Article: Why the price of charging varies from free to 59 cents/kWh, or per minute, or everywhere else in between

[bradtem]

Here's a new article I released (including gathering some comment here in TMC) on Forbes.com today.

EV Charging Costs From $0.15 Per Mile Down To Free; How Should They Price It?

The range of prices for EV charging is astonishing, because we think of energy as a product, like gasoline, but it's really a service. What do people charge and what should they charge?

www.forbes.com

 

[jjrandorin]

Here's a new article I released (including gathering some comment here in TMC) on Forbes.com today.

EV Charging Costs From $0.15 Per Mile Down To Free; How Should They Price It?

The range of prices for EV charging is astonishing, because we think of energy as a product, like gasoline, but it's really a service. What do people charge and what should they charge?

www.forbes.com

Interesting article, thanks for sharing, and also for your regular participation here as a regular member.

 

[swaltner]

Nice article. Covers a lot of the topics related to pricing on EV charging.

As you mentioned, I’m one of the people of the mindset that price doesn’t matter (much at least). I charge for free at home (solar that produces more than I can use in a year) and so, while I wish Superchargers were as cheap as they were a year or two ago, I pretty much ignore the price on the few road trips I take each year.

One possible correction is that it is my understanding that the tiering that EA does is based off how fast your vehicle CAN charge, not how fast it IS currently charging. A Porsche Taycan pays the 270 kW rate if the battery is empty and charging at 270 kW or almost full and charging at 25 kW. I’m on a Tesla and have never used these stations, just going off memory from previous discussions. I could be wrong here.

 

[bradtem]

Nice article. Covers a lot of the topics related to pricing on EV charging.

As you mentioned, I’m one of the people of the mindset that price doesn’t matter (much at least). I charge for free at home (solar that produces more than I can use in a year) and so, while I wish Superchargers were as cheap as they were a year or two ago, I pretty much ignore the price on the few road trips I take each year.

One possible correction is that it is my understanding that the tiering that EA does is based off how fast your vehicle CAN charge, not how fast it IS currently charging. A Porsche Taycan pays the 270 kW rate if the battery is empty and charging at 270 kW or almost full and charging at 25 kW. I’m on a Tesla and have never used these stations, just going off memory from previous discussions. I could be wrong here.

I don't think there is too much charging different prices to different cars at CCS stations. There are lower prices for cars who have partnered with the station operator, but higher prices? With plug to charge they know what car you have but many of the apps for using these stations don't make you say what car you have -- does ordinary CCS without plug to charge even know?

 

[swaltner]

I just checked and this is from the current contents of Pricing and Plans for EV Charging | Electrify America (emphasis is mine)

"Pricing for DC fast charging is determined by charger location, your plan, and, for per-minute locations, the maximum power level your vehicle can accept. Pricing may be subject to tax, if applicable for the location of a particular charger."

So, yes, according to Electrify America's web site, if your vehicle CAN charge at 91 kW or higher, you pay the higher per-minute rate, not the actual power level that is being used at that time. This is different from how Tesla does the tiering on Supercharger stations that charge per-minute. If Electrify America does actually charge per-minute like Tesla does, they need to reword this statement on their web site.

I state 91 kW because for the states that I found per-minute pricing listed, one rate was given for 1-90 kW and another price was at double the lower rate was given for 1-350 kW charging.

 

[RTPEV]

I just checked and this is from the current contents of Pricing and Plans for EV Charging | Electrify America (emphasis is mine)

"Pricing for DC fast charging is determined by charger location, your plan, and, for per-minute locations, the maximum power level your vehicle can accept. Pricing may be subject to tax, if applicable for the location of a particular charger."

So, yes, according to Electrify America's web site, if your vehicle CAN charge at 91 kW or higher, you pay the higher per-minute rate, not the actual power level that is being used at that time. This is different from how Tesla does the tiering on Supercharger stations that charge per-minute. If Electrify America does actually charge per-minute like Tesla does, they need to reword this statement on their web site.

I state 91 kW because for the states that I found per-minute pricing listed, one rate was given for 1-90 kW and another price was at double the lower rate was given for 1-350 kW charging.

I think an alternate interpretation of the maximum power level your vehicle can accept is the maximum power level your vehicle can accept at that time (due to whatever environmental and state of charge conditions apply), not necessarily the spec of the vehicle.

Plug-and-charge capability aside, how is the charging station going to determine what kind of vehicle you are plugging into it anyway?

I am interpreting that as simply meaning that there are different tiers for how much power your car is drawing, and nothing more.

Now there is potentially a controversy here that the wording does not address. Let's say that you pull up to a station and your car requests 150kW of power, but the station is only able to deliver 75kW. Do you get charged the 150kW rate, or the 75kW? A less ambiguous wording, which would clear up both questions would be to simply say the power level that the station delivers to your vehicle. I bet that nuance is lost on the lawyer/marketing type that wrote that statement, and/or there are legal problems with wording it that way in jurisdictions where per-kWh pricing is not legal.

 

[bradtem]

I think an alternate interpretation of the maximum power level your vehicle can accept is the maximum power level your vehicle can accept at that time (due to whatever environmental and state of charge conditions apply), not necessarily the spec of the vehicle.

Plug-and-charge capability aside, how is the charging station going to determine what kind of vehicle you are plugging into it anyway?

I am interpreting that as simply meaning that there are different tiers for how much power your car is drawing, and nothing more.

Now there is potentially a controversy here that the wording does not address. Let's say that you pull up to a station and your car requests 150kW of power, but the station is only able to deliver 75kW. Do you get charged the 150kW rate, or the 75kW? A less ambiguous wording, which would clear up both questions would be to simply say the power level that the station delivers to your vehicle. I bet that nuance is lost on the lawyer/marketing type that wrote that statement, and/or there are legal problems with wording it that way in jurisdictions where per-kWh pricing is not legal.

I agree. Of course we are mostly Tesla drivers here (though a few have CCS adapters) so we need to get a report from somebody who has actually charged and gotten a bill to see if it charges based on "capability" or actual wattage or possibly max wattage - since most cars draw max wattage within a minute of starting charging the charger could figure that out.

 

[Rocky_H]

I think an alternate interpretation of the maximum power level your vehicle can accept is the maximum power level your vehicle can accept at that time (due to whatever environmental and state of charge conditions apply), not necessarily the spec of the vehicle.

No.

One possible correction is that it is my understanding that the tiering that EA does is based off how fast your vehicle CAN charge, not how fast it IS currently charging. A Porsche Taycan pays the 270 kW rate if the battery is empty and charging at 270 kW or almost full and charging at 25 kW. I’m on a Tesla and have never used these stations, just going off memory from previous discussions. I could be wrong here.

You're not wrong. That is correct. I have seen that discussed before and how strange and idiotic it is.

so we need to get a report from somebody who has actually charged and gotten a bill to see if it charges based on "capability" or actual wattage or possibly max wattage

It has already been tested and confirmed out in the real world. It's dumb, but that is actually how it's done. I'm not sure if I can find a thread for it, but I'll check.

(EDIT)
Here we go--I found it. This was covered by @FlatSix911 in a comment from June 9, 2019:

Electrify America Fast Chargers - Huh?

Comparison of California Rates: :cool: EA no pass: $0.25/0.69/0.99 per minute Tesla Supercharger: $0.13/0.26 per minute

teslamotorsclub.com

 

[RTPEV]

No.

You're not wrong. That is correct. I have seen that discussed before and how strange and idiotic it is.

It has already been tested and confirmed out in the real world. It's dumb, but that is actually how it's done. I'm not sure if I can find a thread for it, but I'll check.

(EDIT)
Here we go--I found it. This was covered by @FlatSix911 in a comment from June 9, 2019:

Electrify America Fast Chargers - Huh?

Comparison of California Rates: :cool: EA no pass: $0.25/0.69/0.99 per minute Tesla Supercharger: $0.13/0.26 per minute

teslamotorsclub.com

According to the post you referenced, the pricing is set by the max power draw during the first minute (seconds?) of the session, not the spec of the car. So I'm not sure how my interpretation is not correct. Am I missing something?

Well okay, I guess it again boils down to how you interpret this statement (from that post):

Electrify America’s new tiered plans query the vehicle for its maximum charging power rate when the car is first connected and use that to choose the per-minute pricing tier that will be used during the full duration of charging.

My understanding is that the communications taking place between vehicle and charger are that the vehicle requests a charging current (or voltage at higher SOC). Obviously the EVSE has the ability to request information from the car (i.e. so Plug-and-charge can identify the account to bill), but do we know that the protocol supports communicating the maximum charging rate for the vehicle to the EVSE, or is EA simply using the initial requested current to determine the tier?

Even in the event that it uses the spec max charging power rather than requested charging power, I expect that with increased competition and knowledge that this policy may be updated in the future to be more fair/competitive.

 

[bradtem]

No.

You're not wrong. That is correct. I have seen that discussed before and how strange and idiotic it is.

It has already been tested and confirmed out in the real world. It's dumb, but that is actually how it's done. I'm not sure if I can find a thread for it, but I'll check.

(EDIT)
Here we go--I found it. This was covered by @FlatSix911 in a comment from June 9, 2019:

Electrify America Fast Chargers - Huh?

Comparison of California Rates: :cool: EA no pass: $0.25/0.69/0.99 per minute Tesla Supercharger: $0.13/0.26 per minute

teslamotorsclub.com

Thanks. Now EA mostly bills by kWh so this only affects some drivers. As I note in the article, for the station operator, the time you sit using their station is more expensive to them than the energy they deliver, so they are motivated to charge you the high per-minute rate.

Really what this says is, they would prefer you not try to charge over 80%, but if you do, you are going to pay for it. Which makes sense, at least if people are waiting for that station. Tesla at busy stations will re-set your max charge to 80%, but you can manually bump it up again if you really need it. Tesla could consider surcharging you if people are waiting. As a person waiting I would want that. As a person who really needs 95% for my next leg, I would not want it.

And admit it. You've been eating, and got told your car was at 80% or whatever level you actually need, and you didn't want to go move your car right now or risk idle fees, so you bumped up the charge amount. You've done it. I've done it. Not when people are in line, but it would be tempting even then, if antisocial.

Ideally we'll build a world where stations are rarely full. As long as they are going to be full, there will be some way to discourage you charging at 25kw at a station the guy waiting would take 200kw from.

 

[KzooMYP]

One comment I've seen repeatedly is that EVSE pay ToU rates plus "burst demand" rates. Supposedly even if commercial electric rates are 2-3c/kWh, when burst demand pricing is applied, the cost per kWH can exceed $1.00

This seems like a somewhat necessary evil, given the unique demands of EVSE.

If the burst demand charges put rates as expensive as $1.00/kWH, it could/should encourage onsite battery storage combined with solar canopies (or even wind). The batteries could be topped off at night with the utility providing more attractive rates, while the solar panels do what they can during the daytime to keep the batteries charged. Then through battery management software, the onsite battery storage could be "trickle charged" throughout the day to reduce these burst demand charges.

 

[bradtem]

One comment I've seen repeatedly is that EVSE pay ToU rates plus "burst demand" rates. Supposedly even if commercial electric rates are 2-3c/kWh, when burst demand pricing is applied, the cost per kWH can exceed $1.00

This seems like a somewhat necessary evil, given the unique demands of EVSE.

If the burst demand charges put rates as expensive as $1.00/kWH, it could/should encourage onsite battery storage combined with solar canopies (or even wind). The batteries could be topped off at night with the utility providing more attractive rates, while the solar panels do what they can during the daytime to keep the batteries charged. Then through battery management software, the onsite battery storage could be "trickle charged" throughout the day to reduce these burst demand charges.

Correct. There are times when the spot price on the grid is extremely high. At those times, you only want those absolutely in need of a charge to charge. Famously in Texas during the crisis it got over $9 per kWh for customers who (foolishly) agreed to pay the spot price. Most customers don't want to risk that and do contracts which pay more other times and cap the top rate. Or in the Texas case, some customers were shut off when the rate got that high.

Now, if you're sitting at a charger, out of juice and they say "this charge will cost $500" some people who really, really have to get moving will pay it. Others will wait. But there are ways around this as you say, like solar and batteries, or contracts that cap the rate, or contracts with other suppliers. In a situation like the Texas shutdown, where people were losing power and freezing, you want to tell drivers to not charge unless it's an emergency. The high price is a good thing. But a high price only works if people are sure to know about it, and shut off everything they can during the high price -- including driving. Fortunately events like the Texas freeze as even rarer than gasoline shortages.

Car chargers will always have a chance to see the price. Your Tesla could honk at you and say, "Caution price is super high now, do you really want to charge?" The people who got burned were people who didn't realize what was going on and blindly used their normal load.

 

[RTPEV]

One comment I've seen repeatedly is that EVSE pay ToU rates plus "burst demand" rates. Supposedly even if commercial electric rates are 2-3c/kWh, when burst demand pricing is applied, the cost per kWH can exceed $1.00

This seems like a somewhat necessary evil, given the unique demands of EVSE.

If the burst demand charges put rates as expensive as $1.00/kWH, it could/should encourage onsite battery storage combined with solar canopies (or even wind). The batteries could be topped off at night with the utility providing more attractive rates, while the solar panels do what they can during the daytime to keep the batteries charged. Then through battery management software, the onsite battery storage could be "trickle charged" throughout the day to reduce these burst demand charges.

Demand charges are not charged by the kWh, but by the kW, and they are usually far higher than $1/kW (in my area, over $10/kW for commercial service).

So what does it mean to charge a per kW demand charge? It basically means that over a given month, the highest peak demand you use from the grid ends up being your demand charge for the month. For example, if you have a Supercharger site with 750kW service, and you have a full site pulling that maximum 750kW all at once, you will have $7500 in demand charges for the month at $10/kW demand charge, in addition to the per kWh electricity charge. Of course you have to spread that demand charge out among all your monthly users (along with equipment charges, real estate charges, insurance, back-end billing and other overhead), so you work out how many kWh you dispense in a typical month and tack on a per kWh surcharge to what you charge customers per kWh to cover the demand charge.

For a busy 8-stall Supercharger site, it's probably not that bad. Maybe you have 3500 sessions per month with an average of 50kWh per session delivered (175,000kWh). The $7500 demand charge "only" adds about $0.043 per kWh. Of course if you were only paying $0.06/kWh, that's a pretty big increase percentage wise. And you've got all that other overhead too.

But if the Supercharger is generally not "busy" and you only have 1500 sessions over the course of the month, except for that one hour of that one day when it's fully loaded, then bam, your demand charge overhead jumps to $0.10 per kWh!

It gets pretty bad for a one- or two-unit site though, as we see with CCS/CHAdeMO sites. Those tend to be lower power of course, but some are 125 kW units. The demand charge for that might be $1500 (assume it pulls 150kW peak from the grid--after all it has its own cooling equipment that takes power as well), but with a single stall you might only have 15 sessions per day (many non-Tesla vehicles charge at 50-80kW and charge sessions are longer on average), or 450 sessions per month, and let's call it an average of 40kWh per session (smaller average battery size) for only 18,000kWh dispensed. Now your demand charge overhead is running $0.083 per kWh!

These are only back-of-the-napkin figures, but it does illustrate how demand charges work and how they need to be accounted for, and why as much as we may not like it as consumers, business model wise, an huge Supercharger site with many empty stalls is generally not a good thing, cost wise, for Tesla.

 

[bradtem]

There is a trick you can do. Simply never ever go over the approved peak. If the station is full, you slow down the cars. You put up a warning on the car screen when I navigate there. You leave buffer so that 1 or 2 can get full speed. You can auction those slots to those who need them. Or FCFS if you prefer. Paired chargers already gave less power to person #2

Or you can even say, if you want to pay the full freight of the highest peak, we'll do it. But I doubt you need that. Most people would accept the lower rate maybe with a discount. ( Indeed those in a hurry can subsidize those not.). So a station should never go above its planned peak.

ToU still applies

 

[e of pi]

Demand charges are not charged by the kWh, but by the kW, and they are usually far higher than $1/kW (in my area, over $10/kW for commercial service).

For a busy 8-stall Supercharger site, it's probably not that bad. Maybe you have 3500 sessions per month with an average of 50kWh per session delivered (175,000kWh). The $7500 demand charge "only" adds about $0.043 per kWh. Of course if you were only paying $0.06/kWh, that's a pretty big increase percentage wise. And you've got all that other overhead too.

But if the Supercharger is generally not "busy" and you only have 1500 sessions over the course of the month, except for that one hour of that one day when it's fully loaded, then bam, your demand charge overhead jumps to $0.10 per kWh!

It gets pretty bad for a one- or two-unit site though, as we see with CCS/CHAdeMO sites. Those tend to be lower power of course, but some are 125 kW units. The demand charge for that might be $1500 (assume it pulls 150kW peak from the grid--after all it has its own cooling equipment that takes power as well), but with a single stall you might only have 15 sessions per day (many non-Tesla vehicles charge at 50-80kW and charge sessions are longer on average), or 450 sessions per month, and let's call it an average of 40kWh per session (smaller average battery size) for only 18,000kWh dispensed. Now your demand charge overhead is running $0.083 per kWh!

These are only back-of-the-napkin figures, but it does illustrate how demand charges work and how they need to be accounted for, and why as much as we may not like it as consumers, business model wise, an huge Supercharger site with many empty stalls is generally not a good thing, cost wise, for Tesla.

It also helps illustrate why Electrify America and others are talking about batteries for stalls and remote/underutilized sites. If you can buy an 80 kWh stationary battery and average the charging for the station in that last example you'd need about 25 kW average, maybe 50 kW peak if you get a couple sessions in close succession? Save $750/month, and the battery setup might pay for itself in 18-24 months.

 

[RTPEV]

It also helps illustrate why Electrify America and others are talking about batteries for stalls and remote/underutilized sites. If you can buy an 80 kWh stationary battery and average the charging for the station in that last example you'd need about 25 kW average, maybe 50 kW peak if you get a couple sessions in close succession? Save $750/month, and the battery setup might pay for itself in 18-24 months.

Both this technique, and @bradtem 's above are examples of peak shaving, and it can be very effective in managing costs. And having on-site battery storage even helps to reduce time-of-use peak charging because you can draw energy stored in the batteries that was charged during off-peak times, even during on-peak hours.

 

[bradtem]

Both this technique, and @bradtem 's above are examples of peak shaving, and it can be very effective in managing costs. And having on-site battery storage even helps to reduce time-of-use peak charging because you can draw energy stored in the batteries that was charged during off-peak times, even during on-peak hours.

Grid batteries are standard for peak shaving on any load. EV s are special in that you can completely control your load

 

[RTPEV]

Grid batteries are standard for peak shaving on any load. EV s are special in that you can completely control your load

I'm not sure I'm following.

Sure, you can throttle back your charging site to shave the peak. I'm not sure what makes EVs unique in that respect, although you do use the word "completely". I suppose this is true in that you can completely throttle it back to zero, although you would then end up with unhappy customers!

 

[bradtem]

Most other loads are not very optional. Factories have to shut down lines to peak shave or cut production.
With EVs, you don't have to go to zero. You just go down to the peak. Yes, giving everybody 150kw is good but giving them all 100kw is really just fine, and giving 80% of them 80kw and giving 20% of them 150kw or whatever you need. EVs are very special. Almost no other load is as flexible, can dial up and dial down use on a moment's notice. It's hard to think of another load that is that flexible.

The reality of it is, customers may not even notice. Most cars at the station will be taking less than full power as you only take that early in the charge. The uber-peak would come if every station has a car that is empty and taking full power. But that's a very rare thing, and all you have to do is not give full power to everybody during that period. It's not like you cut them to zero or even 50% of peak. The moment somebody else slows down or disconnects they go back to getting all the power they can take.

There's no other load like that except charging grid batteries perhaps, or filtering swimming pools. But not many.

 

[RTPEV]

Most other loads are not very optional. Factories have to shut down lines to peak shave or cut production.
With EVs, you don't have to go to zero. You just go down to the peak. Yes, giving everybody 150kw is good but giving them all 100kw is really just fine, and giving 80% of them 80kw and giving 20% of them 150kw or whatever you need. EVs are very special. Almost no other load is as flexible, can dial up and dial down use on a moment's notice. It's hard to think of another load that is that flexible.

I see what you're saying, but I don't necessarily agree that factories as quite as black and white as you say (and not all loads are factories either!) The semiconductor fab I worked at (HUGE consumer of electricity that very much practiced peak shaving) had all sorts of methods they would use to peak shave, including kicking on diesel generators (which is really outside of the scope of what we're talking about), but also managing non-critical loads such as HVAC, or other loads that can be deferred such as wastewater treatment, in the 70% of the site that was not directly related to the manufacturing line. A large manufacturing site will probably have critical loads and non-critical loads that can be shaved. It's accurate to say that both load types can't be throttled as easily as you can a set of 8 EVs at a charging site, but taken as a whole, a large manufacturing site can in fact allow for a pretty fine grained "throttling" of the total load.