Biggest problem I guess will be expanding the charger network, simply due to physics.
On the country side, laying cables for 1MW peak load (4 superchargers @ 250 kW) will be expensive - the grid in rural areas is enough for some farms and small villages, that's it.
In cities, electric-car chargers will have to deal with political obstacles (no one wants to sacrifice free-for-all parking spots!), in addition to the electricity problem - while in a city there might be more available 10+ kV lines (you don't want to do 250 kW over 230V AC, it's over 1k A current!), sidewalks are often enough very slim as it is and it will be difficult to get a charging station installed there, and digging in earth filled with cables is not exactly fun either (been there, done that, it's manual work of the worst kind as you can't even use a proper showel...). Getting chargers in garages will face obstacles of the HOAs, plus the house uplinks usually are without much reserves - my 12-apartment house, for example, is linked to the grid on 3x63A with each apartment (~60 m2) being fed by a single 40A phase. Not much, certainly not enough to feed even two electric cars in the backyard.
Either way you'l have to rebuild the entire grid more sooner than later if electric cars should have a future... there's not enough money to rebuild Detroit's water, where should the money for a full scale grid rebuild come from? It's all decades old infrastructure, no matter if in the US or Germany. Replacing or significantly upgrading it means billions to trillions of dollars.
Electric cars have the potential to be a key part of the solution to load management on a fully renewable grid.
The vast majority of people will usually charge overnight and don't need to regularly charge at peak times. Through intelligent charger management, you can distribute the load of charging across the entire off-peak period. The UX for this can be fairly straightforward - by default you charge at the cheapest rate, or you can press a button to get the quickest possible charge.
The real dividend comes from bidirectional charging, using the collective resources of plugged-in cars as a load balancing reservoir. In exchange for a discount on your electricity, the grid can take a small percentage of your EV's battery capacity when needed. A typical mid-range electric car has a 40kWh battery, which represents about four days of electricity consumption for a typical European household.
Nissan and the British utility regulator ran a two-year trial to examine the long-term impact of EVs on local grid infrastructure. The trial used intelligently-managed unidirectional charging. They concluded that about 32% of local electricity circuits will need to be upgraded by the time that EVs represent a majority of vehicles on the road. This figure could potentially be lowered further by bidirectional charging technology.
America still has huge potential for efficiency savings, because of the immensely high average household electricity consumption. The average American household uses nearly three times as much electricity as the average European household. Air conditioning is only a small part of this disparity, representing about 18% of the electricity consumption of American households according to the Energy Information Administration.
Currently utilities buy power during peak times from other utilities, or fire up expensive peaker generators to manage the load.
A network of charging cars could be managed as another resource with a price attached to it that may be cheaper than the alternatives. I like the concept of varying the price of the charge based on your participation in the network.
At least in Florida, USA, most residential electric meters are flat-rate (same price per KWh, no matter what time of day you are using). A good portion of commercial meters have a peak and off-peak rate, as well as a single line item charge, based on peak demand, that is often 30-40% of the entire bill. The off-peak rate is often 50% or more cheaper than the peak rate.
Since most people would charge at night, it would probably make sense to have these residential services switched to a demand and time-of-day based meter, which would further reduce the cost of electricity. If someone spends a significant time at home, the charging car could buffer peak loads during the day to offset the additional draw of the nighttime charging.
This sounds great and sensible in a hand-wavy way, but getting the technology in place to effectively use plugged-in EVs for extra peak load capacity will take a long time. This sort of thing was never thought about in grid design engineering until very recently.
Also think about when peak demand happens -- late afternoon on hot summer days. Right at the time when people are getting home, with their EVs discharged (or at least, not at full capacity) after a day's use.
Vehicle-to-grid technology is already being piloted in the UK and will be available to consumers in Q2/Q3 2018. There is an industry-wide roadmap for the development of local electricity markets with real-time pricing. Any customer can choose to have a smart meter installed free of charge; the goal is to have full deployment of smart metering by 2020. These meters use Zigbee to provide real-time consumption data to a wireless display unit. With future firmware upgrades, they will be capable of providing real-time pricing information to smart appliances.
The grid is already perfectly capable of consumer feed-in, hence the huge deployment of photovoltaic solar systems. The metering is not particularly difficult. There is an emerging standard for smart grid communications (LTE on the 450MHz band) that is already in widespread use across the EU.
Completing this transition won't be cheap, but there are no significant roadblocks. We know what needs to be done and we have the technology to do it.
> Also think about when peak demand happens -- late afternoon on hot summer days. Right at the time when people are getting home, with their EVs discharged (or at least, not at full capacity) after a day's use.
Not completely discharged - the little available per car will add up to a lot when there are a lot of EVs. The EV owners who decide to sell to the grid at peak hours (at higher prices) might make a profit doing so.
Even if the expensive infrastructure was put in place to allow electric car batteries to be used as a peak load reservoir, utilities would still need to maintain traditional on demand resources, such as natural gas fired power plants. Using a large number of cars is not dependable, utilities need on demand dependability.
What happens if during peak consumption in the evening winter months more people stay out late (such as on New Years Eve) and most people park in places where there's no way to plug in?
This would only add to overall infrastructure costs, adding a huge bidirectional grid in addition to traditional power sources that must be maintained year round for on demand use.
Long story short: NRG wanted to build a natural gas peaker plant, California Energy Commission said "can you do this cost-effectively with storage?", NRG said no, then people realized the "no" was based on 4-year-old battery figures. With updated figures (storage follows a manufacturing curve where the more we build the cheaper it becomes, so prices are dropping every year just as they've done with solar), turns out that yes, storage is a potentially cost-competitive alternative to nat gas peakers.
The application to build the plant is on hold to let the battery folks submit a few bids, I believe, but the econmic trends are clear: you can do peaker plants with storage now (or at least very soon).
It's just a matter of safety margins and probability. Traditional powerplants break too, and with enough cars the probability that enough of them wouldn't be available at once is smaller than the probability that enough powerplants break at once.
There is so much work and planning that goes on between the utilities and regulatory agencies to ensure we almost always have reliable electrical supply. Traditional plants have planned outages for regular maintenance, and they are constantly working to ensure there are enough backup systems and alternate routes to ensure there are not outages even during maintenance windows. The amount of cars and the amount of extra grid you would have to build to completely replace these traditional plants would be prohibitively expensive. It's not just a matter of plugging a few million cars into homes.
A potential issue I see with this is the fact that some people need to get to and from work during hours that would prohibit them from charging at off-peak hours. Night-shift jobs tend to be on the lower end of the pay scale (though there may be a bonus for taking that awful shift compared to their day-time peers.) So there is an opportunity for some regressiveness in this scheme.
As we move towards renewable generation, the shape of the peak and off-peak periods will start to change. In the southern states, you might see very flat pricing, as higher consumption during the day is offset by higher generation from photovoltaic sources.
We will see far more volatile supply, because of the less reliable output of renewable sources. Supply and demand need to be perfectly balanced at all times to prevent brownouts or outages. Balancing supply and demand will become more challenging as we start to take fossil fuel generators offline. This is where smart grid management becomes vital.
EVs could adjust their charging rate in real-time, drawing maximum current when prices are low and discharging at a high rate when prices spike. Smart air conditioning units and refrigerators could respond to pricing on a minute-by-minute basis, running their compressors when electricity is a fraction of a cent cheaper and allowing the temperature to drift upwards by a fraction of a degree when prices are slightly higher. Industrial consumers could pause energy-intensive processes when prices are high and store power locally in battery, pumped water or thermal storage when prices are low.
A slightly extreme example from the UK is the notorious TV pickup. We drink lots of tea and use 3kW electric kettles to make it. During the commercial break in popular TV programmes, there's a surge in demand that often reaches hundreds of megawatts as millions of people simultaneously switch their kettles on. The national grid employ a dedicated team to manage these rapid demand spikes. They study the TV schedules and continuously monitor the grid frequency, turning on extra generation capacity and drawing from pumped-water storage to balance the extra demand. With smart grid technology, the TV pickup could be automatically managed through a real-time market.
I was talking to a professor of electrical engineering who performs research on the electric grid. She said that while in theory it is possible to configure cars to charge themselves when electricity is cheapest, currently residential utility plans don’t adjust pricing based on time of day. Your electricity bill’s tiers are based on your total consumption.
Edit: lol, I get downvoted for relaying what a professor of EE told me. Stay classy HN.
TOU (Time of Use) rates are becoming more and more common.
In 2019, TOU rates will be the default rate structure for new accounts in California. Many more states are following suite.
Even if they're not the default, tons of places have opt-in TOU structures. EV owners and home storage owners use this a lot.
Some states have even already adopted complicated shit only seen in C&I customers: demand charges. Basically, a portion of your bill will be dependent on your peak demand during a period (ie peak kW, not total kWh).
Here (in Estonia) the pricing changes every full hour. We get pricing for the next day (24h) a day before by 14 (2 pm). This is calculated from weather forecast, expected consumption and available generation resources. This is for residential use. For industrial applications you can buy electrical energy from the grid based on 15 minute pricing slots. Almost all the houses are equiped with online readable power meters.
I think this is the way things are moving in other jurisdictiins as well. In case of Germany and France one of the reasons why the systems have mot been upgraded lies in the privacy rules for the power consumption data according to one smart meter manufacturer.
> In case of Germany and France one of the reasons why the systems have mot been upgraded lies in the privacy rules for the power consumption data according to one smart meter manufacturer.
Not just that, in addition the smart meters cost a bunch of money to install... people don't like paying anything very much.
Norway is going all-in on smart meters, installation has been rolled out this year to ~80% of the country, due to reach 100% next year. The total installation cost is estimated at around 2.5 billion USD for around 2.2 mill. houses, i.e $1000 per house. Which of course we as consumers will be paying for through higher electricity prices.
When I lived in New York State in the mid 1990s, there was time-variable electricity pricing. Being a grad student, I exploited it to do my dishes and clothes after peak hours to save money. Eventually I put my water heater on a timer. I think the rate differential was significant (order of $.07/kWh vs. $.11/kWh).
This professor has no idea what they're talking about. Every energy supplier I know of in my area offers an off peak discount specifically tailored to electric vehicles.
That depends on the country. In Germany the only discounts I know are for people using electric central heaters which heat up over night (Nachtspeicherofen).
Something as modern as time-variable tariffs... not gonna happen soon here.
Definitely not the case in California. Everyone is on a smartmeter now, and adding an electric car charger will both give you a $500 rebate and put you on variable pricing.
Tesla has already started incorporating stationary storage into some of its supercharger stations to help cut down on peak load. This is not just an act of goodwill, it actually makes economic sense for them, since it cuts down on demand charges from the utilities for high peak loads, as well as reducing the need for bigger transformers and such leading up to the station.
The electrical grid is already sized for peak usage, not average usage. Supercharger stations are also being sized for peak usage, and most of the stalls usually remain empty. Incorporating stationary storage cuts down on the costs incurred by both of these inefficiencies.
> Incorporating stationary storage cuts down on the costs incurred by both of these inefficiencies.
at the cost of 10% more power usage due to the inefficiencies of charging and discharging batteries. Might still be worth it from an electric company's bottom line, but in most markets, it increases greenhouse gas production because we need more kwh of power.
If charging happens at the place where the car spends most of its time, then even domestic 16A/230V sockets would be enough for typical usage (for atypical usage, there are superchargers).
Exactly, charging is greater than 10mph at 16A (typical dryer load). If you drive 40mi (1hr commute?) each way and only charge at home, you can charge in the 8 hours between 11pm and 7am.
Yeah but the load peak when everyone arrives home/at work is what's dangerous for the grid. Even 10k cars at only 10 kW of charging power are a peak load of 100 MW. 100k cars are 1GW - which means the city of Munich with 700k cars has a load potential of 7GW at the minimum.
Either we get a grid that's intelligent enough to balance stuff out or the grid has to be built out with massive reserves, and that's everything but not cheap.
How does this work in practice, with a high number of cars with such apps? Say everyone arrives home from commute at roughly the same time, how is the delay factor decided/distributed?
In the most interesting fantasy, the car has an idea of how much it actually needs to charge -- Bolts and Teslas often don't use but a small fraction of their battery on a typical day -- and the grid has an idea of how much wind energy it's going to get in the middle of the night. And you'd combine the two to make sure all of the wind energy gets put into a car battery, or car batteries don't end up full because the owners don't need it tomorrow and the wind is expected to be strong tomorrow evening.
You can do the same solar energy and cars plugged in during the daytime, soaking up excess solar electric generation.
In terms of rural areas, this will be an interesting challenge. When you drive cross country in the USA, you can expect to find gasoline reasonably close to even the most remote areas. The distance to the next gas station from anywhere in the USA is well below the range of the typical car.
However, in regards to cities, you are presenting a situation where the charging station comes to the parked car, rather than the car going to the charging station. While that would be quite convenient, if the charging times are rapidly decreased, there’s no reason car owners in cities would not be able to drive to stations to charge up, as drivers do with gas stations today.
Charging times have an upper bound: physics. 250 kW is an insane amount of power and still you'd need around half an hour to fill a 100 kWh battery, to get even close to the 5-10 minutes of charging like at a gas station you'd need megawatts of peak power... and as there are two steps of conversions involved (grid => HVDC => battery voltage), even with 99% efficiency you have 1% (or 10 kW) of heat loss alone. That heat in the small space of a battery pack is a challenge.
So this is not a perfect comparison but potentially a useful one.
Gasoline has about 33kWh per gallon. A typical gas pump is limited to 10 gal/min flow rate (lets say 8gpm just to be conservative).
That means your gas pump takes about a minute to dispense 250 kWh or 23 seconds to dispense 100kWh. That generates effectively no heat. To charge one electric vehicle at the equivalent rate (assuming it could tolerate it) would take a 15 megawatt power source per 'pump'.
Here is the size of a one megawatt AC to DC power substation:
"The complete ABB megawatt station
weighs only 20 tons. At 50 m3, the
container’s volume is some 15 percent
smaller than equivalent solutions."
I own an EV (hybrid really, Volt, but I'm 85% electric). I support electric vehicles enormously. But this is a huge huge problem with scaling that no one talks about. My volt can charge, slowly, at 8 amps (~1kW) while I'm at home, a rate my home power can easily take. Most vehicles in the US are static for at least 8 hours once, if not twice, during the day. Using that time to charge slower is a stopgap but I really doubt that the US grid has the excess capacity for this.
Have you thought of putting solar on your roof with storage to collect the extra energy you produce during the day and then dump it into your car at night?
Yeah, there are efficiency losses along the way, but two points:
- More and more net metering tariffs are homeowner-buys-at-retail-pricing-grid-purchases-back-at-wholesale-pricing... the homeowner value of solar's excess energy is getting less
- In a lot of cheaper EV purchases, the car company still owns the battery packs. This is for two reasons: 1) They sell you on a new battery pack when your range starts to decline after a few years, and 2) They're going to use the degraded batteries as second-life storage products... maybe not good enough to power your car, but more than plenty to provide a cheap powerwall alternative.
The points you bring up about mass charging is true, but once pricing starts to reflect that, that's going to make home storage far more economical (it already makes economic sense in some markets).
If the range is enough, stopping to charge up for 30 mins means one can also grab a bite to eat.
My parents took us kids on car trips during summer holidays, and usually by the time we needed to stop to refuel the car we also took the time to eat and such.
A problem is not everyone wants to wait half an hour for every charge on a long distance trip. If I'm driving 12 hours, I want to get to my destination with minimal interruption. Having to wait 30+ minutes for each of the 2+ refuelings would be a pain and add a considerable amount of time to the already lengthy trip. I'd avoid that pain point if that's the choice.
I make about 4 trips like that a year. While it is certainly not a regular occurrence it is frequent enough that I would take it into consideration when looking at a vehicle. The point is not that I use the full range of my vehicle all of the time, but that I have the capability to due so. Don't get me wrong. I'm very interested in electric cars. However, the current ranges (which are close to being up to par), and especially the lack of infrastructure and long refueling times dissuades me from actually looking into purchasing one.
I believe our supercharge yesterday gave us 50kwh in 25 minutes.
I'm not disputing your point. It's a HELL of a lot more juice than people are used to thinking on a day to day basis. And it's going to change our infrastructure in fundamental ways.
Is there really a HVDC to battery voltage conversion step? I thought the whole point of quick charging is that you get exactly the DC that the battery needs right from the charger.
Actually, the superchargers take AC from the grid. The equipment at the supercharger consists of a rack of AC to DC converters run in parallel. That creates the DC that is delivered to the batteries at about 400 Volts.
As far as I understand, the car asks the Level 3 charger for a certain amount of volts and amperes, and the charger delivers exactly what the car needs (being able to vary the parameters for each type of car - and yes, those Level 3 DC chargers are big, complex, and expensive). Then the current goes directly to the battery. And this is why the charging gets so fast: there are no intermediate steps. The car just needs to provide cooling for the battery and control the charging process.
You're both right. A Level 3 charger does deliver the right DC voltage the car needs, and it does so using power electronics that convert regular old grid AC into DC.
Level 1 & Level 2 charging: AC grid -> cable -> onboard charger converts to 400V DC -> battery
Level 3 charging: AC grid -> offboard charger converts to 400V DC -> cable -> battery
Same number of steps, same conversion efficiency. Tesla even goes a step further and uses the same hardware, building out the (low volume) Superchargers "simply" by ganging together a dozen (high volume) on-board charger modules and stacking them inside a weatherized outdoor cabinet. This commonality maximizes their economies of scale.
Wouldn't there be an additional stepping at the transformer for level 1 and 2 chargers to go from AC distribution grid at 480V AC to 110V/220V where the level 3 superchargers can plug directly into the 480V AC mains without a transformer?
For anyone that's confused, it's because now we're really getting into the weeds of how the grid works. :) It's only fair to look back and compare from the same point in the grid, in order to be an apples to apples comparison. Really we should look at the whole electricity supply chain.
Level 1 & 2 charging: high voltage AC transmission line -> local substation converts to 480V AC -> distribution lines (poles or buried) -> pole-mounted or buried transformer converts to 110/220V AC -> household wiring -> cable -> onboard charger converts to 400V DC -> battery
Level 3 charging: high voltage AC transmission line -> on-site transformer converts to 480V AC -> offboard charger converts to 400V DC -> cable -> battery
But that replacement doesn't need to happen quickly, cars won't get replaced sooner well... than the cars are replaced, which is, about once in 15 years. Even if market share of electric cars in dealerships is 100%. So grid requirements will evolve slowly through about 2050, not overnight - which is hardly faster than its normal renewal rate.
In my neighborhood there has been no electrical grid upgrade (other than repairs) since the 1960s (when the subdivision was built). I think your 15 year timeline for normal grid renewal is wildly optimistic at least for most established suburban areas.
Also few people keep their cars for 15 years. I think 5-7 years is much more normal (though perhaps you meant the total life of the car, from original owner to the last).
Personally, I keep cars until they're no longer reliable/economical but the average length of ownership is presumably lower and brought down by people who get a new car after a 3 year lease. Although the overall length of ownership has been increasing because of improved quality.
Given the trend (in Germany) to crack down on ICE cars, you're looking at a way shorter timeframe. Once the first court OKs ICE bans, stuff is going to get nasty.
The UK grid company (who also run some of the US grid) put out a report on the impact which I'll summarise as "no big deal". They mapped out a few different scenarios, the most extreme of which got taken, then mangled and exagerrated and turned into scary headlines about EVs destroying the grid.
They then had to issue a second report pointing out that their first report said it wasn't going to be a big deal.
> The USA installed Cable TV, why would charging cables be harder?
Because a TV coax cable is 1cm slim and can be installed very easily. Run it over the air on poles, dig it into a small trench, run it via the sewers. Whatever fits best.
A 10 kV or, worse, a 1 kA-capable 3x230V line, not so much. The 10kV (or more) line has special requirements in terms of distance to other cables, a 3x230V line at that capability is pure hell due to its sheer thickness and mass.
Also the charger station will require a transformer... which aren't tiny, and transforming 250kW produces significant heat loss. So either find some free place in earth where you can bury it, or deal with adjacent house owners to install the transformer in their basement.
> The USA spends $500Billion on cars and $400 Billion on gasoline every year. A onetime $trillon upgrade isn't an outsize amount.
Problem is, the car/gasoline spend is done by individuals on small-ish scales. A multi-trillion investment must be fronted by the state - the utility companies don't have nearly enough cash to finance this. But, as noted, the US can't get enough funds to replace Flint's potable water infrastructure or Puerto Rico's broken grid...
And it took many years and is still not universally available. (About 70% broadband penetration seems to be the current number although it may be available to some of the other 30% but just not bought.)
An electric car is at least a $20k investment. If you're buying a $20k car $2k of electrical upgrades are certainly a factor in the purchasing decision, but you can at least afford to upgrade your house and work parking. And realistically the cost is likely to be lower than that, and even not it pays off in lowered fuel costs.
Tesla has only added a few chargers though, and they carefully selected the locations to be places where there are newer upgraded power lines. If electric cars become common chargers will need to be everywhere including older neighborhoods where the power lines are not up to the load.
Yes, and standard chargers can be installed anywhere you can put a clothes dryer. You only need 120kW charging if you're going to be road-tripping. In the 2+ years I've owned an EV I've never had an issue, including doing 300mi+ in a single day about once a week.
Heck, when I bought my current house I didn't need to do anything since the previous owner already had a NEMA 14-50 outlet for their welder.
Yeah it's all so simple until you realize that means every house running a clothes dryer all at the same time between 5pm and whatever time in the evening everyone is done charging.
Los Angeles and parts of the Bay Area have had nearly annual brownouts for the last 20 years just from air conditioners during heat waves. How in the world do you expect that aging power grid (in the fifth/sixth largest economy no less...) to handle a clothes dryers in every house running 4+ hours a day?
Fortunately those "clothes dryers" are already connected to the internet, and have sophisticated power electronics hooked to the grid that can detect voltage sag and phase lag. Connected to a central server, each car (or stationary battery, for that matter) becomes BOTH a sensor that can monitor grid health AND a remote-control load that can be dialed up and down (so long as the car gets a full charge before 7am, or whenever the user chooses).
The internet allows entire neighborhoods of EVs to be controlled at once, so that the substation is at 100% power and no more, and so the distribution/transmission lines are at 100% power and no more.
Is that a hard control problem? Sure. BUT it's easier than overbuilding the electric grid by 2-3x (which is, after all, the largest machine ever built[1]). And given the very large opportunity cost, there's a lot of incentive to solve it.
Most people get off work between 4 and 6pm. (this is not 50% of the population, but it is still a large number). They all go home and plug their car in then take a shower. Many days the peak electric use for the day is at 6pm when all those people start cooking dinner (electric stove) or jump in the shower (electric water heater). When a significant number of people start plugging their car in when they get home the peak will go up much more.
Of course as has been pointed out repeatedly a smart charger can manage exactly when the battery starts to charge. However it isn't quite that simple: many of those people will go out again for their bowling league or whatever, and need enough charge in their car.
You know, it is funny that I have heard so many strange hypothetical against the future of electric cars that are contradicted by the current implementation of them. Its really strange.
Many Americans are really attached to the vision of hopping in their personal vehicle with no additional transaction friction and going on long road trips.
EV charging infrastructure isn’t yet well suited to medium to long road trips, so some people discard the whole idea because they’re upset by suggesting a different distribution of friction in their lives.
Whether the actual friction is big enough to matter is hard to say. I drive outside a 100 mile radius about twice a year, and I don’t mind renting cars when I do, so it doesn’t seem especially onerous to me, but don’t underestimate people’s love for their particular car/dislike of rental cars.
It's not so much dislike at rental cars--I rent them regularly when I fly someplace--it's that they're a hassle. In my largely Uber and Lyft-less area, there are a couple of rental car places that are only open during regular business hours. So renting a car for the weekend (very possibly a time when others are renting as well) would involve taking a taxi there before they close on Friday and dropping it off on Monday morning. That's a huge hassle for something I do at least every month so it's not a vision; it's something that I do on a regular basis.
As with all technological transitions, some municipalities will see the writing on the wall and invest. Others will not, and will see their local economy contract and young people flee.
“The grid to your home can’t even provide enough power to charge your car” becomes a decent reason not to move there.
Parts of the USA. Eagle Mountain, UT has a population of 30,000 and no cable TV. It is just down the road from the NSA building, it isn't like it is in the middle of nowhere. There wasn't much there in 1999. For a city that is very young - nobody wanted to put up money for cable.
I'm almost sure the county I live in now doesn't have cable TV anywhere. It costs a lot to roll out a network of anything. I'd guess a power network costs more than cable or fiber.
That's interesting. Cheap 15% efficient solar panel produces 0.75 kWh per square meter per day in "average US location" [1], whatever that is.
Let's assume average parking space area is 10 square meters (it depends, but it's close [2]) - so that's 7.5 kWh per day.
Average energy consumption of electric cars is 11-16 kWh/100 km [3], let's assume 10 kWh/100 km - that's 75 km range for a day of standing in sun.
That's actually not bad, and should be enough for driving back home from work. Actually, why not just put the solar cells on the car and do away with the batteries (car already has them). It would be less area, but even 20 km of driving for free would be enough for many people.
Hell, I use a car maybe twice a week, usually to drive for less than 10 km. Such a car would basically drive for free for my use case :)
Actually, why not just put the solar cells on the car and do away with the batteries
Because you might squeeze 200W worth of panels up there at best. On a sunny day you’ll get about 4 extra miles at the end of your workday. And now you can’t drive home with the sunroof open on that sunny day.
For reasonable cost you can get 22.5% panels. A Camry is 193 inch x 72 inch or ~9 square meters. However, you don't get to tilt the panels and need to deal with shade, but can add cells to the sides which helps though at lower efficiency. Still ~6 hours of full sun equivalent x 9 * 0.225 ~= 12 kwh for a fairly normal shape.
Tesla Model 3 gets 310 miles on 75kwh so call it 4 miles per kwh that's 40-50 ish miles per day if you can stay in the sun.
Current records for solar panels well over 40%, so a fully solar powered car may actually be possible even if stupid expensive.
PS: Those solar challange cars are getting impressive. http://solarteameindhoven.itility.nl/ is a 4 seater doing 60+mph though far from street legal.
From a weight perspective they still add range so it's not a bad idea. Further, being able to run some fans or even AC while in full sun is a significant benefit.
Car companies are not adding panels because the benefit is not huge, they add complexity and cost, and panels negatively impact styling. Still, you see a lot of campers with solar panels on the roof because a few kwh/day of extra power really does add up over time.
Further, being able to run some fans or even AC while in full sun is a significant benefit.
You’re going to need those fans with giant, black heat sinks on your roof. To the point that I wonder if the panels heat the car faster than fans can remove it.
Still, you see a lot of campers with solar panels on the roof because a few kwh/day of extra power really does add up over time.
You see a solar panel on our VW camper because a 100W panel can easily recharge the battery that runs the 20W of LED lighting, and charge the occasional laptop, not run a 80,000W traction motor. My parents have a 35 foot fifth wheel with A/C, microwave, and other goodies. It has an option for solar panels. They didn’t buy that option because solar panels ain’t gonna do squat for that load. They figured it might buy an extra half day of boondocking before the house batteries run out. No, you see a lot of campers with solar because they either have a small load like us, or the salesman convinced them it would be a good idea on their 40 foot Class A tour bus.
Solar panels convert sunlight to energy, this means they don't heat up as much as you might think. Further, painting the outside of a car black does not heat up the inside of a car as much as you might think. Most heat gain is from sunlight hitting the inside of the car converting to IR, and then being blocked by glass. Thus, painting the inside black is a larger issue.
A 120mm computer at full speed is ~6w and can move 75 cubic feet of air per minute. So, 20w worth of fans can quickly exchange a lot of air.
Anyway, 100W of panels is minimal if your using 20+% panels. You can get that from a 1.5 foot x 3 foot section, a camper can have 20 of those on the roof assuming your starting with mostly clear space.
I agree with you that the solar panels aren't going to run the motor, but the 660W of solar on my RV with a large battery bank and a 3000W inverter have no trouble running everything in my RV including the AC for an hour here or there (though we did replace the AC with a swamp cooler to be able to run longer in the southwest): http://therecklesschoice.com/2016/04/29/diy-rv-solar/
The way I look at it, putting panels on the car is a good idea (because it reduces the need to charge frequently for people who don't drive long distances regularly) that sounds like a bad idea (because the power from panels is so much less than the power requirements of the car while it's running) that sounds like a good idea (hey, why not get energy for free!).
Not everyone will benefit or care about charging their car a few less times per year and adding panels will cost more, add weight, and probably change the appearance of the car, but I think it's an option worth exploring.
Because that energy isn’t free. Panels cost money, the electronics to get it to the batteries cost money, and increased complexity cost money. You won’t get a sunroof. Those black panels that are specifically designed to optimize the absorption of the sun’s energy will absorb heat.
All so I can get an extra four miles (on a good day) of range after sitting in the sun all day. I’m not going to go as far as to say it’s a dumb idea, but it sure is hell isnt a good one with current technology.
You’re ignoring conversion/storage losses when charging, which are on the order of 20%. And I think actual EVs are much closer to the less efficient end of your range (with the heat on, I barely get 3 miles / kWh on my Bolt, with no environmental controls, it’s about 4 miles / kWh, which is already the least efficient end of your range).
Would it be feasible to put inductive chargers and battery banks under the parking spot, so that no wires are exposed and the spot could be used by non electric cars if required? Maybe a signal to/from the car to determine charge rates and negotiate power feeds? Or is that too much power to pass through a special thin layer of say, epoxy concrete? Seems like a good place to have a battery box, to protect it from heat/rain/lightning.
Over the next 50 years if solar roofs take off ( https://www.tesla.com/solarroof ) I don't see it being that much of a problem on the country side. We probably won't need to rebuild the entire grid, may be able to leave some part of the grid behind. May even be cheaper to do so with savings compared to the alternative options
Solar roofs are just fancy solar panels. And they wont help it there is no sun.
There are two ways of making sure you still get power when there is no sun for your panels: storing power locally and using the grid. For storage, you can have enough batteries to deal with the day-night cycle, but a week of overcast weather in the winter is likely to be prohibitively expensive. It means that the grid is necessary, and it has to be able to cope with peak load.
There's also wind when these winter storms roll through :). I've found out personally that people can also adapt to new situations such as less availability of electricity.
I have an outdoor ev charger (no garage) and I've plugged it in during downpours with no issues. EV charging plugs (J1772) have recessed contacts that you can't touch without tremendous effort and electronics that ensure that they don't turn on the charging current until they are securely affixed to and communicating with the car.
There is a pilot current to establish the communication that coordinates this but it's nothing that would electrocute someone (probably similar to an Ethernet cable).
On the country side, laying cables for 1MW peak load (4 superchargers @ 250 kW) will be expensive - the grid in rural areas is enough for some farms and small villages, that's it.
In cities, electric-car chargers will have to deal with political obstacles (no one wants to sacrifice free-for-all parking spots!), in addition to the electricity problem - while in a city there might be more available 10+ kV lines (you don't want to do 250 kW over 230V AC, it's over 1k A current!), sidewalks are often enough very slim as it is and it will be difficult to get a charging station installed there, and digging in earth filled with cables is not exactly fun either (been there, done that, it's manual work of the worst kind as you can't even use a proper showel...). Getting chargers in garages will face obstacles of the HOAs, plus the house uplinks usually are without much reserves - my 12-apartment house, for example, is linked to the grid on 3x63A with each apartment (~60 m2) being fed by a single 40A phase. Not much, certainly not enough to feed even two electric cars in the backyard.
Either way you'l have to rebuild the entire grid more sooner than later if electric cars should have a future... there's not enough money to rebuild Detroit's water, where should the money for a full scale grid rebuild come from? It's all decades old infrastructure, no matter if in the US or Germany. Replacing or significantly upgrading it means billions to trillions of dollars.