Discussion: "Powerwall +"

[wwhitney]

What is the wiring and fuses for the powerwall +?

Why the 80%?

A) 50A

B) A negative attribute of all panels that holds multiple breakers is that for continuous loads (constant maximum current for > 3 hours), a breaker may trip at below its nameplate rating. As a result, breakers for continuous loads get upsized by a 125% factor; i.e. the maximum continuous load a breaker supports is 80% of nameplate rating. A side effect is that the wiring needs to get upsized accordingly, so that it is properly protected by the upsized breaker, even though wiring can handle 100% of ampacity on a continuous basis.

Cheers, Wayne

 

[h2ofun]

PW+ on grid power is throttled at 7.6 kW export to allow compliance with the 120% rule when interconnecting with a main panel with 200A busbar and 200A main breaker. When off grid, it's not necessary to throttle the power export, and the 50A breaker used for the power connection is sufficient for 9.6 kW continuous (with active PV)


A) Yes. Note that the original PW2 spec was 5 kW continuous but 5.8 kVA continuous--the latter allows for power factors other than unity. So PW2 has always been able to handle 24A continuous current, but the real power has been limited to 5 kW.

B) Probably

C) Maybe, but as you noted there are multiple part numbers for Powerwall 2, so it may be that only the newer model support this. Probably moot anyway as I doubt Tesla will want to deal with going back and reconfiguring those 30A breakers, along with reconsidering whether the existing upstream equipment and wiring complies with the NEC 705.12 requirements for the increased export.

Cheers, Wayne

Wayne, I thought the big positive would be an increase in the surge current, which would help start things like AC. Never heard an issue with continuous power need. So as you have posted before, a 30 amp breaker could handle a 7.5Kw surge would it not? This is all I am expecting with new fw, not an increase in continuous, which who needs?

 

[wwhitney]

So as you have posted before, a 30 amp breaker could handle a 7.5Kw surge would it not?

Sure, no problem. Note the PW+ spec sheets lists the "Peak Off-Grid Power" as what it can deliver for a 10 second period. [And presumably doesn't list Peak On-Grid Power because it doesn't matter, the grid can provide any peak current required by loads.] Note that with sufficient PV to power the PV inverter in the upper box, the PW+ says it can do 22 kW peak for 10s.

That's 92A, which for 10s is OK for a 50A breaker, it should hold. Very high currents (hundreds of A) will trigger a breaker's instantaneous (magnetic) trip functionality, which takes some small number of AC cycles (each cycle being 1/60 s). But on overload a breaker will only trip via its thermal element, once that element heats up enough. That gives an "inverse time" relationship, where the higher the current, the quicker the breaker will trip. I believe that for current of 2x nameplate rating, a breaker per the UL spec is to take longer than 10s to trip.

Cheers, Wayne

 

[slcasner]

The PW+ spec for load start capability is 118 A LRA. My A/C unit is 129A LRA. I could live without backing up the A/C, but the only practical installation with my combo meter + main panel is the meter adapter Backup Switch which means whole-house backup. Earlier there was some discussion of internal soft-start capability with the PW+, but I guess the 118A LRA rating already accounts for that. Could an external device do more? Or could the A/C just be prevented from running if the grid is down? Other options?

 

[h2ofun]

The PW+ spec for load start capability is 118 A LRA. My A/C unit is 129A LRA. I could live without backing up the A/C, but the only practical installation with my combo meter + main panel is the meter adapter Backup Switch which means whole-house backup. Earlier there was some discussion of internal soft-start capability with the PW+, but I guess the 118A LRA rating already accounts for that. Could an external device do more? Or could the A/C just be prevented from running if the grid is down? Other options?

Just do not turn it on if the power it out. That is how I wired my house with batteries and generator. I own deciding what things I run. If I run too many things, or the wrong things, I pay the price.

 

[arnolddeleon]

The PW+ spec for load start capability is 118 A LRA. My A/C unit is 129A LRA. I could live without backing up the A/C, but the only practical installation with my combo meter + main panel is the meter adapter Backup Switch which means whole-house backup. Earlier there was some discussion of internal soft-start capability with the PW+, but I guess the 118A LRA rating already accounts for that. Could an external device do more? Or could the A/C just be prevented from running if the grid is down? Other options?

How old is the unit? Have you considered replacing the A/C? New inverter based units would solve the problem and are significantly more efficient. You could even upgrade to a heat pump.

Are you doing only one Powerwall?

 

[slcasner]

Just do not turn it on if the power it out.

I would consider that an acceptable solution so long as nothing would be damaged if I didn't notice that the grid had dropped while the A/C was on. I was assuming Tesla might not be wiling to accept such a plan.

How old is the unit? Have you considered replacing the A/C? New inverter based units would solve the problem and are significantly more efficient. You could even upgrade to a heat pump.

Are you doing only one Powerwall?

The unit is 20 years old, but we use it max 15 days a year, so I'd rather not buy a new one. But given that we are supposed to be moving away from gas, I suppose I should be thinking about a heat pump.

The order as it currently stands is 6kW Solar Roof and two Powerwalls.

 

[arnolddeleon]

I would consider that an acceptable solution so long as nothing would be damaged if I didn't notice that the grid had dropped while the A/C was on. I was assuming Tesla might not be wiling to accept such a plan.

The unit is 20 years old, but we use it max 15 days a year, so I'd rather not buy a new one. But given that we are supposed to be moving away from gas, I suppose I should be thinking about a heat pump.

The order as it currently stands is 6kW Solar Roof and two Powerwalls.

I would expect the second Powerwall assuming will give you more surge capacity so the pair should handle you existing AC (speculation on my part).

I get you on the A/C usage. I installed my first heat pump about 16 years ago. For the first 15 years we probably used the AC side about 10-15 days a year but it a got work out during the winter heating (my gas furnace was just for backup). For cooling I would have to actively have to remember to turn it on if the forecast was for one of the heat waves. When the compressor died last year I upgraded to an inverter based unit. So much more efficient! Since I've been working at home I just keep the HVAC system in Auto.

 

[Notadog]

Does anyone have any more information on the rollout schedule for the Powerwall+?

I have an install in the SF Bay Area scheduled for next week, so I'm wondering 1) how I can find out if they are going to install a Powerwall+ or not and 2) if it's worth it to ask if my install can be delayed in order for me to get the new Powerwall+.

 

[slcasner]

Does anyone have any more information on the rollout schedule for the Powerwall+?

I have an install in the SF Bay Area scheduled for next week, so I'm wondering 1) how I can find out if they are going to install a Powerwall+ or not and 2) if it's worth it to ask if my install can be delayed in order for me to get the new Powerwall+.

I'd really like to know the answer to that question, too. It depends not only on Tesla's production schedule but also approval by PG&E and the local AHJs.

 

[bayareaever]

My pending install is not going to include the +. I was told that vertical clearance in my basement is not sufficient for the increased height and I have no where else to put the PWs.

For me it’s not a deal breaker, because the increased output probably won’t be needed during outages. I’m getting 3 PWs, so even with the old model that’s still almost 18kw continuous. For 1 or 2 PW installs, I can see it being more of an issue.

 

[h2ofun]

My pending install is not going to include the +. I was told that vertical clearance in my basement is not sufficient for the increased height and I have no where else to put the PWs.

For me it’s not a deal breaker, because the increased output probably won’t be needed during outages. I’m getting 3 PWs, so even with the old model that’s still almost 18kw continuous. For 1 or 2 PW installs, I can see it being more of an issue.

No conclusion on whether "old" pws with a fw update will get increase output SURGE

 

[bayareaever]

No conclusion on whether "old" pws with a fw update will get increase output SURGE

Depends how you define ‘old’. Old model or old manufacture date? Elon said ~11/20 was manufactured cutoff date but who knows.

Current language on website says 5.8/10 kw continuous/surge for standard PW. That’s a big jump from previous 5/7kw rating and will obviously depend on ambient temperature, SOC, etc. just like PW+ presumably.

 

[h2ofun]

Depends how you define ‘old’. Old model or old manufacture date? Elon said ~11/20 was manufactured cutoff date but who knows.

Current language on website says 5.8/10 kw continuous/surge for standard PW. That’s a big jump from previous 5/7kw rating and will obviously depend on ambient temperature, SOC, etc. just like PW+ presumably.

Talking to support a few times, they know stuff but cannot say. They are NOT happy Elon made a comment, since it is not clear if that is "real" Time will tell. Luckily it does not matter to me.

 

[Yubakram]

Hello all. New member and been looking through these forums which have been very useful. We have a 16.32 PV and 3 PW being installed next week. I reached out to make sure they have a “soft start” for our AC unit. I was told that they are installing Series 3 PW’s and the soft start will not be necessary. Is the PW 3 the same as the PW+? I’ve requested a spec sheet.

 

[willow_hiller]

Hello all. New member and been looking through these forums which have been very useful. We have a 16.32 PV and 3 PW being installed next week. I reached out to make sure they have a “soft start” for our AC unit. I was told that they are installing Series 3 PW’s and the soft start will not be necessary. Is the PW 3 the same as the PW+? I’ve requested a spec sheet.

They might be referring to the Powerwall 2s made since late 2020. The serial numbers on those start with 301, which could explain the "Series 3."

You can read what 3 Powerwalls can backup here: What Does Powerwall Back Up | Tesla Support Depending on your AC unit, it might not need a soft starter.

 

[Yubakram]

Thanks for the insight. Just received the Plan-Set and you are correct, 3- PW 2.1 #3012170-05-B.

 

[bayareaever]

Thanks for the insight. Just received the Plan-Set and you are correct, 3- PW 2.1 #3012170-05-B.

My plan set (probably written in January but not installed yet) looks like this. I wonder if I need to insure I’m getting the latest ‘non +’ models.

 

[willow_hiller]

I'm also curious what this internal naming reveals about what Tesla has in the works.

Would they call it Powerwall 2.1 if they didn't already have a Powerwall 3 in the pipeline?

 

[Notadog]

Are project advisors able to tell you the serial number of the Powerwall before an install so that you know which version you are getting?