It certainly does seem that in the “now I have excess solar” ==> EV vs PowerWall equation that EV should come first … if it means deprecating a gas vehicle.
Then there’s …
I suppose in that regard you would start with converting a gas hot water tank to electric (hybrid if possible).
Seeing the way they do it in Switzerland & Germany (and Japan with cogen systems) I think the U.S. has a long way to go. Hopefully there will be some leapfrogging!
[Note: This is the end of 2015!]
Meanwhile there are long distance high-voltage DC grid interconnects that approach 95% efficiency, so there’s also that to consider. Anybody who thinks the “What should I do now with energy?” question is a simple one doesn’t have all the variables.