Tesla actually underhypes the Powerwall 2. It's better than most people realize. See: capabilities of the backup gateway. It islands existing grid tie solar systems and allows these systems to generate electricity for household loads and/or Powerwall charging during grid failures. Usually grid tie solar systems are disabled during grid failures to prevent them from exporting electricity to the grid.

https://www.youtube.com/watch?v=HxAbd-kanI8

Tesla mentions this capability, but most people shopping for energy storage don't realize what it would cost to do this with gear from other manufacturers (SMA for example). Some storage providers don't offer any backup capability at all. Enphase is the saddest example of this. Enphase tried to convince customers that they shouldn't demand backup capabilities from their solar energy storage systems, and Tesla is actually towing a Tiny house around Australia that uses Enphase microinverters with a Powerwall 2 offgrid. Enphase's own AC Battery provide no backup capability at all or a way to run off grid.

I sell solar power systems in New Zealand and the Powerwall 2 makes every other storage solution look stupid at the moment when considering price per warranted kW/h and features. I can't sell my customers a Powerwall 2 yet, but I advise against buying systems that I can sell them from Panasonic, LG, Sonnen, Enphase, etc. The whole storage industry needs to understand that the Powerwall 2 is real (get over the shock) and that if they don't cut their prices roughly in half---look at Aquion.

https://cleantechnica.com/2017/03/15/aquion-energy-files-cha...

Nice battery. Too expensive.