Contrary to popular misconception, Solr already supports hybrid search (the combination of keyword and vector-based search techniques)! Hybrid search can be used in retrieval, ranking, and even Solr's commonly-used "Learning to Rank" module. Alessandro Benedetti, Director at Sease and Apache Solr Committer and PMC member, explains more in a recent post, complete with code examples and explanation.
Learn how you can start using hybrid search in your deployments today - the complete post can be read here: Hybrid Search with Apache Solr