($i, 4)->{'Value'} = 'Urlaub?';
    }
    if ($wday == 0 || $wday == 6) {
        $worksheet->Cells($i, 1)->Font->{'ColorIndex'} = 5;
        $worksheet->Cells($i, 1)->Font->{'FontStyle'} = "Kursiv";
        $worksheet->Cells($i, 2)->Font->{'ColorIndex'} = 5;
        $worksheet->Cells($i, 2)->Font->{'FontStyle'} = "Kursiv";
        $worksheet->Cells($i, 3)->Font->{'ColorIndex'} = 3;
        $worksheet->Cells($i, 3)->Font->{'FontStyle'} = "Kursiv";
    }
    $wosum += $tt;
    if ($wday == 0) {
        $i++;
        $worksheet->Cells($i, 2)->{'Value'} = 'Summe';
        $worksheet->Cells($i, 2)->Font->{'FontStyle'} = "Fett";
        $worksheet->Cells($i, 3)->{'Value'} = $wosum;
        $worksheet->Cells($i, 3)->Font->{'FontStyle'} = "Fett";
        $wosum = 0;
    }
    $i++;
}
$application->{'Visible'} = 1;
$workbook->{'Saved'} = 1;