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Powerwall 2 - New install, but keeps cutting my home power while charging

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Hi all,

Very happy to have found this forum. I'm struggling a bit and am hoping someone is familiar with my issue.

I had a new Powerwall 2 installed on 25th Nov (2 weeks ago).

It is installed as a Backup only (i.e. large UPS essentially). I live in South Africa, so this is to combat the rolling blackouts each day. I may look at solar as well in future, but for now, financially, I have opted for battery alone as a sanity protector :).

Following installation, and following the very first black out (26th), when grid was once again available, the unit began charging, but a few minutes later cut the power to the home (and in this first instance the earth leakage switch also tripped).

I reported this to the installer, who told me they would log a support ticket with Tesla, which they apparently did.

Fast forward two weeks, there has been no word from Tesla, and installers just note that they are unable to troubleshoot this from their side, and "only Tesla" can.

Whether or not this is true, I have been looking into the issue myself and have found the following:

  • The unit seamlessly switches to battery when grid becomes unavailable
  • The unit seamlessly switches to grid when it becomes available, and begins charging
  • The unit charges at 5 Kwh mostly
  • After a minute, or few minutes, and while charging (and if I watch the App), the unit goes through a series of "grid outage detected", switching back and forth between charging and discharging
    • The grid is on and available during this time (as my neighbours all have power and are not experiencing dips or outages)
  • Now the real issue:
    • Periodically, when encountering one of these, the unit will just cut the power to my home
    • And in one out of 4 times the earth leakage will also trip

Below is what these "micro stutters" look like:

Screenshot_20221209_123837_com.teslamotors.tesla.jpg



There were 6 of these following the 4-hour outage yesterday, two of which were accompanied with cutting power to the home.

The installer, while being "Tesla certified", say they've never seen this before, and also noted that the Powerwall should not be charging at 5Kw.

They also did not know how to setup the App, nor did they know what the Operating modes are, or how these are to be setup. (I suspect that someone gave them guidance re the gateway, as they seemed to be on the phone with someone while they worked on that.)

When "assisting" me setup the App, they basically "button bashed" their way through until it accepted their input. My fear is that they did this same thing while setting up the gateway and while using whatever installer configuration settings they have access to. (Welcome to South Africa I suppose. )

Anyway, I have read on this forum that the PW's are able to charge at 5KW (and is not necessarily a problem), and the fact mine is, could be tied to the Time-based operation mode, which is the only operation mode available to me through the App currently. This is set to Backup 100%. And then blank entries or junk data for the periods.

I have a lot of theories, sans any assistance from Tesla or installer:

  1. There is not enough grid available post outage to allow the PW to charge at 5kw + home to pull, thus PW thinks there is a "grid outage"
    1. And is perhaps not fast enough in adapting /balancing its charge rate/pull in the event that the incoming grid availability is variable as the community comes back online.
  2. Frequency-Watt mode (ramp up and ramp down) is not correctly tweaked to allow for local grid variation
    1. I believe this is one of those settings which only Tesla can tweak?
  3. The unit was just plain installed and setup incorrectly
  4. The unit is faulty

Currently my hope is that if I am able to set the Time-base settings in some way, in order to limit the charging to 3.3KW, that this may help to alleviate the issue, or at least cancel potential cause #1 above. (If anyone knows of a setup re Time-based custom settings which could cause the PW to limit down to 3.3, please let me know?)

One last theory I have is that the PW mistakenly registers a "grid outage" when there is not one, and while it is still connected to grid. The combined pull for it charging (5kw) + the homes pull exceeds what it is able to use. We cannot push power back into the grid in SA, so it may be behaving like an off-grid unit when it receives more power from a solar installation than what it can use to charge/discharge with + what the home is pulling. It just shuts down and the home loses power as there is more power than it can deal with. So, it almost thinks the grid is alternative incoming (solar).

Me spit-balling, but long story short is that I could use any expertise and help available, as I am definitely not going to get it from installer, and Tesla seems to take weeks.

I have no way of bypassing the Tesla unit, so I need to find a way to stop these power cuts.

Many thanks for any help,
Jason
 
It is very likely that the operation of Powerwalls is different in different countries. It may also vary depending on whether you have solar or not. I'm in the US and have solar, and my Powerwalls will not charge at more than 1.6 kW each unless they are above the backup reserve in TBC. The behavior you're describing is different than this. I think Tesla will have to answer your question. Your guesses seem plausible to me, but I don't think there's a way to confirm anything without more data, which Tesla will have.
 
@exsar First, sorry to hear of your difficulties. Second, have you put a voltage monitor on your power as power is restored?

Have lived places with rolling power outages and brownouts, I know first hand the hassle, and how "non-standard" the actual power can be.

My suspicion is that sometimes when the power is "restored", there are still remain substantial (from the Powerwall's perspective) variations in the grid voltage.

I am not familiar with the "earth leakage". If it is similar to a ground fault interrupter device, then the grid voltage variations can cause devices in your home to appear to be leaking current, when it is actually the grid that is varying. Things like laptop chargers, and other digital electronics are most likely to cause these sorts of issues. While you could test it by disconnecting your electronics and waiting for the grid to be restored, short of an autotransformer, I don't know how you would solve it. I would double check that all of the earth connections are present, and tightened to the appropriate torque.

While Powerwalls can charge and discharge at 5kW, they are often programmed to charge at lower levels, such as 3kW. Again, in the face of an unstable grid, charging at a high level (5kW) is likely to make your local grid voltage worse, i.e. less stable, compared to a lower charging level. I would hope that your installer would be able to log in to your Gateway and change that parameter.

All the best,

BG
 
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@exsar First, sorry to hear of your difficulties. Second, have you put a voltage monitor on your power as power is restored?

Have lived places with rolling power outages and brownouts, I know first hand the hassle, and how "non-standard" the actual power can be.

My suspicion is that sometimes when the power is "restored", there are still remain substantial (from the Powerwall's perspective) variations in the grid voltage.

I am not familiar with the "earth leakage". If it is similar to a ground fault interrupter device, then the grid voltage variations can cause devices in your home to appear to be leaking current, when it is actually the grid that is varying. Things like laptop chargers, and other digital electronics are most likely to cause these sorts of issues. While you could test it by disconnecting your electronics and waiting for the grid to be restored, short of an autotransformer, I don't know how you would solve it. I would double check that all of the earth connections are present, and tightened to the appropriate torque.

While Powerwalls can charge and discharge at 5kW, they are often programmed to charge at lower levels, such as 3kW. Again, in the face of an unstable grid, charging at a high level (5kW) is likely to make your local grid voltage worse, i.e. less stable, compared to a lower charging level. I would hope that your installer would be able to log in to your Gateway and change that parameter.

All the best,

BG
Site import limit could be set in the Tesla commissioning wizard in these cases to prevent the total home draw from exceeding some number. If your installer would set this number at 3000w then the powerwall would charge at about half rate and this would reduce the demand spike on the grid. I do not know that will fix your issue, but would lower the demand on the grid. The Powerwalls do stop charging when they detect a significant voltage drop.

However being that I know so little about the equipment in another country I know that I really do not know what is going on here. Everything I am saying is speculation based on my experience in the US.

I would get a "kill-a-watt" or similar meter and just leave it in your wall socket in an obvious location. Likely the grid voltage is still available, but it is so low that the powerwalls think there is a brownout. When the rolling blackout happens, watch the voltage in the kill-a-watt, when you see this objectionable behavior.

I do not know why the Powerwall drop your loads entirely though, except that other people in your country have reported long waits for the Powerwall to isolate and start to serve loads. However this could also be a failure of hardware or software in the Tesla gateway as well. Also your installer should check the torque of the terminations.

In the commissioning app, I wonder what the grid code is set to? It may be that there are specific characteristics of your local power grid that are confusing the Tesla powerwall. It also might be true that your grid code is set incorrectly, or that there is no grid code in the Powerwall firmware that really captures the specific grid in SA.

I assume your service is single phase, 230V 50 hz?
 
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Many thanks for the replies! It gives me a lot of detail to work with.

I spoke to the installer yesterday and arranged that they send their senior Tesla technician out to my home to troubleshoot mid next week.

I will ask him to set the charge rate lower (they seemed unsure re this when I initially requested it last week, and deferred to Tesla), and I will mention the commissioning wizard and setting parameters here to lower it. They likely do not know this. (But perhaps it is also not available here, but I couldn't imagine why not.)

Re Earth Leakage. Yes I think it would be similar. I have a lot of electronics in the home, so it makes sense if these could affect this. I'll do some testing and switch off as many as possible prior to grid coming back on.

I'll also mention the torque of connections/terminations. It would/should be easy for them to check the grid voltage following an outage. We have 3+ long outages a day, so I'll ask them to come in-between, and bring a meter with, which they can leave here for testing.

Wrt the grid code used. I have a feeling this was not set, or a default or junk code was set. I will ask the technician to confirm this with me and to ensure one appropriate to SA is used. (Indeed, our service is single phase 230V, 50Hz).

Thanks again for the feedback. I'll update here once the technician has been around. Hopefully with good news :)
 
Wonder if as your grid comes up the large variations are a problem. Maybe there is a way to delay going back on grid for a few minutes when grid power restored just to prevent this? Otherwise lower charging speed might work.
 
Thanks for the continued feedback on this!

We are still in comms and troubleshooting this with Tesla and local provider.

As you noted, when the grid returns, and due to the unreliability of South African power in general (which is magnified post load-shedding outages), the voltage/frequencies are all over the place.

From what Tesla are giving us feedback wise, this seems to be confusing the units switch overs.

i.e. Ideally if the grid goes offline, or if there is a problem with the grid (i.e. frequency dips), the Tesla would switch over and power the home and recognize this as a grid outage.

Tesla have been trying to accommodate the SA fluctuation with the frequency range settings and charging settings, and we have settled back on the 3.3 charging rate. The lower option does not give enough time to charge between the continuous outages experienced here, and the faster ones obviously cause the variance issues to be exacerbated, and the home's power is continuously switched on and off by the unit. Which is not ideal for electronics/anything.

Tesla have asked the local provider to purchase and install a new set of specialized wires, which are apparently far more sensitive, and may alleviate some of the issue by allowing the Tesla to pick up on the variances quicker.

As @neo1738 suggested, I had also previously asked Tesla if it would be possible to delay the Tesla charging process for 30 mins or 1 hour post grid return. They responded that this was not possible. So the lower charging + more sensitive wiring may be the best case scenario for now. (Unless of course I just go off grid completely, which is probably going to be the best bet here. The power situation in SA is degrading quickly).

We are awaiting these and I'll update here again once installed.

But for now the issue has been narrowed down to the voltage post outage, and inability to pick up on these in time/confusing unit.

Thanks again for the feedback.
 
@exsar Sorry about your troubles. There aren't many modern solutions to the large voltage and frequency variations that ensue with rotating blackouts and grid restoration in an overloaded environment.

In the past, things like motor generators were used to mechanically store energy, and to provide frequency stability for better ride through of frequency shifts and voltage sags. These were available in high power versions, but they are not particularly efficient, due to the motor and generator losses.

There are also device called ferroresonant transformers that can be used to stabilize the incoming voltage and frequency. Again, there are efficiency losses. I have used small ones >2kW, and I have no knowledge of whether they would work well with Tesla electronics.

Unfortunately, I agree with you that the recent, and not so recent, trend on power investment and reliability in SA is not good. Electricity seems to be an especially big political item there. (Not that it is politics free here, either. It definitely is, but people here seem to have some baseline beliefs on what constitutes a reliable grid.) That might make the fully off grid solutions more reliable and, unfortunately, more cost effective for you in the long run.

All the best,

BG
 
Sounds like it's the best you can get for now. Definitely recommend some solar in your life. Might help stabilize that power flow, also when off grid during day won't drain the battery as fast the 3.3 might be enough.
 
Hi Jason,
I would recommend solar as well, will keep the inverter on and charge the battery in the day time, which makes sense and you can stay off grid for longer too, plus like neo1738 says might help stabilize the power flow too once back on grid...
where in SA are you ? im from Sandton, but in the UK for the last 15 years lol ...
after a PW aswell, but rather second hand one as very pricey here