The Islandora Solr facet pages module creates an alphabetical "A to Z" browse from metadata indexed in Solr. The "facets" are the fields that Solr will search in to build the A-to-Z browse. You can set up multiple A-to-Z pages.
This module requires the following modules/libraries:
Release Notes and Downloads
Install as usual, see this for further information.
Configuration for this module is located in Administration > Islandora > Solr Index > Facet Pages (admin/islandora/search/islandora_solr/facet_pages)
To set up an A-to-Z browse page for any Solr field:
The example in the above image creates an A-to-Z subject browse: