Connecting to Midnight Box (sub-circuit breaker panel))

Anyone connect their unit to a midnight box, which is a “sub-panel” circuit breaker box connected to the main electrical panel of the house. The sub-panel has only, typically, 4-8 lines (which are branched off of the main electrical panel to the sub-panel) that can be utilized in case of a power blackout; it can be connected to the solar generator for its power. What kind of connection was used between the solar generator and the sub-panel box? RV connector? Or ???

Sounds very interesting. I’d like to know myself. I’m thinking along the lines of having my AC200P being more than just a backup.