Add a translatabe text into panels
If using Drupal 6, ensure these edits are within the settings.php file, as this is where the translation will take effect. 

If using Drupal 7, there are a few reasons why this may not work. Most usually, if the text you are translating contains anything that needs to be substituted (i.e. using %user:name etc.), then the text will be substituted before being passed to t(), and as such will not work! Also, the functionality of t() in Drupal 7 for attributes and variables is limited, so perhaps an additional module will be helpful. 

For solutions using additional modules: Place the text in a basic page,  you can then use Entity translation to handle the languages and translation. @pedrosp also suggests that "to avoid SEO duplicated content issues, install Rabbit hole module and use the redirect to your panel page for those nodes."

Also, i18n has some solutions to tranlsate text within panels. It may take some playing around with however, to match the intended functionality of your site.

Finally, @Letharion has shared before some custom code to "force" a title to become translatable, perhaps playing with this to focus instead on where you would like your translatable content would also help:

/**
 * Implements hook_panels_pane_content_alter().
 */
function HOOK_panels_pane_content_alter($content, $pane, $args, $context) {
  if ($content-&gt;title) {
    $content-&gt;title = t($content-&gt;title);
  }
  return $content;
}


Hope this is of some assistance!