The cost is key here though, at $2m or potentially lower you're paying just $1-2k per home and maybe $100 a year maintenance thereafter. Not a bad price overall

The cost is key here though, at $2m or potentially lower you're paying just $1-2k per home and maybe $100 a year maintenance thereafter. Not a bad price overall for what you get. In Australia at least, electricity costs $1-2k per year per household. Some napkin maths tells me that at 15MWH consumption per year this sort of storage could make solar (at $50 per MWH) pretty viable. As in, potentially below $1k per year even if you build enough storage to cover 80% of the day.