Featured New DC Fast Discharger for Home

not a bad price compared to the prius inverters that used to be sold.

i would love to see some ppractical data on what a 60kw leaf could run 'for days'.

 

Easy math.

The average US household consumes an average of about 1kW continuously. So, 60kWh could run a house for 2.5 days (60 hours) if you consume the entire battery at 100% efficiency.

 

It is much less than what I've seen for the CHAdeMO systems sold in Japan.

 

I'm not sure I really get this thing.

You get to do your own DC fast charging at home if you happen to have enough AC capacity to feed it?

You get to pull battery power out of the car to supply the home during outages at 2-5x the cost of a standby generator and only works if you happen to have the car at home and charged up during the outage?

 

By the way, the generic name for this approach is "V2G" for "Vehicle To Grid".

Vehicle-to-grid - Wikipedia

 

Let me explain the general concept. I'll use round numbers to illustrate.

The entire US electric grid is capable of 1TW (1,000GW) of peak power. The average power use is around 440GW. The difference is that the grid has to be designed to handle the peak load, which is often the summer afternoon peak cooling load.

The total available power output of all the cars in the US is around 10TW - 10 times as much as the power grid. This is because it takes a lot of power to move a car and we have lots of cars.

This means all the cars put together can easily control the power grid, if there was a way to connect and control them. This "control" has been historically called "ancillary services" and includes many distinct services such as regulation, frequency control, governor, black start and a host of others.

The idea is, if even a small fraction of cars are plugged in and able to do this, they can provide all the normal "ancillary services" the grid needs. As the grid becomes populated with more non-dispatchable sources (such as wind and solar, which are only dispatchable through curtailment or down regulation), then the vehicles could take over as a mass-store of energy for the power grid to meet those differences - the difference between the demand and the currently-available renewable resources.

I worked the math on the power above, and it's obviously plenty. However, energy is another story. You'd need a lot more than a few percent of the vehicles to do daily load following, and way more than all the vehicles to do seasonal storage. Daily load following is on the table as a possibility but seasonal storage is not, using this approach.

This is one reason I like hydrogen fuel cell based PHEVs. You can mass-store hydrogen in similar fashions to the way we mass-store natural gas right now (underground in caverns and aquifers). Most people don't realize how much storage is going on that way, but I'll put it in terms people here can understand - a year's worth of today's storage of just natural gas is about equal to 50 years of today's entire gigafactory battery production. It's a lot of storage.

 

Okay, I get a lot of that. But how useful are electric cars in that puzzle? What happens during a regional evacuation when all the cars get unplugged to be driven to high ground?

What happens when you have lots of commuters driving their cars to large, dense unpowered lots where they can't participate?

I can see the general utility of a DC interface for the home. I just can't see paying thousands of dollars for it unless I'm underappreciating some kind of discount or rebate from the power company.

 

That's what I just explained. They can provide most of the ancillary services and daily load following, but not seasonal storage.

That never happens. Remember, you only need some of the cars plugged in to do these two things. Even in an evacuation, some will remain. Besides, the power grid is interconnected - we only have three in the entire US.

Some will be plugged in. To provide all the grid services, you only need a few percent of all the cars. In an EV world, 95% of cars would be available and perhaps half would be plugged in at any one time.

Ancillary services are something the grid has to pay for, and there is significant revenue involved. It's easy to imagine that people could be receiving micro payments for the services their cars are providing to the grid, and there are lots of way to implement that.

 

This is the point that needed the most reinforcement. Thank you.

I have a better understanding of it now, but I think the gadget is mis-priced by a factor of 10 or more.

 

From the article

This seems to defeat the purpose of having a home DC charger for your EV - IMO. It was revealed not too long ago that when (for example) Tesla charges above 20 kW, an algorithm records the count - so that once the traction pack receives a certain # of charges - & the level is >20kw - (tesla won't say whether that's 100,000 miles, 150,000 miles, or just the number of total >20kw charges) all future Max charge rates drops. So - your max charge rate will no longer be 100KW, or 150KW, or 250KW.
Apparently this is a prophylactic strategy that ensures that traction pack capacity will endure for a long long time, & that's a good motive, but it should be brought forth in the boilerplate, rather than discovering it after the fact... & then, discovering that the manufacturer doesn't even want to acknowledge it - until hard-pressed.
All that to say, why not bump up the product to 20kw. I guess it's because cost would more than likely double.
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Maybe, but not by much.

I just had a quick look, and it looks like it's rated at 7.4kW.

Here's a 7.7kW grid-tie solar inverter for $1,600:

SMA Sunny Boy US-41 SunSpec Inverters | altE

But this device is bi-directional so it's more complicated (it has to have a battery charge control system as well, and bi-directional power flow through the power stage). Perhaps $2-3k in volume but $4k in low-volume seems pretty reasonable to me.

 

Okay, that context helps me see the value a bit better. I appreciate that you're taking the time to make it easier to understand. While I do work in a technical field I'm generally expected to take the power for granted and do things with it.

On the other hand I also maintain the family beach cottage, electrified since 1949 yet never grid-connected. I helped my dad add PV in 1987. I've seen many iterations of home-scale offgrid and directly worked with bits of it for our bespoke electrical system over the years so it's not completely unfamiliar to me, I just don't get to see the same scope or scale you deal with.

 

Similar units have been available in Japan going back to at least the PiP. The converted yen prices were twice as much as this one is suppose to cost, at best. One of those units would have been needed for a Mirai to power a home, which likely why that ability didn't become available here.

It is a Level 1 DC charger. You don't need Level 2 DC charging(formerly Level 3) for charging at home.

 

certainly true - for many. 7kW charge speed is adequate. Even so, there are quite a few folks who purchase quicker on board chargers. The fastest on-board Chargers for tesla, are 80 amps. Our Model X was ordered with a 72 amp on board unit. 7kW's speed on a 100kWh pack could represent as long as 14hrs of charging.
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If you have a 300 mile round-trip commute every day, 7kW might not be enough.

If I had a 300 mile round-trip commute every day, I think I'd use the 240V source to get myself out of that commute.

 

helicopter

 

have a seat . . . . .