Had the same problems with PHP-generated CSV files.
Excel ignored the BOM when the Separator was defined via "sep=,\n" at the beginning of the content (but of course after the BOM).
So adding a BOM ("\xEF\xBB\xBF") at the beginning of the content and setting the semicolon as separator via fputcsv($fh, $data_array, ";"); does the trick.