Full HTML in custom form fields

Today I have been working with a custom module that contains a form. Initially I used textarea controls to my form fields but I changed it by text_format instead textarea.

$form['reject']['reject_comment'] = array(
'#type' => 'text_format',
'#title' => t('Reason for reject'),
'#disabled' => !(user_access('Approval ep_change') || user_access('Development ep_change')),
'#default_value' => isset($ep_changes_entity->reject_comment)?$ep_changes_entity->reject_comment:'',
'#required' => FALSE,
'#cols' => 60,
'#rows' => 5,
);