CsvValueBinder.php

<?php

namespace App\Utils;

use PHPExcel_Cell;
use PHPExcel_Cell_DataType;
use PHPExcel_Cell_IValueBinder;
use PHPExcel_Cell_DefaultValueBinder;

class CsvValueBinder extends PHPExcel_Cell_DefaultValueBinder implements PHPExcel_Cell_IValueBinder
{
    public function bindValue(PHPExcel_Cell $cell, $value = null)
    {
        if (is_numeric($value)) {
            $cell->setValueExplicit($value, PHPExcel_Cell_DataType::TYPE_STRING);

            return true;
        }

        return parent::bindValue($cell, $value);
    }
}