Who owns Solar City?
ISTR that there is a pretty tight connection between the ownership of Solar City and Tesla...
A home battery does make perfect sense for people with solar panels. In California, solar production is essentially zero at 6PM PDT, where peak power consumption occurs 7PM PDT in the summer. This likely to lead to some pretty hefty rates for usage in the 6PM to 9PM time frame, so running off a battery during that time will likely bring significant savings in electric bills especially if the CPUC starts setting rates that have some connection with the reality of providing service. The CPUC and CalISO are already encouraging people to put solar panels on west facing roofs.
I've been researching batteries for exactly this purpose, and while lead-acid batteries intended for stationary service will do the job, their size is a bit impractical.
FWIW, the high at home was 33C today.