Discussion: Powershare [V2X feature currently announced for Cybertruck]

[mongo]

I was hoping Tesla would support this upgrading to a new partial backup topology (in red) with an additional Gateway V3 and home PowerSharing to a non-Powerwall backed wall connector, but alas it seems they won't or can't...

View attachment 1027306

Do you really mean to draw two Gateway in series? That would be troublesome. In line with the non-backed feed to the secondary panel from the original Gateway might work.
Two in parallel has been done with 400A service and Powerwalls. This woukd be similar:
Meter -> 200A main panel ->
-> feed through lugs -> current gateway
And
-> 100 A breaker (or whatever Gateway currently has) -> Powershare GW -> secondary panel

 

[CrazyRabbit]

When will PowerShare be demonstrated?

 

[MP3Mike]

When will PowerShare be demonstrated?

Tesla has shown a promotional video of it working. In the real world? After they finish developing it.

 

[miimura]

Do you really mean to draw two Gateway in series? That would be troublesome. In line with the non-backed feed to the secondary panel from the original Gateway might work.
Two in parallel has been done with 400A service and Powerwalls. This woukd be similar:
Meter -> 200A main panel ->
-> feed through lugs -> current gateway
And
-> 100 A breaker (or whatever Gateway currently has) -> Powershare GW -> secondary panel

My existing main panel houses a CL320 meter. It has one 200A Main Breaker installed feeding the integrated breaker bus. A 125A two pole breaker feeds my Powerwall Gateway. If I wanted to back up some of the other loads in my main panel that are not backed up, I could move those loads to a sub-panel and feed that either from a new main breaker in the empty space, or install another large breaker on the existing main panel bus. The PowerShare Gateway would go between this new breaker and the new sub-panel. There is no good reason this kind of parallel system can't work.

 

[mongo]

My existing main panel houses a CL320 meter. It has one 200A Main Breaker installed feeding the integrated breaker bus. A 125A two pole breaker feeds my Powerwall Gateway. If I wanted to back up some of the other loads in my main panel that are not backed up, I could move those loads to a sub-panel and feed that either from a new main breaker in the empty space, or install another large breaker on the existing main panel bus. The PowerShare Gateway would go between this new breaker and the new sub-panel. There is no good reason this kind of parallel system can't work.

Right, I fully agree with that. Thus my question of whether they meant to draw the Gateways in series such the the PW Gateway would not normally be able to tell if it were being fed by the grid or by Powershare. Versus parallel with each Gateway having its own connection to the meter.

 

[mspohr]

It strikes me as overly complicated to switch all of these AC sources and drains.
I think it would be less complicated and more efficient to just keep everything DC from and to the car battery. Standard Hybrid inverters can do the grid/ load switching when AC is needed.

 

[mongo]

It strikes me as overly complicated to switch all of these AC sources and drains.
I think it would be less complicated and more efficient to just keep everything DC from and to the car battery. Standard Hybrid inverters can do the grid/ load switching when AC is needed.

What is overly complicated?
Grid disconnect switch needs to exist regardless.
An external unit would just be duplicating the Cybertruck's charger.

 

[mspohr]

What is overly complicated?
Grid disconnect switch needs to exist regardless.
An external unit would just be duplicating the Cybertruck's charger.

Three Backup Gateways trying to coordinate.

 

[miimura]

Three Backup Gateways trying to coordinate.

They don't have to switch in unison. The PowerShare Gateway is only going to operate when the vehicle is present anyway. So, the criteria for each one to switch must be independent. That is another reason that they should be parallel and not series.
Ford Backup Power Pro (or whatever they actually call it) also has a limited load capacity, so it should also be independent.

 

[mspohr]

Here's my idea for a simplified universal Powershare system.
This utilizes a commonly available Hybrid Solar Inverter and only requires a Wall Connector with the ability to switch from AC input to DC output.
I realize this is far from what Tesla is offering with their own Power walls and Gateways (and they're not likely to adopt my idea) but it does demonstrate how Powershare could be done more easily.
Love to get feedback.

 

[MP3Mike]

Here's my idea for a simplified universal Powershare system.
This utilizes a commonly available Hybrid Solar Inverter and only requires a Wall Connector with the ability to switch from AC input to DC output.
I realize this is far from what Tesla is offering with their own Power walls and Gateways (and they're not likely to adopt my idea) but it does demonstrate how Powershare could be done more easily.
Love to get feedback.
View attachment 1028356

That is similar to how the Ford system currently works. (Though they use the CCS connector, so you don't have to switch any wires/connections between DC and AC usage.)

It will be interesting to see how Ford does it once they switch to NACS.

 

[mongo]

Here's my idea for a simplified universal Powershare system.
This utilizes a commonly available Hybrid Solar Inverter and only requires a Wall Connector with the ability to switch from AC input to DC output.
I realize this is far from what Tesla is offering with their own Power walls and Gateways (and they're not likely to adopt my idea) but it does demonstrate how Powershare could be done more easily.
Love to get feedback.
View attachment 1028356

Yeah, I've mentioned PW+ or PW3 could direct connect to a battery pack. Add UWC guts and a set of DC contactors and you're good to go. Or two sets of DC contactors and it can switch between solar and Cybertruck. Could even split between MPPTs.
Fancier would be bi-directional charging.

That is similar to how the Ford system currently works. (Though they use the CCS connector, so you don't have to switch any wires/connections between DC and AC usage.)

It will be interesting to see how Ford does it once they switch to NACS.

Good point, especially since the DC portion is just pass-through at the wall connector.

 

[fhteagle]

This utilizes a commonly available Hybrid Solar Inverter and only requires a Wall Connector with the ability to switch from AC input to DC output.

Tesla Wall Connector pulling DC bidirectionally from the car is news to me. Didn't see that in the Gen3 manual. Have a reference for that? I know the EVerest project got a Tesla or two to dispense DC out of the charge port for a few kWh, but that's all I had heard for sure thus far.

I know some other products like the Enteligent TLC, Quasar Wallbox, dcbel DC charger, etc are talking about bidirectional DC, but I haven't heard of any of those headed to customer premises yet.

But this tech is both moving fast and frustratingly slowly. What I knew last week might not be true today.

 

[mongo]

Tesla Wall Connector pulling DC bidirectionally from the car is news to me. Didn't see that in the Gen3 manual. Have a reference for that?

It doesn't, that was their idea for a new system.

 

[fhteagle]

It doesn't, that was their idea for a new system.

Ahh, I was thrown off by the "EVSE" box in the diagram being specifically labeled "Tesla Wall Connector"...

But yes, 100% agreed that DC coupled straight through from solar to the car and back to the inverter is a great idea. Just waiting for standards to fully settle and the prototype products to actually be available instead of the "coming soon" status they've been in for many moons now.......

 

[miimura]

Here's my idea for a simplified universal Powershare system.
This utilizes a commonly available Hybrid Solar Inverter and only requires a Wall Connector with the ability to switch from AC input to DC output.
I realize this is far from what Tesla is offering with their own Power walls and Gateways (and they're not likely to adopt my idea) but it does demonstrate how Powershare could be done more easily.
Love to get feedback.
View attachment 1028356

There are several problems with this diagram.

• The Gateway disconnect is not shown.
• All AC (Wall connector, solar inverter, backup loads) should be shown connected to the Backup Panel.
• The sizing of the solar inverter is limiting the combined output of A) Solar B) Batteries C) Vehicle DC discharge
• The diagram only shows charging direction on AC to the Wall Connector.

The only vehicle that supports PowerShare delivers that power to the home with AC, not DC. I understand that you are proposing a new DC path from the vehicle, and that's in fact, the way that Ford does it. However, Ford is using a dedicated inverter, and a relatively small one at that. Also, in the DC domain, a simple MPPT or PWM "let through" power transistor only works when the DC source voltage is higher than the target (battery) voltage. If you want to go the other way or need the flexibility to charge and discharge regardless or DC voltage differences, you need a DC-DC converter which has higher losses.

As a form of "devil's advocate" let me explain the benefits of Tesla's existing scheme and the benefits of your scheme of adding DC.
Benefits of Tesla'a all AC system where Solar, Battery, and Powershare all have their own inverters and are AC coupled.

• Battery, Solar, and vehicle have dedicated output and each inverter is properly sized for its own purpose and they don't limit each other.
• Safety certification is easier for cables, inverters, EVSE that don't handle HVDC.
• Compatibility is better for incremental additions to a home. Powerwall Batteries can be added to an existing solar system. Powershare can be added to existing solar + Powerwall system.

Benefits of DC connected solar, battery and vehicle:

• Incrementally higher efficiency doing power conversion all in the DC domain. Maybe this is like 98% vs 96% each way, maybe 95% vs 90%, but it depends on relative voltages.
• Possibly tighter integration of each source in the DC domain to control power flows more effectively.

I would argue that AC coupling and having a defined way to communicate command and control signals for things like vehicle discharge rate has more benefits at the expense of slightly lower efficiency.

 

[mspohr]

There are several problems with this diagram.

• The Gateway disconnect is not shown.
• All AC (Wall connector, solar inverter, backup loads) should be shown connected to the Backup Panel.
• The sizing of the solar inverter is limiting the combined output of A) Solar B) Batteries C) Vehicle DC discharge
• The diagram only shows charging direction on AC to the Wall Connector.

The only vehicle that supports PowerShare delivers that power to the home with AC, not DC. I understand that you are proposing a new DC path from the vehicle, and that's in fact, the way that Ford does it. However, Ford is using a dedicated inverter, and a relatively small one at that. Also, in the DC domain, a simple MPPT or PWM "let through" power transistor only works when the DC source voltage is higher than the target (battery) voltage. If you want to go the other way or need the flexibility to charge and discharge regardless or DC voltage differences, you need a DC-DC converter which has higher losses.

As a form of "devil's advocate" let me explain the benefits of Tesla's existing scheme and the benefits of your scheme of adding DC.
Benefits of Tesla'a all AC system where Solar, Battery, and Powershare all have their own inverters and are AC coupled.

• Battery, Solar, and vehicle have dedicated output and each inverter is properly sized for its own purpose and they don't limit each other.
• Safety certification is easier for cables, inverters, EVSE that don't handle HVDC.
• Compatibility is better for incremental additions to a home. Powerwall Batteries can be added to an existing solar system. Powershare can be added to existing solar + Powerwall system.

Benefits of DC connected solar, battery and vehicle:

• Incrementally higher efficiency doing power conversion all in the DC domain. Maybe this is like 98% vs 96% each way, maybe 95% vs 90%, but it depends on relative voltages.
• Possibly tighter integration of each source in the DC domain to control power flows more effectively.

I would argue that AC coupling and having a defined way to communicate command and control signals for things like vehicle discharge rate has more benefits at the expense of slightly lower efficiency.

Thank you very much for this detailed response. You clearly have a better knowledge of the field and have some good comments.
I have just a few clarifications:
Standard home hybrid inverters include an AC disconnect so a gateway is not needed.
I debated whether or not to connect the wall connector to backup or grid. It could be connected to the backup but that would limit the AC power available for grid charging the car.
Yes, the size of the inverter is a limiting factor so that should be taken into account. What is the Tesla Powerwall inverter output power?

A standard hybrid inverter battery is usually 48 volts (sometimes 96 volts) and will take the higher DC voltage from the car and charge the battery and/or invert it to AC for loads.
I didn't plan on DC charging the car. I was thinking this would be primarily a power backup system for a house which could use the car battery as a supplemental battery which is how most people would use it. It would be possible to AC charge the car but the amount of battery power in most home inverter installations would only provide a small boost to the car.

DC Connections:
The system I proposed does pull DC from the car (but does not DC charge the car... does the Tesla system DC charge the car?)

As far as control. The standard hybrid inverter manages the battery, loads, DC solar and car battery input so nothing extra needed there.
The only control part which would be needed is the wall connector which would communicate with the car to tell it when it needed to connect the car battery. (The inverter would take as much power from the car as needed within limits set by the car.)

 

[CrazyRabbit]

I think most people would like ac coupled as it gives more power for off grid. Not everyone has 8 powerwalls like me!

 

[Marcia L]

I'm having Tesla PowerWalls installed next week. Anything the technicians can/should do to make future Cybertruck PowerShare installation easier? And how do I go about asking this question of Tesla? The installer tried contacting them but Tesla didn't respond. I sent a Service Request through the app today, asking this question, even though it's not service and told them I didn't know how else to ask. Still waiting for a response.

 

[mongo]

I'm having Tesla PowerWalls installed next week. Anything the technicians can/should do to make future Cybertruck PowerShare installation easier? And how do I go about asking this question of Tesla? The installer tried contacting them but Tesla didn't respond. I sent a Service Request through the app today, asking this question, even though it's not service and told them I didn't know how else to ask. Still waiting for a response.

Have the Wall Connector installed on the backed-up side of things, ideally on a 60 Amp circuit.