Output as a download

output.php

<?php
$phpExcel = new PHPExcel();
$phpExcel->getActiveSheet()->setTitle("My Sheet");

$phpExcel->setActiveSheetIndex(0);
header("Content-Type: application/vnd.ms-excel");
header("Content-Disposition: attachment; filename=\"filename.xls\"");
header("Cache-Control: max-age=0");

$objWriter = PHPExcel_IOFactory::createWriter($phpExcel, "Excel5");
$objWriter->save("php://output");
exit;