Error message:
Fatal error: Maximum execution time of 30 seconds exceeded in /var/www/elo/moodle/lib/phpexcel/PHPExcel/Style/NumberFormat.php on line 453 Call Stack: 0.0021 801064 1.

() /var/www/elo/moodle/mod/feedback/analysis_to_excel.php:0 30.2398 39502416 2. feedback_excelprint_detailed_items() /var/www/elo/moodle/mod/feedback/analysis_to_excel.php:201 30.2417 39525568 3. MoodleExcelWorksheet->write_string() /var/www/elo/moodle/mod/feedback/analysis_to_excel.php:268 30.2431 39527912 4. MoodleExcelWorksheet->apply_format() /var/www/elo/moodle/lib/excellib.class.php:193 30.2432 39527928 5. PHPExcel_Style->applyFromArray() /var/www/elo/moodle/lib/excellib.class.php:421 30.2432 39532848 6. PHPExcel_Style->_clone() /var/www/elo/moodle/lib/phpexcel/PHPExcel/Style.php:0 30.2436 39558480 7. PHPExcel_Style_NumberFormat->_clone() /var/www/elo/moodle/lib/phpexcel/PHPExcel/Style/NumberFormat.php:0

Extending the execution time to 300 seconds was a workable workaround.

The feedback had 928 respondents en 8 questions. The total size of the exported Excel file was 56 kB