Would it be possible for Tesla to make a MS/MX into a intermittent "Powerwall"

[dk10438]

I was wondering if if would be possible for Tesla to create some sort of modified HPWC which would allow for bi directional flow of current with the intent of turning our cars into "mini" power walls without incurring the cost of a power wall since the battery is the most expensive part. I've got solar panels and my electricity is set to TOU and the rates are 42c/KwH between 4-9PM. All other hours are 13 cents so it's a pretty big delta.

I know when my solar panel output exceeds my use, the electricity goes back to the grid and at the end of the year there's a true up. Therefore, It doesn't seem that difficult to create a unit that would be able to supply the house (in part or totally) during high usage hours. Since the battery and Tesla owners already have the battery, it'd be a pretty economical way to have power wall like device. We already know that the HPWC is capable of 19W which isn't insignificant.....

Silly????

 

[Rockster]

Vehicle to grid connectivity has been discussed in a number places and is a very effective way to optimize the grid. It’s been speculated that Tesla doesn’t support it because of extra wear and tear on the batteries and maybe even a concern that people with free Supercharging will cycle between the Supercharger and powering their home.

 

[MP3Mike]

A Powerwall is 14kWh and capable of 5kW continuous, so if you turned your car into a Powerwall it would be anything but "mini".

I think it would require modifications to the car, because there isn't an inverter between the battery and the charge port.

In any case if you use your car for stationary storage you void the battery warranty.

Current Tesla's only come with an 11kW charger. (The HPWC is just a glorified relay box.)

 

[dk10438]

Vehicle to grid connectivity has been discussed in a number places and is a very effective way to optimize the grid. It’s been speculated that Tesla doesn’t support it because of extra wear and tear on the batteries and maybe even a concern that people with free Supercharging will cycle between the Supercharger and powering their home.

too bad this isn't being pursued... supercharging issue could be addressed in a number of ways, ie free supercharged electrons can't go into the house/grid, limit it to the newer cars that are paying for supercharging, only charge that originated from the house can go back into the house, etc. battery wear and tear is another issue

 

[Rockster]

I think vehicle to grid technology will eventually become in integral part of a more modern grid. It only makes sense.

 

[miimura]

There are existing solutions for smart charging that will soak up your surplus solar. See solutions like Zappi. However, as far as I know it's not available in the USA. There are DIY projects that can use your 2nd Gen HPWC as a slave and command the charging current to do the same thing, but it's not at all turn-key.

Exporting power from the car is another thing entirely. The reasons are already listed above.
IMHO, if you need battery storage to go with your solar, it's better that it is working with the house 24/7 and not tied to whether your car is there or not.

 

[dk10438]

im not that interested in doing it myself but would be interested if Tesla had a turnkey option available. I was just thinking "out loud" so to speak.

 

[mblakele]

V2G starts from the idea that batteries are expensive and scarce. Over the long term I see batteries becoming cheap and plentiful. As that happens, V2G won't seem like a very good idea anymore.

Historical comparison: when electric motors were novel for industrial applications, often a factory would only have one motor. They'd run elaborate systems of belts and pulleys all over a factory, so that one motor could power many machines. Nowadays motors are cheap and plentiful, and most people don't even notice how ubiquitous they are. They're designed into machines and household appliances.

Historical comparison: when digital computers were novel, a business might only have one. They'd run multiple terminals to workers' desks as needed. As they became cheaper those terminals became PCs, and some homes even had PCs. Today computers are ubiquitous: most people own several, and carry at least one with them most of the time.

So I think Tesla's R&D efforts are better spent making batteries cheap and plentiful, by improving and scaling up battery manufacturing.

 

[brkaus]

In addition to not having an inverter mentioned above, the v2g could not provide power when the grid is down without extra hardware installed on the house to isolate it from the grid.

 

[RayW]

Powering a house from your Tesla?? That's "crazy talk" -- Tesla doesn't even give us a basic 10A 120V plug in the car to run a laptop or a cooler in the frunk.

 

[Puddles]

I’ve raised this issue and seemingly well-informed people explained that a battery configured for use in an automobile is not a good fit for this application. One does wonder why, though.

I’m sure the utility company would squeal like a stuck pig though. I’d love to pay .13/kWh at night to charge my car, then use that to run the A/C during the day.

 

[Enginerd]

Not quite the same thing, but folks buy (salvaged) Tesla battery modules to basically build their own powerwall. One example is Handeeman on YouTube. I would love to do this if I had a legit source and a decent price.

 

[miimura]

im not that interested in doing it myself but would be interested if Tesla had a turnkey option available. I was just thinking "out loud" so to speak.

I have a Tesla Powerwall system installed at my house. It already measures the solar and grid and knows its own battery SOC. Tesla, if motivated, could implement a solution completely in software to have the car soak up surplus solar. It would use the existing data connections in the Powerwall Gateway and the car. I think Elon has mentioned this in passing, but there is no indication when or if it might be implemented.

 

[mociaf9]

I’ve raised this issue and seemingly well-informed people explained that a battery configured for use in an automobile is not a good fit for this application. One does wonder why, though.

The engineering trades being done to optimize for the vehicular use case vs. the stationary use case means they aren't directly interchangeable without significant performance impacts to each. The expected charge/discharge cycling for stationary power is different from that for EVs. EVs need to optimize for lower weight, so their batteries are optimized for Wh/kg. For stationary, that's almost totally irrelevant. Charging and discharging power requirements are different. Etc. All this means that you'd choose different Li-ion battery chemistries for each, different pack and module architectures, etc.

 

[davewill]

I think vehicle to grid technology will eventually become in integral part of a more modern grid. It only makes sense.

I've always wondered for just WHO it makes sense. If I run my house off the car's battery, then I don't have range available when I want to drive somewhere. Conversely, if I drive somewhere, my car isn't around to soak up power from my solar. The synergy doesn't really seem to be there.

 

[dk10438]

why?? the car is just sitting around inactive most of the time so why not put it to work? the capacity of my car is 100 kW and say I daily charge to 80% and my typical day will consume 10 %. Also say that I don't want to have the discharge go below 30%. That still leaves me with 40 kWh which seems to be more than enough for the 4 hours that I have peak rates. And if I know I'm going to drive the car more that 100 miles that evening, I just turn off the "power wall" feature. Obviously some other issues that I was unaware of, but at least in concept, seems like it would be reasonably practical.

 

[miimura]

I assume that most people work away from home during the day. Different life situations would lead to different conclusions.

The only use case I see for V2H is that when you get home, your car could zero out your grid draw with your car's battery during the evening peak hours and then charge up again in the wee hours of the morning. This is adding additional depth of discharge to your normal driving pattern which would consume some battery life.

Use cases for V2G where you plug in at work during the day are actually more compelling to me.

 

[RecklessFury]

I think it'll work well for extended power outages due to hurricanes or some other issue. Currently grid connected homes are completely without power (unless they have a battery system) in an outage even with panels capable of producing power. Flip a lever to disconnect your solar from the grid, hook up your car and boom, you are in business. The solar will charge the car and your car will provide power with consistent voltage to an inverter to power the home. The down side in this scenario is that if you need to run out for something important, you forfeit the power to your home to do so unless you have another car.

I was recently told this won't be necessary in 2-3 years. Inverter technology will catch up and you'll be able to power your home with just panels and no battery system. This we eliminate most of the benefit I describe in this use case.