PHP encoding Umlauts in .csv for Excel

I’m working on a PHP script that creates a .csv file from some data.

Unfortunately, in Excel Umlauts are not displayed properly: Löl becomes Löl (this is just in Excel, in Apple’s Numbers, Atom and Textedit everything looks fine).

I have tried hundreds of functions to try and get the encoding right (see the commented functions below). Could someone please tell me what I’m doing wrong?

$rows = json_decode('[["Löl"]]');

foreach($rows as $key_row => $row) {
  foreach($row as $key_cell => $cell) {
    // $rows[$key_row][$key_cell] = utf8_decode($cell);
    // $rows[$key_row][$key_cell] = iconv('UTF-8', 'Windows-1252', $cell);
    // $rows[$key_row][$key_cell] = mb_convert_encoding($cell, 'UTF-16LE', 'UTF-8');
    // iconv('UTF-8', 'Windows-1252', $rows[$key_row][$key_cell]);
    // mb_convert_encoding($rows[$key_row][$key_cell], 'UTF-16LE', 'UTF-8');
  }
}

$temp = fopen('php://memory', 'w');
foreach($rows as $row) {
  fputcsv($temp, $row, ';'); 
}
fseek($temp, 0);
header('Content-Type: application/csv');
header('Content-Disposition: attachment; filename="test.csv";');
fpassthru($temp);

Answer

The following conversion to UTF-8 BOM worked:

foreach($rows as $key_row => $row) {
  foreach($row as $key_cell => $cell) {
    $rows[$key_row][$key_cell] = chr(239) . chr(187) . chr(191) . $cell;
  }
}

Thanks for everybody who chimed in 🙂