SAE-J2847 includes "how to convert your building side to supporting BPT grid works, and pairs well - it looks - with ISO 15118-20 BPT. (and reasonably well with ISO-15118-2 and the BPT extensions in SAE-J2847). Anyway, supporting AC grids requires some additional electronics both in battery systems and in the local hookups.

I haven't explored the actual space much, as I work on ISO 15118-20 for busses, and a bus as a local grid backup scales pretty well. (and even then, I work protocol level, not electrical).