You can skip the "stream it back at night" part. If you have a big battery, you don't need to charge it to full every day. So you plug in day and night, and have an algorithm pick when it actually charges... based on the wind/sun forecast and your calendar entries.

Then there is no extra battery wear.

There are quite a few people here in Palo Alto who can plug in at work. Facebook has more than 100 chargers at their HQ, and half of the EVs at my apartment complex never use our free charger.

A company I worked with looked into this model. The problem is that most cars are not in garages near PV during the day, they're in parking lots at work or in shopping/errand locations. They return to garages and plug in just before sunset, so the load on the grid from EVs actually goes up right as the input from PV is going down.

The model does work great with powerwall-type devices, though.

But if you offer to pay people who keep their cars plugged in during the day, probably more people would do it. Also, while car batteries are likely to be lower in the evenings, they're probably not completely dead. They could feed the remaining energy back to the grid at that time, then charge up later at night when the load is lower.

1) The percentage of people with EVs who leave them plugged in at home during the day is very small. This is unlikely to change for several years.

2) It's a bad proposition to people because you're basically telling them they won't be able to take long trips in the morning and you're going to decrease the life of their battery (people are rightfully really concerned about this).

3) The big concern with utilities right now is how to handle home renewable excess power during the day. All the rooftop PV is feeding a bunch of power back into the grid when it's sunny, then all those homes are sucking down power from dusk to dawn. The utilities need daytime power storage or non-daylight generation to offset this. Storing power at night doesn't do much to actually solve the problem, so there's not much of a business model in it. Grid-scale battery installations are quickly becoming the solution here.

If you're looking for a car-based model that could potentially work for this, it has to involve solar parking lots and also be car-specific. Charge your car at a parking lot during the day, drive it home and plug it in to power your house in the evening. Get a discount from your electric company as a result.

I sorta get the idea but who wants to burn cycles on your EV to save a couple of bucks a month? It makes no sense to me.

You can just buy batteries for your house. We’re down to what? $200/kWh? Less? If there wasn’t so much mark up in the industry, you could buy a whole house battery for 2-3k that would be good enough to shift most of your energy usage. Utilities just need to incentivize it, which presumably would happen naturally due to market forces as solar adoption goes up.

What stops the cars being charged at the parking lot at work or shopping/errand locations? One could imagine a distributed model where you have a small battery home and you not only shop your groceries but also the electricity and bring that home with your car. (Likely not relevant model in densely populated areas)

In that scenario, the parking lots need to be on the grid. Even if you cover a car in solar panels, for almost everyone they’d be a range booster rather than turn the car into a net producer.

> In that scenario, the parking lots need to be on the grid.

Not necessarily. You can imagine a grocery store covering the roof of their building in solar panels to run chargers in the parking lot. If solar gets cheap enough they might even do it for free (or below market rates) to drive business to the store. Then you charge up your car while shopping, use the power at night.

Even that won’t be enough. At least, that’s what I remember from https://withouthotair.com/c6/page_42.shtml

Don’t get me wrong, I’m optimistic about replacing fossil fuels and think things are already better than McKay dared to hope for, but I think a grid has to be part of the solution.

Grid is also useful for time shifting power demand/production to smooth out the morning/evening dips, for space-shifting production to deal with clouds etc., and (assuming wind is part of the solution) the best wind resources aren’t where you actually want to build houses.

> Even that won’t be enough.

It looks like you're right that just covering the store and parking lot in panels wouldn't be enough. But then you've got two possibilities. One is the store is in the city, and then it can be on the grid, because there is always going to be a grid in the city. The other is the store isn't in the city and then you've got cheap land next to the store to fill with panels and turbines.

> Grid is also useful for time shifting power demand/production to smooth out the morning/evening dips, for space-shifting production to deal with clouds etc., and (assuming wind is part of the solution) the best wind resources aren’t where you actually want to build houses.

But batteries (especially when they're in cars) do the same thing. Your house may not be on the grid, but it's got panels on it that power it during the day, meanwhile your car is out getting charged up somewhere else, and you use that power at night.

Electric car typically has a >50kWh battery, which will power a typical household for about two days on its own, call it twice that if the house runs on its own panels during the day. So as long as you get the equivalent of a full charge twice a week, that's all you need, right?

Your home can run for two days from an EV battery, but the problem isn’t the home, it’s the car itself.

http://www.withouthotair.com/c18/page_103.shtml

I’m not saying what you propose can’t be done — and perhaps American cities are different enough from Europeans cities that it makes sense to treat each one as an island grid in a way you wouldn’t want to around here — just that the grid still looks useful to me.

Actually, thinking about what I saw in California and Nevada when I visited, I can easily believe American cities “should” be independent electrical islands once we get enough worldwide battery production.

> Your home can run for two days from an EV battery, but the problem isn’t the home, it’s the car itself.

Those numbers seem high for electric vehicles. You've got a Model 3 doing something like 26kWh per 100 miles and an average commute of 16 miles each way. That's less than 10kWh per day but they're showing 40.

At what point does switching to something more trolleybus like, where your car charges while driving down the road, maybe in contact with a rail, make more sense than all this self driving and battery capacity? Even if it was just interstates.

Likely never (if you look at Tesla's luxury vehicles almost at 400 miles of range [S and X with Raven drivetrains] and their Supercharger charge rates [0-80% SOC in ~15-20 minutes]). Battery capacity per kg and charge rates are likely to improve faster than coordinating the deployment of nationwide rail or overhead wire electrical infrastructure on interstates (a Supercharger station only takes about two weeks to install, and costs ~$150k-200k).

https://supercharge.info/map

I'm still hoping that Teslas on AP will eventually begin to coordinate and drive very close together or even attach bumper-to-bumper in order to save energy on highways due to lower air resistance. Ad hoc highway trains more or less...

For all practical purposes they have that now. The CD on tesla cars is very low, and even AP1 cars will follow other vehicles on the highway for hundreds of miles without a hitch.

The AP follow distance setting can be set from 1 to 7, and setting it to 1 just ends up with more abrupt braking when traffic encounters a slowdown. A spaced out setting of 4 is a much more comfortable setting.

If the cars were able to push and pull each other, engines/batteries could be used optimally. Cars with nearly empty batteries would recuperate and recharge if absolutely needed, cars with full batteries would pull the rest. AP would put the most suitable car in front to minimize the total air resistance... Lots of possibilities.

Might be worth designing a new type of car for this kind of use though.

Yes, but energy density is terrible. You are having to move 3x the weight not to mention the huge effincicy hit . You arent taking reality into account.

The Model 3 weighs hundreds of lb more than its equivalent in an ICE car, not 3x as much. These numbers are still improving as well.

I dont think the comparison is to ICE but to a car on a rail/line that doesnt need to carry its energy at all (or only a small battery for the last 30 miles.)

That is an unreasonable comparison to make, considering EVs are competing with ICE vehicles, not trains or busses.

But this is a tangent about rails and wires vs EV, not ICE.

It's a tangent about how to power personal vehicles, which are overwhelmingly powered by the gasoline.

Is that just path dependence, or maybe there are advantages to having lots of built in range?

The economics do not make sense. There are massive capital and operational expenditures to build power rails/overhead wires everywhere.

If you want to longbets.org this I will have someone put down $1000 this will not happen in any city of over 10k people in the United States in the next 20 years.

BMW 3 series: 3,582 to 3,764 lbs

Model 3: 3,627 to 4,072 lbs

At best the Tesla is 8% heavier (total weight).

Even buses are using batteries to move away from the trolley bus model. Maintaining those overhead lines is a pain, and they go offline all the time. I expect these will just go away outside of true rail usage.

EV car batteries are too expensive and overdesigned to be used for grid power (imho)

How so? We have two long range Model 3s which have 140+ kWh capacity in total (70kWh/car, conservatively). Even if you'd only allow 50% of that to be used for powering one's house (you don't want to run large batteries all the way down, or charge them to 100%, often, if you care about long-term capacity), each car could provide 35 kWh, or the equivalent capacity of ~3 PowerWalls. The proper electrical interfaces and monitoring needs to be engineered, but there isn't any good reason not to do this. Seems like such a waste. Even if you could only use 20kWh, that's still be a huge win. In states such as Florida (and, now, California) where power outages are frequent, this would be a godsend.

Of course. Drain your car during the outage, get stuck with dead car when it turns out this outage is caused by the fire nearby.