Not directly related, re: the economics relating to arbitrage and whatnot...
When we think about "fair" and the ability and limitations re: arbitrage at the individual level, I think we may be missing a key point re: the economics of electric utilities. I'm not an expert and I may be entirely wrong about the following, but my understanding is that electric utilities are massively impacted when they cannot satisfy demand through their own generation and have to purchase supply on the open market. In particular, if/when these situations they can pay an order of magnitude or more for additional supply than it costs them to produce it on their own.
It feels to me like part of the equation here should be mechanisms to help us all collectively avoid such peaks...in this case, our interests align quite well with the utility because anything they do that increases their costs/decreases their profits will inevitably increase our costs.
The various opt-in programs that utilities now offer that allow them to reduce your demand are designed to help address that problem. But our batteries are doing the same thing -- twice over in fact, because not only does it allow us to sell solar capacity back during many of these peak periods but we're also lowering demand by drawing off battery at those times.
I think this is one reason why batteries are such an important part of the energy equation and why subsidizing them can make sense. It would be that much more amazing if we could have the batteries in our cars could integrate into the energy ecosystem like a power wall too.
Anyway, the point I'm trying to make is that maybe it isn't unreasonable for us to arbitrage...charge our walls at super-off-peak rates and provide it all back to the utility at peak rates...as long as we're willing to help them avoid the periods where they pay ridiculous rates for demand they cannot service on their own. Or at least it should be factored into the equation...we shouldn't just look at the individual economics, we need to look at the bigger picture.
True - But you're still time only time shifting the usage of power during peak. I don't see how utilities care if you time shift your energy from 12mn to 12n-6pm usage on your own (if you charge on their power and use on their power). Selling it back on power you bought from them at cheap (full arbitrage) is wrong. Right now, with TBC - Solar - we're optimizing generation to sell back at pk hours as a small scale generator. TBC-NonSolar is partial arbitrage already -- charge at night, use during pk hours. What's the difference with the car? (minus the free supercharger issue already mentioned).