What is PHPExcel? (PHPExcel for OpenCart)

PHPExcel is a PHP library providing an ability to work (read/create/edit) spreadsheet files (formats: .xls, .xlsx, CSV, .ods, and some others).
Official PHPExcel library page on GitHub https://github.com/PHPOffice/PHPExcel.

This library is used in some older versions of our modules  Related Options (on opencart.com), Related Options PRO (on opencart.com), Product Option Image PRO (on opencart.com), Product Option Image Ultimate (on opencart.com) and Parent-child Options (on opencart.com) for their import/export features. PHPExcel library files is not included in the module packages, so it should be installed additionally (but it is required for the import/export functionality only, thus there is no need to install PHPExcel if you are not going to use the import/export features). 

Versions of the modules for OpenCart 3.x install the library automatically (when necessary). For OpenCart 2.x manual installation is necessary.

How to install PHPExcel for OpenCart 2.x :

1. Download the last PHPExcel release version from the official site https://github.com/PHPOffice/PHPExcel/releases
2. Create the directory "PHPExcel" in the OpenCart "system" directory (to have the path from OpenCart root "/system/PHPExcel/")
3. Copy the directory "Classes" (with the entire contents) from the downloaded PHPExcel package to the OpenCart directory "/system/PHPExcel/" (created on the previous step)