However, the cost of having 2 full batteries (ie panel - powerwall - car battery) would be massive in today's world, where batteries are already a huge cost.
PS: A 2% change per year is actually well within normal variations.
Here is a two page CPUC brochure (PDF) about it: http://www.fishnick.com/pge/Decoupling_Explained.pdf
Power companies are heavily regulated and so are power rates. Their business model is dictated to them.
http://www.forbes.com/sites/uciliawang/2011/08/08/chevy-volt...
http://www.sandc.com/products/energy-storage/ces.asp
The grid of the future might be decentralized and autonomous.
Instead, you find all the talk is about the magical environmental benefits of this plan (which i expect are actually pretty slim in and by itself), without any implementation details of how california will prepare for it to happen. They talk instead of how they are going to force automakers to do the "right thing", with no self-introspection that "holy shit we may need to do some work too".
Except, with some of the suggested solutions, like rooftop solar/etc, we know that over time it causes the normal power usage to invert (see germany, which no longer has a mid-day peak).
That is, the trough is no longer at night, but in the middle of the day.
Ever barring this: think of this another way: If you suddenly increase nighttime usage by several thousand percent, it's unlikely to be a trough anymore, and pretty far into a spike.
THe carport amperage/voltage is usually around 240v/30 amp. This is a lot, and definitely a ton more than the average power usage of a home at rest or even with the AC on.
At that voltage/amperage, it would take 10+ hours to charge an 85kwh battery
If you go to 240/50 amp, it's about 7 hours, but again, even more of a factor than the average hours residential usage.
This is like having 4-5 high end electric oven on full blast for 7 hours.
(or in maker terms: i have a really nice 3hp table saw, really nice 3hp jointer, planer, cyclone dust collector, cnc machine, vacuum clamp, etc. Having them *all running at once takes less power than the carport :P)
I would bet, in fact, that it would shift peak residential to nighttime by a significant factor (to put some perspective on this: average residential usage is like 25-30kwh a day, so 85 at night would definitely be "huge")
(Again, it's not that i don't think there are solutions, but in grand california tradition, they chase some magically happy utopia without actually ever planning for the long term consequences, then act shocked when they happen)
Given that converting all cars in CA to electric would seriously stress the infrastructure[1], yet they are not doing anything to improve that infrastructure, I can't say i'm impressed with california's long term thinking here ...
[1] Some back of the envelope math: there are 20,665,415 registered autos in CA. I'm going to exclude light trucks and trailers which make up another 12 million, and essentially double our numbers because they need more power/etc. <10% of autos are electric, but i'll just remove 10% to round nicely, and say "18 million non-electric vehicles. If they move to 85KWH cars, depleted and charged once a week, now we have an additional 85KWH x 18 million cars of electric power being used once a week. That's 1,530,000,000 KWH or 1530 GWH extra that needs to be generated and distributed every week. That's 79,560 (52x1530) GWH a year.
California produces 200,000 GWH a year, mostly from natural gas: http://energyalmanac.ca.gov/electricity/electric_generation_...
So they need to produce and distribute 40-50% more electricity than they do now to make this happen. Note that generation ability has not really moved from 2000. In fact, it's gone down! If they also want to meet their goal of moving generation to 33% renewable energy by 2020 (and eventually all of it), and thus provide this capacity without staying on gas, they'd basically have to double all available renewable energy output.
That's just the generation side. Then they have to make sure they can distribute it.
Don't worry though. I'm sure all the right people talk and plan this stuff together, and it's not just one part of the government doing something without thinking about the long term consequences that need to be planned for elsewhere - that never happens in government :)
Of course, the numbers above are just spitballing to show there is thinking that appears to not be happening (as to whether it's a good idea or not, i actually don't care whether my car is electric or not :P). The average car is driven 15 miles a day, so maybe it takes 2 weeks to deplete your 85kwh battery. But generally, no matter what sane thing you do to these numbers, halve them, double them (maybe cheaper cars use crappier batteries/engines, maybe they mean light trucks too, etc), it's still "a lot of extra to plan for". Even a 1-2% change in electrical capacity is serious business.
Until they actually have a serious plan for solving these issues, i'm just going to look forward to the lawn signs saying "80 volts is the new 120".