Discussion: Powershare [V2X feature currently announced for Cybertruck]

[Olle]

As an advocate of home based microgrids, Tesla's approach with the cybertruck might be quite a breakthrough IF it will seamlessly include solar and the capability to arbitrage energy while on grid. Again, if anyone has more/lasted information, please pass along.

I have the impression that long range and low weight is the priority for the CT pack. At battery day Tesla specifically put the CT and Semi at the far end of high nickel/high energy density.

Since cells are a compromise between cost, cycle life, energy density(ref to mass sensitive in the picture) and power, and looking at the presentation, CT (and Semi) would unfortunately be the last Tesla products I would expect to allow arbitrage while under warranty. CT as back up power makes sense since blackouts usually happen with yearly as opposed to daily frequency and as such won't have a material impact on cycle life.

 

[pdx_m3s]

I have the impression that long range and low weight is the priority for the CT pack. At battery day Tesla specifically put the CT and Semi at the far end of high nickel/high energy density.
View attachment 996924

Since cells are a compromise between cost, cycle life, energy density(ref to mass sensitive in the picture) and power, and looking at the presentation, CT (and Semi) would unfortunately be the last Tesla products I would expect to allow arbitrage while under warranty. CT as back up power makes sense since blackouts usually happen with yearly as opposed to daily frequency and as such won't have a material impact on cycle life.

Agree.

Though I hope that when off-grid I will be able to charge the Cybertruck pack with my solar system (Tesla system; SolarEdge inverter, no PW).

 

[holeydonut]

I have the impression that long range and low weight is the priority for the CT pack. At battery day Tesla specifically put the CT and Semi at the far end of high nickel/high energy density.
View attachment 996924

Since cells are a compromise between cost, cycle life, energy density(ref to mass sensitive in the picture) and power, and looking at the presentation, CT (and Semi) would unfortunately be the last Tesla products I would expect to allow arbitrage while under warranty. CT as back up power makes sense since blackouts usually happen with yearly as opposed to daily frequency and as such won't have a material impact on cycle life.

Unless you’re @jboy210 … where his power goes out any time a fat bird lands on his neighborhood power lines.

 

[Olle]

Agree.

Though I hope that when off-grid I will be able to charge the Cybertruck pack with my solar system (Tesla system; SolarEdge inverter, no PW).

That would be nice. Cybertruck's job in that case would only be to provide frequency. As long as the solar panels are producing so that CT doesn't have to discharge its battery, I see no reason not to. One caveat is when a cloud comes by, your house will shut down if it's drawing more power than shaded PV output.

 

[MP3Mike]

That would be nice. Cybertruck's job in that case would only be to provide frequency.

It would have to do more than that, it would have to absorb any excess Solar power generated, and supplement the solar power if the house was drawing more than the solar was generating. That would be great, but I doubt it will support that, at least at launch.

 

[Olle]

It would have to do more than that, it would have to absorb any excess Solar power generated, and supplement the solar power if the house was drawing more than the solar was generating. That would be great, but I doubt it will support that, at least at launch.

Naturally CT can absorb excess power like any other consumer in the house, if it is intending to charge its battery, but it doesn't have to. Solar inverters dump excess power to the panels if it can't be absorbed.

Supplementing off grid generation on the other hand is probably not in the cards for CT. High energy density cells with a whole truck attached to it seems like a heck of an expensive way to pump kWh in and out.

 

[wwu123]

Naturally CT can absorb excess power like any other consumer in the house, if it is intending to charge its battery, but it doesn't have to. Solar inverters dump excess power to the panels if it can't be absorbed.

Supplementing off grid generation on the other hand is probably not in the cards for CT. High energy density cells with a whole truck attached to it seems like a heck of an expensive way to pump kWh in and out.

I've been curious about that for a portable power station I've pledged on Kickstarter that can be AC coupled to the home. We certainly know batteries can absorb excess power, not sure if the off-grid device generating the sine wave / grid frequency, expecting to export power from the batteries to the loads, are always in a state to both import or export and seamlessly change direction (based on varying home load) while generating the sine wave? In other words, are bi-directional inverters always allowing power to flow from sources to sinks in either direction? I'm not familiar with the design of the inverters and electronics, was curious...

 

[pdx_m3s]

That would be nice. Cybertruck's job in that case would only be to provide frequency. As long as the solar panels are producing so that CT doesn't have to discharge its battery, I see no reason not to. One caveat is when a cloud comes by, your house will shut down if it's drawing more power than shaded PV output.

In your cloud example, I think it would work just like a Powerwall... Cybertruck would fill in the difference by outputting power as needed.

 

[miimura]

How would that work if you were charging from a 120v AC outlet, and trying to use the 240v outlet in the bed?


Correct, and that auto-transformer is in your Powerwall or Powershare Gateway... It is not in the vehicle, as there aren't enough wires to get the neutral out of the vehicle and hooked to your house.

But the inverter, likely completely separate from the bidirectional charger used for V2H, in the vehicle has to support neutral for the 120v outlets, and the 14-50 outlet in the truck.

Clearly, the Neutral issue exists in the truck outlets and in the house and have to be handled separately. People are speculating that the Powershare Gateway must include an auto-transformer and a low voltage dark start power source wired from the Universal Wall Connector. People that already have Powerwalls and Tesla Wall Connector (or even Mobile Connector) don't need the extra wiring or transformer because the Powerwalls can balance the Neutral and remain running off-grid.
I am suggesting that the truck needs its own auto-transformer for its outlets. That would handle the situation of powering the outlets from the bi-directional single voltage charger when fully mobile and also handle the situation where you want to power a load from the outlets when charging from a different voltage. ie. charge on 120V and power a 240V load or vice-versa. Of course, the possibility exists for drawing way more 240V power than the 120V charging is providing, so it would have to be capable of filling in more power from the battery through the OBC in this situation, while in a grid-following mode.

This just gets more and more complicated the more I think about it. I will be really impressed if Tesla pulled this off and it can handle all these situations.

 

[MP3Mike]

People are speculating that the Powershare Gateway must include an auto-transformer and a low voltage dark start power source wired from the Universal Wall Connector.

Not really speculating, have been told specifically by Drew at Tesla:

To provide this current when off grid, you either need a Powerwall, or a new Powershare version of Tesla’s energy Gateway with an auto-transformer in it.

https://twitter.com/x/status/1731184984105558136

Additionally, for homes without a Powerwall, the Universal Wall Connector provides an interface for logic power from the car to the switch in the gateway to power the disconnect open during an outage.

https://twitter.com/x/status/1731186119914754484

 

[miimura]

I've been curious about that for a portable power station I've pledged on Kickstarter that can be AC coupled to the home. We certainly know batteries can absorb excess power, not sure if the off-grid device generating the sine wave / grid frequency, expecting to export power from the batteries to the loads, are always in a state to both import or export and seamlessly change direction (based on varying home load) while generating the sine wave? In other words, are bi-directional inverters always allowing power to flow from sources to sinks in either direction? I'm not familiar with the design of the inverters and electronics, was curious...

When you have an off-grid battery inverter that is capable of AC coupling to grid-tie inverters, it is acting as the micro-grid master and must maintain voltage and frequency. It does that by dynamically charging and discharging the battery to balance the AC micro-grid against generation and loads. When the battery starts to get full and it can't take any more energy, it has to have a way to stop the solar from generating. The only universal way to do this is to move the frequency out of the grid tolerance range. Most grid-tie solar inverters will stop generating at 62.5Hz. Many can be programmed with proportional curtailment as the frequency increases beyond some point like 61.0 Hz to 62.5Hz will curtail from 100% to 0% or have some programmed %/Hz curtailment slope.
When AC coupling, you also have to be careful that you battery inverter has more wattage capacity than the solar. If not, it's possible for the solar to overwhelm the battery inverter and it has no choice but to either curtail the solar or shut it down. This is why most off-grid solar systems used to use solar charge controllers so that the battery could be charged with DC direct from the solar and the inverter was only sized for the loads. The charge controller was programmed with the battery charging parameters and would naturally curtail the solar to match the battery charging parameters.

 

[wwu123]

When you have an off-grid battery inverter that is capable of AC coupling to grid-tie inverters, it is acting as the micro-grid master and must maintain voltage and frequency. It does that by dynamically charging and discharging the battery to balance the AC micro-grid against generation and loads. When the battery starts to get full and it can't take any more energy, it has to have a way to stop the solar from generating. The only universal way to do this is to move the frequency out of the grid tolerance range. Most grid-tie solar inverters will stop generating at 62.5Hz. Many can be programmed with proportional curtailment as the frequency increases beyond some point like 61.0 Hz to 62.5Hz will curtail from 100% to 0% or have some programmed %/Hz curtailment slope.
When AC coupling, you also have to be careful that you battery inverter has more wattage capacity than the solar. If not, it's possible for the solar to overwhelm the battery inverter and it has no choice but to either curtail the solar or shut it down. This is why most off-grid solar systems used to use solar charge controllers so that the battery could be charged with DC direct from the solar and the inverter was only sized for the loads. The charge controller was programmed with the battery charging parameters and would naturally curtail the solar to match the battery charging parameters.

Thanks, appreciate the detailed explanation - I think you're describing the design and behavior of so-called hybrid inverters, I think designed for both on-grid AC coupling and off-grid solar.

The Kickstarter project I have mentioned in another thread is the Anker Solix F3800 - does not describe itself as a hybrid inverter, so it will be curious to see how it actually behaves and what works, vs what they say it officially supports. It might be different than hybrid inverters because of the Home Panel that is the gateway that provides the AC coupling and off-grid backup features. The battery/power station plugs into the Home Panel - but the Home Panel has both a 240V input/output side connected to the main panel, i.e. on-grid use, and a separate 240V output (and maybe input) for the backup load side. The on-grid side is tied to the utility and the on-grid solar via the main panel, really it only distinguishes utility vs-solar power by a CT clamped to the latter, as both are commingled coming into the Home Panel. The Home Panel will cut off the main panel in off-grid situations though, so no need to have curtailment capability for the on-grid side.

The off-grid side of the Home Panel is the question, whether it is bi-directional or not, when running off-grid and powering the backup panel. Officially they don't document a configuration where someone has landed their grid-tie solar breaker into the backup panel, and notably ignored any questions regarding such. Therefore there is expected to be no curtailment or frequency shifting on the backup side, since they didn't design it for off-gird AC solar (it has a separate DC input with MPPT for off-grid solar). The main uncertainty is again whether the 240V inverter is going to naturally be bi-directional or not, when it is facing the backup side of the Home Panel.

My Enphase array is small enough (with only a 30A breaker) that I could manually make sure the solar production is always less than house loads + AC charging limit of the power station, to feed in via the backup panel. But it would only work if the inverter is always acting bi-direcitonally facing the off-grid (backup panel) side. Sorry for taking a tangent - not related to Tesla Powershare thread topic....

 

[brkaus]

This becomes quite the brand lock in, doesn’t it? Significant cost to install something on the home side of things.

 

[MP3Mike]

This becomes quite the brand lock in, doesn’t it? Significant cost to install something on the home side of things.

Unknown. It may be compliant with the CCS V2H standards that are being worked on, but I don't think are finalized yet. (Which I think VW has just announced support of if Europe.)

The current Ford solution is 100% proprietary, and frankly doesn't appear to be very reliable.

 

[pdx_m3s]

Unknown. It may be compliant with the CCS V2H standards that are being worked on, but I don't think are finalized yet. (Which I think VW has just announced support of if Europe.)

The current Ford solution is 100% proprietary, and frankly doesn't appear to be very reliable.

Ford's solution outputs DC from the vehicle, which requires an inverter (and small battery) to be installed on the house-side... quite expensive. It appears VW's solution is like this too. Tesla's solution is unique in that the inverter is onboard the vehicle and it just outputs AC directly to the house.

Ford and VWs solution operates more like a solar PV system, while Tesla's operates like a typical generator.

Ford's systems is about $10k in hardware and labor. Tesla's will likely be ~$5k (wall connector $600, Gateway $1,700-2,500, +labor).

 

[MP3Mike]

It appears VW's solution is like this too.

Does VWs system output DC too? I haven't seen any details, other than it is currently only compatible with one brand/model of storage system installed on the house, but they planned to add compatibility to others. (Sort of like Powershare is compatible with a Powerwall system.) I haven't seen anything about if it outputs AC or DC from the car.

 

[pdx_m3s]

Does VWs system output DC too? I haven't seen any details, other than it is currently only compatible with one brand/model of storage system installed on the house, but they planned to add compatibility to others. (Sort of like Powershare is compatible with a Powerwall system.) I haven't seen anything about if it outputs AC or DC from the car.

I did some research and everything I have read regarding VW/bi-directional charging has presented it as a DC-output system with an inverter. I would be very surprised if it was an AC-coupled system.

 

[sunwarriors]

The current Ford solution is 100% proprietary, and frankly doesn't appear to be very reliable.

Didn't see any issues with the Ford system when watching the State of Charge videos. Are issues due to it being "new" or installers not knowing what to do since it is new?

 

[fhteagle]

Are issues due to it being "new" or installers not knowing what to do since it is new?

I would call many of the issues fundamental design errors, several more come from spreading the engineering, install, etc across three different companies.

Here's an example of one of the many fundamental design errors:

Agreed with others above that the industry really needs to finish writing and publishing workable universal standards for DC and / or AC coupling to the home energy systems. Vendor lock in is not the way.

 

[jjrandorin]

I would call many of the issues fundamental design errors, several more come from spreading the engineering, install, etc across three different companies.

Here's an example of one of the many fundamental design errors:

Agreed with others above that the industry really needs to finish writing and publishing workable universal standards for DC and / or AC coupling to the home energy systems. Vendor lock in is not the way.

This video was interesting, thanks for sharing it.