Discussion: "Powerwall +"

[SilverSp33d3r]

Quick point: with the Green Meter Adapter or Generation Meter Adapter, the cable to the meter adapter is actually carrying the power generated. Whereas the inferred meter adapter that is part of PW+ only needs to have the relay for the Microgrid Interconnect Device; power would flow through the 50A breaker in the main panel installed for connection to the PW+ per the spec sheet.

Cheers, Wayne

Based on Elon’s comments from the most recent call, I believe tesla is trying to avoid installing breakers downstream of the main to avoid 120% rule or limit requiring to de-rate the main breaker.
Until line diagrams for a system are leaked/shared we have no clue.

 

[RKCRLR]

This is the answer I'm looking for: which (Tesla) components would I need to drive my AC, at night and without the grid? Before PW+, the Tesla configurator suggested 3 PW for my fully electric house, mainly to drive the AC units. Is this even possible with the PW+, given the 50A overcurrent protection limit? You mention SureStart as a way to mitigate the current spike when starting the compressor, and that it didn't work in your case. The Powerwall+ brochure says it includes an "integrated soft starter capable of powering motors and air conditioning units (supports devices up to 105 LRA)." Unfortunately, my AC lists 140 LRA (Locked Rotor Amps).

The reason the SureStart didn't work for me is because I have a 2 stage compressor but the low stage of the compressor turns in the opposite direction of the high stage. The SureStart couldn't handle that.
I don't know how an "integrated" soft starter would work. Soft start devices are mounted at the compressor and reduce the current draw during startup so the Powerwall breakers don't trip. If something were built into the Powerwall is seems like it would be something to provide a current surge during high current demand periods.

 

[aesculus]

Tesla is proposing load shedding using a 24V line from the gateway to my AC to stop it from trying to start if the grid is down.

If they decide they cannot drag a 24v line and come up with a wireless solution PM me. I need the same thing but my AC units are "miles" away from my gateway with canyons and dragons between them.

 

[MP3Mike]

If they decide they cannot drag a 24v line and come up with a wireless solution PM me. I need the same thing but my AC units are "miles" away from my gateway with canyons and dragons between them.

I would think that they could install a load shedding circuit breaker. Something like this:

QO240PLILC - Mini circuit breaker, QO, 40A, 2 pole, 120/240 VAC, 10 kA, Powerlink, load shedding, plug in mount - Royal Wholesale Electric Suppliers

www.royalwholesaleelectric.com

Assuming of course the the circuit breaker for the AC is somewhere near the gateway.

 

[RKCRLR]

If they decide they cannot drag a 24v line and come up with a wireless solution PM me. I need the same thing but my AC units are "miles" away from my gateway with canyons and dragons between them.

My AC and breaker are 260' from my Gateway. They plan on digging a trench.

 

[RKCRLR]

I would think that they could install a load shedding circuit breaker. Something like this:

QO240PLILC - Mini circuit breaker, QO, 40A, 2 pole, 120/240 VAC, 10 kA, Powerlink, load shedding, plug in mount - Royal Wholesale Electric Suppliers

www.royalwholesaleelectric.com

Assuming of course the the circuit breaker for the AC is somewhere near the gateway.

My Carrier Infinity system has a computerized communicating thermostat. Just throwing the outside unit breaker will make it have a tizzy fit and throw all sorts of errors. And the interior fan will still run trying to cool unless I manually shut everything down.
Also, my understanding of those breakers is they need to be manually reset to on.
My system has a utility curtailment feature. I'm hoping they'll use that but they seem hesitant.

 

[dhanson865]

This is the answer I'm looking for: which (Tesla) components would I need to drive my AC, at night and without the grid? Before PW+, the Tesla configurator suggested 3 PW for my fully electric house, mainly to drive the AC units. Is this even possible with the PW+, given the 50A overcurrent protection limit? You mention SureStart as a way to mitigate the current spike when starting the compressor, and that it didn't work in your case. The Powerwall+ brochure says it includes an "integrated soft starter capable of powering motors and air conditioning units (supports devices up to 105 LRA)." Unfortunately, my AC lists 140 LRA (Locked Rotor Amps).

You said AC units plural in your 2nd sentence. Is one of them lower LRA than that one that is 140? Could you just put the smaller unit on the powerwall and keep that 140 LRA unit off?

FWIW my only AC unit is 61.5 LRA. That's a 3 ton 20 SEER unit.

 

[aesculus]

My system has a utility curtailment feature. I'm hoping they'll use that but they seem hesitant.

Pretty sure all those do is cycle the compressor. Your fan will still run. But they are only intended to cycle off for 15 minutes or so in an hour, a few times, not keep a unit off for hours.

 

[aesculus]

My AC and breaker are 260' from my Gateway. They plan on digging a trench.

My distance is about the same but there is a lot of concrete between the GW and the panel the loads are on.

 

[Enginerd]

You said AC units plural in your 2nd sentence. Is one of them lower LRA than that one that is 140? Could you just put the smaller unit on the powerwall and keep that 140 LRA unit off?

FWIW my only AC unit is 61.5 LRA. That's a 3 ton 20 SEER unit.

I could... it's the smaller AC unit for the bonus room upstairs. But since I haven't spent any money yet, I'd like to plan for a system that can support a normal-ish life without serious compromises. Imagining July in Georgia, post-hurricane... with the whole family in a tiny room upstairs? Nah. That would be a big step down from a 3xPW system that can run all my stuff.

 

[RKCRLR]

Pretty sure all those do is cycle the compressor. Your fan will still run. But they are only intended to cycle off for 15 minutes or so in an hour, a few times, not keep a unit off for hours.

Perhaps, but my communicating thermostat is pretty smart (too smart for my own good) so it might also know not to run the fan if the compressor isn't running.

Currently, my AC will start if the solar is producing but it takes a lot of coordination. Tesla said that I would not be able to manually override the load shedding so I would no longer be able to run the AC when the grid is down. My system's utility curtailment feature has the option of Disabled, Off, or Low Stage. If they were to tie into that I would still be able to coordinate a start of the AC by changing the setting from Off to Low Stage or Disabled.

Additionally, since my LRA is 130 amps in high stage and my low stage is half the output of the High Stage I figure it takes about 65 amps to start. While that is too much for 2 Powerwalls in the current configuration, 2 of the "upgraded" Powerwalls with the supposed firmware update should be able to start the compressor on low stage even if the Gateway has commanded the solar off.

 

[dhanson865]

I could... it's the smaller AC unit for the bonus room upstairs. But since I haven't spent any money yet, I'd like to plan for a system that can support a normal-ish life without serious compromises. Imagining July in Georgia, post-hurricane... with the whole family in a tiny room upstairs? Nah. That would be a big step down from a 3xPW system that can run all my stuff.

so how many tons is the big unit and how many tons for the small unit (or is it a mini split or window AC?)

 

[slcasner]

The photo appears to show an electric meter adapter, which I assume would be a grid disconnect device (Microgrid Interconnect Device). Note that the meter shows two locking rings, one would be to lock the adapter to the all-in-one-panel, and one would be to lock the meter to the adapter. Plus there is the small flex conduit going from the top component of the Powerwall+ to the meter adapter.

Do you have any pointers to information about the MID implemented as a meter adapter ring? A google search was not very successful.

Displacing the relay out of the Gateway into the adapter ring is key because it avoids the need for large gauge wires to handle the full panel current, especially for homes with an all-in-one main service panel where interrupting the connection between the meter socket and the main breaker is difficult.

 

[wwhitney]

Do you have any pointers to information about the MID implemented as a meter adapter ring? A google search was not very successful.

No, I'm not sure any commercially available products currently exist. But it's certainly possible and Tesla could create and list one.

Cheers, Wayne

 

[miimura]

Quick point: with the Green Meter Adapter or Generation Meter Adapter, the cable to the meter adapter is actually carrying the power generated. Whereas the inferred meter adapter that is part of PW+ only needs to have the relay for the Microgrid Interconnect Device; power would flow through the 50A breaker in the main panel installed for connection to the PW+ per the spec sheet.

Cheers, Wayne

One clever idea would be to design a "Green Meter Adapter" that incorporated the grid disconnect switch. I think that would simplify things a lot. Taking the power directly from the meter and redirecting it completely eliminates dual feed limitations imposed by the main panel.

 

[oholladay]

When I look at the new spec sheets floating around, it is unclear to me which specs relate to the new inverter (and maybe backup gateway 2 replacement) and which relate to the Powerwall. I am curious to know what the "BESS Continuous Power" and "BESS Continuous Current" relate to, because the max here is only 5kW.

 

[wwhitney]

BESS = battery energy storage system. So the continuous battery power on PW+ matches PW2.

Cheers, Wayne

 

[slcasner]

No, I'm not sure any commercially available products currently exist. But it's certainly possible and Tesla could create and list one.

That's my concern -- it might take a long time to get it approved by PG&E and the local AHJ.

One clever idea would be to design a "Green Meter Adapter" that incorporated the grid disconnect switch. I think that would simplify things a lot. Taking the power directly from the meter and redirecting it completely eliminates dual feed limitations imposed by the main panel.

I guess that would require putting the 50A breaker inside the inverter/gateway box?

 

[oholladay]

BESS = battery energy storage system. So the continuous battery power on PW+ matches PW2.

Cheers, Wayne

That was my interpretation as well, but it just didn't seem consistent with Elon's tweet. I was expecting higher peak and continuous for the new PWs

 

[mongo]

@wwhitney would the NEC rules on taps allow a connection between the meter (meter isolation adapter) and main breaker panel if the PW also had a properly rated disconnect?