On the Web, I found that some Californians do use their units to save money with the TOD differential.
Here in Phoenix, I chose a time-of-day rate structure that charges 24.09c/kWh during the peak summer hours of 2-8PM, and 7.3c/kWh outside that peak period. Or I could choose a fixed rate of 11.57c/kWh all day.
Even before I installed a DIY solar+storage, the TOD rate saved me a bit of money already, simply by programming my pool pump to avoid the peak period, plus installing a timer to cut out the water heater between 2-8PM (and avoiding using a lot of hot water during that period).
I looked on the Web and found the following rate by Southern Cal Edison: 41c/kWh for 4-9PM, and 26c/kWh for off peak. But for people with a residential energy storage system, the rates are 43c and 16c.
With an energy storage system, you want to arbitrage between the 2 rates, and that's 43c minus 16c, or 27c/kWh. But daily cycling of the battery will shorten its life, so that must be taken into consideration.
Now, Tesla guarantees that the Powerwall 2 will retain at least 70% of its initial storage capacity after 10 years or 37.8 MWh of throughput, whichever occurs first.
That 37.8 MWh or 37,800 kWh multiplied by $0.27 is $10,206. That's roughly the installed cost of a Powerwall 2 with 13.5-kWh capacity. The unit pays for itself after 10 years, and of course it will still has 70% of capacity left, so there's a significant residual value.
References:
1)
https://www.sce.com/residential/rates/Time-Of-Use-Residential-Rate-Plans
2)
https://www.tesla.com/sites/default/files/pdfs/powerwall/powerwall_2_ac_warranty_us_1-4.pdf