This isn't a "surge defense" approach... continuous charging loads are still going to pile on top of one another. In network protocols, we put randomization in place to ensure that we don't get oscillation effects - but that's not the issue here. The issue is total aggregate load of significant continuous loads. Whether you start at 12:00, 12:10, 12:30, or 1 -- or if you back-load it, whether you finish at 6:30, 6:45, 7:15, or 7:30, there will be a significant peak point. My hypothesis is that you simply won't see the "smoothing effect" that you're looking for.
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This isn't a "surge defense" approach... continuous charging loads are still going to pile on top of one another. In network protocols, we put randomization in place to ensure that we don't get oscillation effects - but that's not the issue here. The issue is total aggregate load of significant continuous loads. Whether you start at 12:00, 12:10, 12:30, or 1 -- or if you back-load it, whether you finish at 6:30, 6:45, 7:15, or 7:30, there will be a significant peak point. My hypothesis is that you simply won't see the "smoothing effect" that you're looking for.
Norbert
TSLA will win
Not sure what your point is. Obviously, charging loads will always pile on top of each other, when you have thousands of EVS. But the average charge time is probably less than 3 hours, which gives you many possibilities of distributing it overnight. For example, have early and late charge times overlap at the lowest point of the demand curve to the degree necessary to fill the "valley". Given the right software, why do you think that would be difficult?
Maybe I just haven't switched to the macro level conversation everyone is having around the national grid, but the issue is more localized to the urban/suburban distribution grid.
There is a limited amount of time available to charge between 12 am and 6 am. If every car uses between 3-4x the normal daytime load, and every car needs 3 hours (out of the 6-7 available overnight), even if perfectly distributed it still represents ~1.5-2x the normal daytime load on the local grids. No amount of software smarts randomizing the charge start is going to change that. It can reduce the impact by 50% perhaps, from 3-4x to 1.5-2x the daytime needs *if perfect*, but the overall message of the local distribution grids being overwhelmed is still true.
At least in Pacific Gas and Electric territory the Off Peak hours are a little more generous. Off Peak starts at 9:00 pm and continues to 10:00 am.
Since we're talking about what will happen in the future, remember that the whole peak/off peak stuff isn't set in stone. The whole point is to shift usage to the time when the power is available, but if that becomes counterproductive, they'll change the incentive. Smart-grid directed charge times are clearly the answer here. With the Model S 90% of the time I don't even need to charge every day, and my car sits in the garage for for at 15 hours between driving, where I only need to charge for 2-3 of those hours. I feel like this conversation veers towards what would happen if tomorrow everybody went out and bought an EV, rather than what needs to change to accommodate increasing EV usage over the next 10 years.
That's PG&E's E-6 TOU plan, for solar customers. For EV customers, PG&E offers E-6, E-9, and is transitioning E-9 to their new EV plan. Both E-9 and EV off peak are midnight to 7:00 am. E-9 has substantially lower cost off peak rates than E-6. EV has a similar base rate for off peak as E-6, but unlike E-6 there are no tiers for higher than base usage in the EV plan.
Norbert
TSLA will win
+1. Until EVs are more than 60% of the fleet (as opposed to 60% of new cars sold), it might even take more than 20 years.
Right, but with solar E-6 is likely the best plan. What are the off peak rates for the new plan?
Here's PG&E's rate plans
Pacific Gas & Electric - Tariffs
Rate Options
The summer off peak rate for E-9a is $0.03855/kWh at Tier 1, which is less than E-6 at $010074/kWh. However it appears that PG&E does not allow customers to sign up for E-9a or E-9b anymore. They replaced those with EV-A and EV-B, which have higher rates than E-9a and E-9b at Tier 1. But EV-A and EV-B have no tiers.
A TMC member developed a tool for analyzing detailed electric usage to compare PG&E TOU plans. YMMV. It's complicated to compare PG&E's TOU plans because they have different time periods for off peak, partial peak, and peak in addition to differences like seasonal rates, tiers vs. no tiers, etc. And solar production varies seasonally, which adds to the complexity of the comparison.
PGE downloaded data
For comparison, I had a talk with the consumer liaison for APC at our AZ house a short while back, asking her about upping our facility from a 400amp. She said we could go to a 600amp without increasing the 50kVA transformer, but if we jumped to 800A they would have to resize the transformer to a 75kVA, and that would be on my $3,000 or so dime (pricey dime!).
I think I have all those numbers right, but as f(my dear wife), my back-of-envelope scribbles tend to have short half lives
For comparison, I had a talk with the consumer liaison for APC at our AZ house a short while back, asking her about upping our facility from a 400amp. She said we could go to a 600amp without increasing the 50kVA transformer, but if we jumped to 800A they would have to resize the transformer to a 75kVA, and that would be on my $3,000 or so dime (pricey dime!).
I think I have all those numbers right, but as f(my dear wife), my back-of-envelope scribbles tend to have short half lives
That sounds reasonable. They're going to look at your usage (or planned usage) and make a determination based on that and other typical installations, as well as considering what state requirements force them to do.
I think I have all those numbers right, but as f(my dear wife), my back-of-envelope scribbles tend to have short half lives
Yeah, I know....
Cottonwood
Roadster#433, Model S#S37
When I did my upgrade in Pagosa Springs with La Plata Electric Association, I would have had to pay for the transformer upgrade, except for the fact that I was adding to the square footage of the house which would use more, TOU, ETS heat, I converted a propane hot water heater to a TOU, super-insulated electric hot water heater, and added another TOU hot water heater to the addition. Some combination of these details, or perhaps all of them combined put me in the FREE upgrade category.
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