Have you done the math? My math says batteries cost more than buying power from PG&E, regardless of time of use rates.
Power costs me $0.15, $0.30, $0.45 /kWh depending on time of day.
AGM batteries cost $0.40/kWh to replace after reaching the manufacturer's spec'd cycle life.
FLA costs $0.20/kWh (and demands more of my time.)
PV costs me $0.05/kWh.
So I think the most cost-effective is to produce excess power, backfeed the grid when it is up
I am currently back feeding the grid around solar noon, but then buying it back at a much higher rate in the evening. For me, this is as much about not getting ripped off on the "Time of Use rate" than it is trying to truly profit. I think SCE makes plenty of money, and does not need to take more from me. They take my extra power and profit from it, and then want me to pay for it also? But I will also try running the numbers again.
With new batteries, I agree, they really can't save money over the cost of grid power. If I use the cost of my inverter and batteries (and a rough estimate of all the little stuff) I am in about $6,000 thanks to a great deal from Battery Hookup. My pack measures about 17 KwH of useable storage. They are basically new cells and I should get a solid 3,000 cycles of 60% DoD. So 10 KwH x 3,000 = 30,600 KwH for $6,000 = $0.20 per KWH cycled. That is right in the ballpark. If I move my over production to the peak rate $0.38 time, it can actually start saving some money.
I truly think the utilities should be paying home battery owners more when we are actually helping to stabilize the grid. We become the peaker plant to shove power out to the grid when it is needed most. In the past, that was the most expensive power for them to generate as it needed to go online fast, and if it ran at a loss, it was accepted to keep the grid up until they could ramp up more coal etc. If people with solar and a battery can hold off noon production by storing it, and then provide the boost needed in the evenings, we should get paid a premium, not billed extra. If I was able to stay on my old tiered billing, I would be able to stay in tier 1 90% of the year. But no, have to be "Time of Use" now, and the cheapest rate is more than tier 1 was. So we use less power, they have to charge us more for it. Thanks, NOT!
Our water company did the same crap. They demanded we all use less water, handed out penalties for using lawn sprinklers, required all new home fixtures and appliances to use less water, and then, they complained that revenue was down, so they increased the fixed charges and the cost per gallon so we ended up paying the same amount (or more) for less water used. How great is that?
Eventually my battery bank is going to starts dying. At that point I only have to replace the batteries, not the inverter and the rest of the install. My hope is that I can get another battery bank then (in 5 to 8 years by my math) that will match that cost per KwH cycle. Maybe the tech or used EV cells will get cheaper by then. That was another reason for the Schneider inverter. If some new battery comes out, or I go to a different chemistry, I should be able to program it to work just fine. Up at 48 volts, it should be easy to find a grouping of cells that fall in the operating range of 44 to 60 volts. Even my BMS can take cells from 2.0 to 5.0 volts each, and up to 24 cells. So I can try all kinds of cells.
The other fun thing I am looking at is the new bidirectional EV chargers. Right now you can get a unit that will work on the Nissan Leaf. It can charge the car at up to 7,000 watts, but it can also pull from the car at 7,000 watts to feed your home. This turns your car into a 60 KwH power wall. Now if you are at work with the car while the sun is shining, it does not help too much. But for my brother, he and his wife both have Chevy Bolts, hers is home and could charge on the sun, and then when he get's home, push half the free solar charge into his. Too bad they don't have a bidirectional for the Bolt yet, it uses a different connector and the data link is not supported yet. My current car is only a hybrid, not a plug in yet, but it is 7 years old with 175,000 miles, so I am looking. Being able to use the car battery to power my home will be on my list of options.