使用PHP从网站解析信息

Question

I want to extract information from this spanish website: http://www.esios.ree.es/web-publica/ , but it seems that the website downloads first a HTML, which I can get whith the function file_get_contests, but afterwards it downloads more code that I can't get and unfortunately it is the part which code it is interesting for me. I can see this code from the navigator, but not downloading using this function.

The code I am using for the problem is below:

<?php
  echo "<h1>Hello Venancio</h1>";
  // fetch contents from http://www.esios.ree.es/web-publica/
  $url = 'http://www.esios.ree.es/web-publica/';
  $content = file_get_contents('http://www.esios.ree.es/web-publica/');  
  $DOM = new DOMDocument;
  $DOM->loadHTML($content);  
  $elements = $DOM->getElementById('panel01');  
  $data = array();
  foreach($elements as $node){
    foreach($node->childNodes as $child) {
      $data[] = array($child->nodeName => $child->nodeValue);
    }
  }  
?>