Solr Field Mapping

Is there a case-insensitive multi-valued field available?
I’m indexing dcterms_subject as an _ss field but will match only match subjects with exact capitalization. All the case insensitive fields I’ve found so far have not been multivalued.

“_t” (text general) is case insensitive by default, but not “_ss” (multiple strings), so you will have to update the solr schema. See https://stackoverflow.com/questions/8240329/solr-case-insensitive-search
Else you can create a specific solr data type that store values as lower case in the module, then to lowercase the request queries.