I think you would see both, but not quite ubiquitous like GP claimed unless in a region with trouble keeping their grid up. Utilities will do the cost-rational

I think you would see both, but not quite ubiquitous like GP claimed unless in a region with trouble keeping their grid up. Utilities will do the cost-rational thing and deploy those batteries where beneficial, and households will adopt them as well because there is always the chance that an outage can happen between the big battery and your house. Or, if the entire system falls over for some reason, you can still be an island unto yourself with solar + batteries re: hot water heaters - it should be noted that hot water and steam delivery systems exist and are quite effective(commonly derived from cogeneration sources) e.g. https://en.wikipedia.org/wiki/New_York_City_steam_system https://en.wikipedia.org/wiki/New_York_City_steam_system