Thanks to JeremyW for posting CAISO link about future of TOU. They project forward to 2021. I liked this:
Rooftop Solar PV (ISO’s initial analysis assumed less than 5,000 MW, however the current estimate is in excess of 10,000 MW by 2021
They propose a 4th price, Super On Peak, for 4pm to 9pm Weekdays July and Aug only. Super Off peak 10am to 4pm for all weekends except those two months, plus weekdays Mar and April.
Sure this will incentivize batteries, but it is not clear whether they will really pay for themselves over their limited lifetimes.
I talked to a Powerwall 2 rep at Tesla Buena Park last Saturday. They have begun doing residential installs, 4 to 6 month backlog. To appease SCE and other utilities, Tesla has programmed the Powerwall to only charge from surplus solar power
, not from the grid, to minimize the arbitrage. The Powerwall is controlled by an App on your phone. Key parameters you can set include depth of discharge and top of charge. The full capacity of the Powerwall 2 is 13 kWh, but you need to set generous margins at the top and bottom of the battery if you want the battery to last through years of daily cycling.