read only access to prepopulated solr
I can recommend taking a look at Sarnia 


  Sarnia allows a Drupal site to interact with and display data from Solr cores with arbitrary schemas, mainly by building views. This is useful for Solr cores that index large, external (ie, non-Drupal) datasets that either aren't practical to store in Drupal or that are already indexed in Solr.


I am using to search a solr index with emails imported with the dih