public function backgroundCell($color, $cell=null, $row=null){
        $color = str_replace("#", "", $color);
        if(!is_null($cell)){
            $this->x = $this->getColumnName($cell);
            $this->y = $row;
        }

        $style = array('fill' => array(
            'type' => PHPExcel_Style_Fill::FILL_SOLID,
            'color' => array('rgb' => "$color")
        )
        );
        $this->engine->getActiveSheet()->getStyle("{$this->x}{$this->y}")->applyFromArray($style);
    }