Potential Storm Watch Issue

[DHevey]

About a month ago, while I was out of town, we had several severe storms. I lost a router, an ethernet switch, and even one of my inverters. All were behind my Powerwalls, and I thought it was odd that equipment behind the Powerwalls could be damaged. I have six Powerwalls, so my protected circuits rarely see the grid.

Two Thousand dollars in repair costs later, today we are having another severe storm, and I think I understand what happened. In today's case, my Powerwalls were charged to 99%. We went into Storm Watch, and the system diverted grid power to power the home. Under this scenario, any severe surge in power can now get past the gateway and damage equipment, whereas, without Storm Watch being activated, the system would be running off the Powerwalls as usual and would be isolated from surges. I have turned off Storm Watch because of this.

I think Storm Watch is useful if you need to charge your Powerwalls prior to an event that could result in a grid outage, but when it's active in the middle of a severe storm, I think it can create its own problems. Am I missing anything here?

 

[Zinc_Saucier]

Even when the house is being powered by the PowerWalls, it’s not isolated from the grid. I’m not sure how that would impact surge protection at all.

 

[DHevey]

I realize that the Powerwalls get their timing from the grid, but can you explain how circuits being powered by Powerwalls are not isolated from the grid?

 

[jjrandorin]

I have six Powerwalls, so my protected circuits rarely see the grid.

These are not isolated that way. There was another thread here where the member said something like "I want to use 100% clean energy from my powerwalls", and I was trying to explain that that "is not a thing".

Here is the post I made in that thread to try to explain. TL ; DR -- These systems are not wired in such a way that all power from the grid goes to your batteries, and you batteries are 100% powering your home at all times. There is no "protection" for your home provided by the tesla gateway. Its not a whole home surge protector, etc.

No, the battery powers both critical and non critical loads when the grid is up. There is no "wiring error" in your system using battery power to power all loads when the grid is up.

You were talking about "100% clean energy" and that isnt what happens. The system is not designed to run "ALL POWER' through the batteries. There is a difference in running all power through the batteries, and the batteries being able to provide power to all loads. A data center or hospital (something that can not tolerate even a little bit of switch over time to battery backup) will be setup in such a way as all power, at all times comes from the batteries, and the batteries are re filled from "sources".

Our home systems are not setup that way, and that doesnt have anything to do with the fact that the battery is setup to power loads.

An analogy would be if I was standing with you and your family, and said "I can give you some muffins for your family", I could hand you, your significant other, and any children you have each a muffin, and I would have given you all muffins.

Or, If you said "no, you will give ME all the muffins and I will hand them to my family", in this case I hand you the muffins and then you hand them to your family. In both cases they end up with the muffins, but in one case I gave them out myself (to all the loads), in the other case I handed them all to you, and you handed them out (to all the loads). In both cases all the loads got muffins.

You keep saying its mis wired, and I am telling you its not mis wired, its designed to operate that way. "Mis wired" means "wrong" and its not wrong, you just dont want it that way for <reasons> and thats up to you but its not "wrong".

In any case, I am obviously failing at explaining this, so I will again just wish you good luck with it, and encourage you to continue to find out from your installer if your specific install can be setup to remove the AC since it appears that is what you want.

 

[BGbreeder]

Conceptually, Powerwalls are "Tee"d off from the grid supply can push or pull power as needed.

I suspect you would benefit from a whole house surge protector at a minimum, and depending on your local topography lightning rods.

All the best,

Peter

 

[DHevey]

I have two 200 Amp Panels. One is connected to the gateway, and one is not. The one that is not connected to the gateway does not receive power from the Powerwalls - ever. Yes, the unprotected loads receive excess solar when it is available, but the unprotected loads remain on the grid-side of the system and never see the Powerwalls.

I never suggested that the gateway was a surge protector. I suggested that it is an isolator, as in: the energy coming from the Powerwalls is directed solely at the protected circuits and is isolated from the grid.

 

[jjrandorin]

I suggested that it is an isolator, as in: the energy coming from the Powerwalls is directed solely at the protected circuits and is isolated from the grid.

I am fairly sure that this is not the case. There is nothing "isolated from the grid" on those circuits. If you set the powerwalls to 100% backup (for example) those loads would still be powered from the grid, as long as you were not in a power down situation.

 

[Zinc_Saucier]

The one that is not connected to the gateway does not receive power from the Powerwalls - ever. Yes, the unprotected loads receive excess solar when it is available, but the unprotected loads remain on the grid-side of the system and never see the Powerwalls.

Are you sure about this? I would think that there would be a set of CTs wired to the other 200A panel so the Gateway could report accurate consumption data. Assuming that you aren’t running at 100% backup, do you always see power flowing from the grid when solar is unable to cover the entire house load?

I don’t have a backup load panel, and only a single 200A service, but the powerwalls should be able to “push power” to the loads that aren’t backed-up when the grid is up.

 

[Vines]

I have two 200 Amp Panels. One is connected to the gateway, and one is not. The one that is not connected to the gateway does not receive power from the Powerwalls - ever. Yes, the unprotected loads receive excess solar when it is available, but the unprotected loads remain on the grid-side of the system and never see the Powerwalls.

I never suggested that the gateway was a surge protector. I suggested that it is an isolator, as in: the energy coming from the Powerwalls is directed solely at the protected circuits and is isolated from the grid.

If you can see your whole home usage, then the powerwalls can backfeed power into your main service panel fro one main breaker to the other and use battery energy to self consume both backup and non-backup loads. Whether or not you will consume this power depends on the settings in your app.

As fas as the gateway and the backup loads, unless you "go off Grid" or there is a power outage and your gateway opens its contactors your equipment is still subject to line surge. I hope that as part of that $2000 repair, you installed a high-quality whole home surge protector! As pointed out above, the powerwalls and PV are essentially a T shaped connection with your loads, Grid, and generation panel all being points of the T. Line surges when the gateway has its contactors closed are felt by all equipment. Even if the Gateway were in an open state, it has sensitive line sensing circuits which can get fried by a surge.

 

[DHevey]

I don't see my whole home usage - The Tesla system only sees and reports what is behind the gateway, which are my protected loads. Unprotected loads are monitored independently with a Sense unit. There is no Powerwall energy being fed to unprotected loads - ever. That would be self defeating. It is essentially configured as if there are two homes, one with solar and six Powerwalls, and one with neither, one with a Tesla gateway, and one without. As far as the gateway is concerned, the unprotected loads could be at my neighbors house.

So, in "self consumption" mode, my protected loads bounce back and forth between PV consumption and Powerwall consumption, except for the rare occasions (Less than fifteen days per year) when the Powerwall SOC is below my threshold setting, and on those rare occasions, my protected loads see and use the grid.


Q: Assuming that you aren’t running at 100% backup, do you always see power flowing from the grid when solar is unable to cover the entire house load?

A: I only see power flowing from the grid when (solar + Battery) are unable to cover my protected loads.


I hope this explains why it is problematic that Storm Watch forces my protected loads to see the grid during severe lightning events, even though my Powerwalls are charged to 99% (Most storms occur later in the day when the Powerwalls are fully charged, even in self-consumption Mode). I have surge protectors on each of my panels, but there is no surge protector in the world that can protect under all scenarios.

 

[schettj]

I suppose you could "go off grid" to protect the powerwall backed circuits during a storm. Then go back on grid after the storm passes.

 

[jjrandorin]

I don't see my whole home usage - The Tesla system only sees and reports what is behind the gateway, which are my protected loads. Unprotected loads are monitored independently with a Sense unit. There is no Powerwall energy being fed to unprotected loads - ever. That would be self defeating. It is essentially configured as if there are two homes, one with solar and six Powerwalls, and one with neither, one with a Tesla gateway, and one without. As far as the gateway is concerned, the unprotected loads could be at my neighbors house.

So, in "self consumption" mode, my protected loads bounce back and forth between PV consumption and Powerwall consumption, except for the rare occasions (Less than fifteen days per year) when the Powerwall SOC is below my threshold setting, and on those rare occasions, my protected loads see and use the grid.


Q: Assuming that you aren’t running at 100% backup, do you always see power flowing from the grid when solar is unable to cover the entire house load?

A: I only see power flowing from the grid when (solar + Battery) are unable to cover my protected loads.


I hope this explains why it is problematic that Storm Watch forces my protected loads to see the grid during severe lightning events, even though my Powerwalls are charged to 99% (Most storms occur later in the day when the Powerwalls are fully charged, even in self-consumption Mode). I have surge protectors on each of my panels, but there is no surge protector in the world that can protect under all scenarios.

Its not "stormwatch forces your protected loads to see the grid". Its "your protected loads are also connected to the grid any time your home is actually on grid, whether stormwatch is on or not".

 

[travwill]

I am fairly sure that this is not the case. There is nothing "isolated from the grid" on those circuits. If you set the powerwalls to 100% backup (for example) those loads would still be powered from the grid, as long as you were not in a power down situation.

If the grid goes down. They literally in the gateway disconnect physically so I’d say in that scenario they are isolated. Not if precharging for an event though.

 

[BGbreeder]

If the grid goes down. They literally in the gateway disconnect physically so I’d say in that scenario they are isolated. Not if precharging for an event though.

And you think the gateway knows that the power is up how?

Yup. It is connected to current transformers so it can monitor the presence and voltage of the grid. (Middle right side of your Gateway 2) A spike is going to induce even higher voltages in the CTs, likely leading to a plasma arc back to your side of the gateway, and plasma is a great conductor of electricity.

The gateway is always electrically connected to the grid, and to make matters wore, even if your loads are disconnected, there is only a small air gap in the main relay between your home circuits and the grid which will be jumped in the thousands of volts range. (Details of the electrode shape, sharpness, and random things like humidity affecting the actual voltage for the air gap arc)

The gateway is designed to switch off the grid after some number of cycles being absent, I.e. a hundredth to tenths of a second at best. A whole house surge protector is designed to clamp voltage spikes in nanoseconds, as in billionths of a second, limiting both the energy, and the time that your sensitive home devices are exposed.

The gateway is not an isolation device in the sense of isolating from voltage surges, spikes, or lightning strikes.

This has been discussed at length in other threads.

I don't understand why people who have tens of thousands of dollars invested electronic devices, EVs, and appliances, not to mention solar arrays and batteries, are so resistant to installing whole house surge protectors. If you have an isolated, or otherwise exposed home, I would certainly add a lightning rod system.

All the best,

BG

 

[DHevey]

You sound like you have a lot of knowledge of how the system works. I also have a lot of knowledge of how the system works. My reason for starting this thread was to comment on the fact that, when in Storm Watch mode, the system automatically decides to feed grid power to the critical loads during a severe thunder storm, regardless of SOC on the batteries, which, in my case, was 99% charged. There is no fool proof system that will suppress lightning under every situation, so it doesn't seem wise to promote a connection to the grid when it is unnecessary (Because the Powerwalls are at 99% and are fully capable of handling the load on their own). The intent of Storm Watch Mode is to use the grid to charge batteries that may be in a less than optimal SOC at a critical time. That was not the case in my situation. I was fully charged and happily running on battery during a severe storm when the system decided to power my critical loads from the grid - NOT to charge the batteries. When this happened a month ago, I lost several pieces of equipment on the critical load side, despite having surge suppression and a dedicated UPS, and I don't think this would have occurred if I had simply continued to run on battery, as I do every day in Self Powered mode. I hope that provides more clarity.

 

[morph3ous]

I think what everyone is saying is that even if you were on battery the surge still would have gone through. So it would not have made a difference. If you manually threw your main disconnect and therefore the grid connection was severed, sure. Otherwise the powerwalls are line interactive just like your solar inverters and being on battery power would not stop a surge from coming through.

 

[schettj]

I think what everyone is saying is that even if you were on battery the surge still would have gone through. So it would not have made a difference. If you manually threw your main disconnect and therefore the grid connection was severed, sure. Otherwise the powerwalls are line interactive just like your solar inverters and being on battery power would not stop a surge from coming through.

Would "Go off grid" setting have disconnected / isolated the system?

 

[Vines]

Would "Go off grid" setting have disconnected / isolated the system?

Go off grid would have isolated the loads but the voltage sensing equipment in the Gateway is still exposed to line voltages and surges.

If the breaker feeding the TEG was turned off, then the TEG would not see the same voltage surges.