Soft Start/ Sure Start AC Problems

[holeydonut]

Was told by third party installer that whole home back up without soft starts or the Lumin would not meet the design parameters and wouldn't be approved.
My ACs are old (2005) with very high LRA.

Hmmm, have you tested whether your Powerwalls can start your ACs (with the utility turned off)? I can see why Lumin would solve a pragmatic problem of your ACs being more carefully managed so they only turn on when you're ready for it with smart load center management. But I don't see how Lumin solved a code compliance problem.

 

[holeydonut]

My 2 Powerwalls will start my compressor in low stage if nothing else is running and it is a "cold" start (not a restart after a recent shutdown); or if the solar is producing. However, if the grid goes down the first thing the Gateway does is shut off the solar. The switchover isn't quick enough to keep the AC going if it is running when the grid goes down.

Huh... so you're saying that once the Gateway has isolated your home to its little microgrid... that you can start the AC on the low/first phase as long as the sun is up? This sounds like the whole home backup is kind of working for you? The Gateway isn't a UPS... I think some form of interruption is to be expected with the loads coming back online later even in the best case scenario with Powerwalls.

I have a whole home backup. Earlier this year I was running my house 100% off of the Powerwalls and solar (the excess solar was going into the Powerwalls). When PG&E went dark for a few minutes, the Gateway still gave me a 2 second power dip and most of my electronics shut down and had to re-start. So even though I wasn't actively relying on PG&E at all during the time the PG&E outage occurred, I still saw an interruption when the Gateway did it's thing to isolate the local home microgrid.

 

[RKCRLR]

Huh... so you're saying that once the Gateway has isolated your home to its little microgrid... that you can start the AC on the low/first phase as long as the sun is up? This sounds like the whole home backup is kind of working for you? The Gateway isn't a UPS... I think some form of interruption is to be expected with the loads coming back online later even in the best case scenario with Powerwalls.

I have a whole home backup. Earlier this year I was running my house 100% off of the Powerwalls and solar (the excess solar was going into the Powerwalls). When PG&E went dark for a few minutes, the Gateway still gave me a 2 second power dip and most of my electronics shut down and had to re-start. So even though I wasn't actively relying on PG&E at all during the time the PG&E outage occurred, I still saw an interruption when the Gateway did it's thing to isolate the local home microgrid.

Yes, but there are nuances. As I said, the switchover causes problems. And once the power is interrupted, even briefly, my spa starts up at full blast 5 minutes later. If I'm not home, there can be an endless series of AC start attempts and Powerwall recycles until the house cools off at night. I can turn off my AC remotely using an app but I have to know a power outage occurred and my AC can't be in a reset cycle which takes about 15 minutes to complete. Once the reset cycle is done it attempts to restart if the temperature demands.

If I'm home I can do load management but it isn't easy. If the Powerwalls reset the solar is commanded off for 5 minutes mimum. My solar isn't commanded on until my Powerwalls reach about 92% SoC. If my house isn't using much energy (which it isn't if the AC isn't running) the Powerwalls recharge really fast and command the solar back off. As I mentioned, my HVAC is a computerized system. I can tell it that I want to cool but it does a system checkout and commands the compressor on when it is damn well ready. This in itself can take 15 minutes depending on the last reset. If I can get it going it will continue to operate unless it reaches its set point or tries to change to high stage, but I can manage those. But it is a PITA.

Since Tesla was proposing removing the system completely I asked what would happen if I did nothing. At least I had some AC during an outage. They told me they weren't happy with the Powerwall reset cycles and may not warranty my system.

 

[holeydonut]

Yes, but there are nuances. As I said, the switchover causes problems. And once the power is interrupted, even briefly, my spa starts up at full blast 5 minutes later. If I'm not home, there can be an endless series of AC start attempts and Powerwall recycles until the house cools off at night. I can turn off my AC remotely using an app but I have to know a power outage occurred and my AC can't be in a reset cycle which takes about 15 minutes to complete. Once the reset cycle is done it attempts to restart if the temperature demands.

If I'm home I can do load management but it isn't easy. If the Powerwalls reset the solar is commanded off for 5 minutes mimum. My solar isn't commanded on until my Powerwalls reach about 92% SoC. If my house isn't using much energy (which it isn't if the AC isn't running) the Powerwalls recharge really fast and command the solar back off. As I mentioned, my HVAC is a computerized system. I can tell it that I want to cool but it does a system checkout and commands the compressor on when it is damn well ready. This in itself can take 15 minutes depending on the last reset. If I can get it going it will continue to operate unless it reaches its set point or tries to change to high stage, but I can manage those. But it is a PITA.

Since Tesla was proposing removing the system completely I asked what would happen if I did nothing. At least I had some AC during an outage. They told me they weren't happy with the Powerwall reset cycles and may not warranty my system.

Thanks for the additional info. I think MJ_CA_2019's idea of adding a smart load center may be cheaper than overhauling your HVAC. The Lumin panel he describes can be set up to manually shed loads in the event of a grid outage. So your ACs, Spa, and other heavy draw items could be shed with the breaker deactivated. Later, when you feel the time is right, yon override the setting and re-activate the breaker. Presumably this gives you enough control to figure things out.

The catch-22 would be that having a Lumin installed is almost the same cost as just adding another battery. And both approaches requires some work and re-permitting. Tesla probably won't pay for the Lumin or another battery out of their pocket.

 

[livingxl]

I am having a similar issue. Tesla installed solar panel and 2 Powerwalls last December (with whole house backup and I will leave 2 out 3 ACs off if there is outage). As part of the install, they put Surestart on all 3 AC units. This summer, 2 out of 3 ACs are having hard time starting (I could hear the compressor struggle to start) and causing flickering of lights in rooms that share the same subpanel. In the past few days, it even caused power failures in these rooms. The flickering and power failures happened when the house was powered by the grid; and the circuit breakers remain in the “On” position after the power failed. When I switched the breakers to off and then on, the power would not come back.

The rest of the house is not impacted, and power remains on. Also, the 3rd AC in the main panel does not have any issue. All 3 ACs are same brand and installed at the same time (7 years old).

Any thoughts on what caused the flickering; and what caused the power failure in the rooms?

I have reached out to Tesla Support and they have yet to schedule a service visit.

 

[RKCRLR]

Thanks for the additional info. I think MJ_CA_2019's idea of adding a smart load center may be cheaper than overhauling your HVAC. The Lumin panel he describes can be set up to manually shed loads in the event of a grid outage. So your ACs, Spa, and other heavy draw items could be shed with the breaker deactivated. Later, when you feel the time is right, yon override the setting and re-activate the breaker. Presumably this gives you enough control to figure things out.

The catch-22 would be that having a Lumin installed is almost the same cost as just adding another battery. And both approaches requires some work and re-permitting. Tesla probably won't pay for the Lumin or another battery out of their pocket.

Tesla won't do anything that is "out of the box". If they would, they could just connect the Gateway load shedding terminals to my utility saver terminals on my HVAC outside unit instead of trying to splice into my thermostat wires. It's pretty simple. The Gateway load shedding terminals go open when the grid goes down. When enabled, the utility saver on my HVAC system turns off the compressor when the circuit goes open. I can then switch the utility saver setting from off to low stage only to manually turn on the AC from the wall thermostat. The main problem is the utility saver doesn't react fast so if the AC is running when the grid goes down it will trip the Powerwalls. But after that it won't try to restart automatically.

A 3rd battery wouldn't need to be added to make the system work as it is supposed to. Tesla could just replace the existing Powerwall 2s with the updated Powerwall 2s. As I said, I'm so frustrated with trying to work with them at this point that is what I'm pushing for (or a possibly a firmware update but that would take internal communication within Tesla).

 

[h2ofun]

Tesla won't do anything that is "out of the box". If they would, they could just connect the Gateway load shedding terminals to my utility saver terminals on my HVAC outside unit instead of trying to splice into my thermostat wires. It's pretty simple. The Gateway load shedding terminals go open when the grid goes down. When enabled, the utility saver on my HVAC system turns off the compressor when the circuit goes open. I can then switch the utility saver setting from off to low stage only to manually turn on the AC from the wall thermostat. The main problem is the utility saver doesn't react fast so if the AC is running when the grid goes down it will trip the Powerwalls. But after that it won't try to restart automatically.

A 3rd battery wouldn't need to be added to make the system work as it is supposed to. Tesla could just replace the existing Powerwall 2s with the updated Powerwall 2s. As I said, I'm so frustrated with trying to work with them at this point that is what I'm pushing for (or a possibly a firmware update but that would take internal communication within Tesla).

There is no data yet that says anything about which powerwall 2's can be upgraded, officially that i have heard.

 

[RKCRLR]

There is no data yet that says anything about which powerwall 2's can be upgraded, officially that i have heard.

Yes, but I bet someone within Tesla knows. But, again, that would require communication within Tesla. And communication doesn't seem to be in Tesla's wheelhouse.

 

[h2ofun]

Yes, but I bet someone within Tesla knows. But, again, that would require communication within Tesla. And communication doesn't seem to be in Tesla's wheelhouse.

So far everytime I talk to powerwall support, I get the feeling they know, but cannot say anything yet. If I were you, I would call once a week and see if they can answer the question yet

 

[RKCRLR]

So far everytime I talk to powerwall support, I get the feeling they know, but cannot say anything yet. If I were you, I would call once a week and see if they can answer the question yet

That's another freekin problem. My Executive Resolutions specialist doesn't answer the phone nor return phone calls or emails. And when I call the normal phone number they see I have a case in Executive Resolutions and tell me they can't talk to me, they can just leave a message for my Executive Resolutions specialist. When I say she doesn't return phone calls and ask to escalate the case they say I've already escalated it as high as I can. My Executive Resolutions specialist says they can talk to me about other items outside of the case but they think they can't.

 

[MJ_CA_2019]

But I don't see how Lumin solved a code compliance problem.

It wasn't a code compliance or inspection issue. Tesla (or the third-party installers interpretation) wouldn't warranty the whole home backup if my main AC was on the backup panel (whole home) unless load shedding was installed. 3 PW is enough for my home. To consider 4 I would have had to increase my PV sizing.

 

[holeydonut]

It wasn't a code compliance or inspection issue. Tesla (or the third-party installers interpretation) wouldn't warranty the whole home backup if my main AC was on the backup panel (whole home) unless load shedding was installed. 3 PW is enough for my home. To consider 4 I would have had to increase my PV sizing.

Oh ok so they thought you'd basically create a "short cycle" issue. But instead of a normal HVAC short cycle, you'd have a constant feedback loop where your AC would attempt to start and trip the 3x Powerwalls if they weren't able to support the LRA.

I'm really surprised Tesla Energy hasn't gone into the business of making their own smart load centers. I mean, inverters and batteries may be their obvious wheelhouse; but the thing that impresses me about Tesla the most is how they take over parts of their supply chain and just make what wasn't available to solve real problems. Their automobiles do not exist because Denso, JCI, Getrag, ZF, and Harman were already making cool parts, and Tesla just paired them with an EV drivetrain. To get their vehicles at this type of volume and scale, Tesla basically took over the supply chain and made the parts that did the things they needed to make this ecosystem work.

I wonder why Tesla hasn't taken a shot into the business of load centers since ultimately the smart tech is really just a way to put power through these load centers in an intelligent (and hopefully green) way.

 

[h2ofun]

It wasn't a code compliance or inspection issue. Tesla (or the third-party installers interpretation) wouldn't warranty the whole home backup if my main AC was on the backup panel (whole home) unless load shedding was installed. 3 PW is enough for my home. To consider 4 I would have had to increase my PV sizing.

why would you have to increase your PV for 4? I have 5 PWs with 15K

 

[Tim-in-CA]

I'm also a little confused on this issue. I have 8.16PV + 2PW and 2 AC units (one for each level). They moved one AC unit breaker to the new load center that is backed up and added a soft start. The other AC unit was left on the main breaker box. When my grid is down, for sure only the backed up unit functions and pulls power from PV and batteries. However, with grid up, the 2nd non-backed up unit will also pull power from the grid/batteries. I thought that the 2nd AC unit would only pull power from the grid. I'm OK not having it backed up during an outage, but am OK it pulling from batteries (if available) when grid is up.

 

[MJ_CA_2019]

why would you have to increase your PV for 4? I have 5 PWs with 15K

It wouldn't have been a requirement of Tesla, just my opinion that the priority would have been PV size increase over adding a 4th PW.