Testing outage with solar/batteries/generator

[h2ofun]

Well, decided to try a test of my solution before the next big storm hits Calif tonight.
For folks who follow me, I have basically two systems setup for my house wihere I have a 400 amp service with 2 200 amp subpanels.
I have 2 gateways, and two ATS for the generator wired in.

So the first thing I did was pull the two breakers to cut off power to the house. Then house did not lose power and the batteries worked fine.

I then turned off the 3 batteries on my one house gateway. The power went out in the house, and the generator did not start.
I then turned off the 4 batteries on my one garage gateway. The generator came on, I believe both ATS engaged, and I had power to both the house
and garage from the 22kw Honeywell generator.

I then went back and turned on all the batteries, the generator turned off, but my house was still dead. The GW for the garage after some time correctly came back up. But the house gateway never engage,d and the battery green lights never turned on.

I then called tesla powerwall support trying to figure out what was going on. The first person had me turn the grid back on and I had power to the house and garage. He told me something must be wrong with the wiring since the generator should have been able to charge the batteries. (He did tell me this works, but is not talked about. ) So I hung up thing okay, working and will write V3 electric with an issue.
I then looked at my phone and saw the house app still showed the grid not connected and running off the batteries. Not good. So I called back to powerwall support and talked to a different person. We first reset the gateway, no fix. We then shut of the grid breaker for 30 seconds, and turned back on. This got things working again. But, she said with my setup, with the generator with the ATS's, should be configured in a off grid setup, and this is different firmware and processes. But, since one seemed to work correctly, technically, she was not 100% sure what was going on. But she told me I clearly needed to get a V3 Electric expert involved to get to root cause, probably working in real time at my home with level 2 technical support on the phone with them.

So have no idea what the root cause solution will be since one gateway seems to be wired such that it worked, but the other did not. And with the comment that maybe it needs to be configured as an off grid install because of my generator with the ATS's used is unclear. But, glad I did some testing now.

The issue that I had never really thought about was lets say I lose power for a long time, and no real solar. By default the batteries will 100% drain to zero, unless I watch and turn off before this. If they get to zero, sounds like things may not turn back on automatically or correctly? So 99.9% of the time, power goes out, but comes back on soon enough that this concern is never thought about. Well, I am thinking about it now.

I just sent off a message to V3 Electric with the issue. Shall be interesting who they assign to this issue since my install is not your standard easy setup, but the support person told me I am not the only one, especially in California, she said lots of off grid installs they support.

Anyone else ever get a comment about the generator will charge the batteries from powerwall support?

 

[CrazyRabbit]

Seems like the generator start wire from the second transfer switch isn’t connected.
You ats is between your loads panel and the gateway, so you can’t charge from generator.
I suspect your Powerwall restarting issues was because you shutdown the Powerwall with the switch on the side. Next time just hit the breakers in the generation panel. Doing what you did seems to require a restart of the gateway. One way to do that is pull the data cable to the powerwalls (in grid out).

 

[Vines]

You get some interesting information when you call Tesla Support lol.

The reason I suspect things didn't function as expected is how you simulated the outage. You wanted to simulate draining the batteries but if the switch is turned off that means something else like an emergency or service needs to happen. Your signals were telling the powerwalls there was an emergency.

It sort of makes sense that just 1 of your ATS systems is connected to the generator, this is the easy way to wire things. As pointed out above only 1 of the ATS is sending a start signal to the generator. So in a grid outage situation, the generator would not start when the house battery system depleted, only starting when the garage powerwall system depleted.

No way in hell the generator is going to charge the batteries, assuming someone didn't make a mistake wiring things. Also, you certainly don't have an off-grid setup, those were just bad support comments.

Here's a question: when you do go off grid and the generator is powering things, what does your app say for BOTH gateways? Is either one of your Gateways able to read the generator output to the essential loads through the app? You can simulate the batteries dying much better in one half of your system by opening the breaker in the backup panel that feeds the ATS subfeed after turning off the main breaker.

It is not super easy to test this scenario, but truly turning off the main breakers for a long period of time would be informative. Let the batteries drain down naturally, maybe even turn off your solar input 100% to accelerate the process. Do this while the grid is up and reliable obviously so you don't get into trouble with dead batteries.

There are 2 ways to set up a system with a generator downstream and I do not know if one or both your Gateways is set up to know it has a generator downstream. If you set it up without knowing there is a downstream ATS, then the wake-up behavior when batteries are dead is automatic every hour starting at 9am.

If you install tell it has a downstream ATS then the wakeup behavior of the Powerwall batteries is manual. It requires you to manually isolate the Powerwall microgrid from the generator microgrid. This allows 2 microgrids to form and the batteries to independently recharge from the solar without the home load draining them down, after a few hours of PV and the batteries are charged with the generator still serving your loads, you reconnect the TEG to the generator feed and the generator ATS sees this as grid signal, turning off the generator and allowing the powerwalls and PV to 100% serve the loads again.

The issue and choice that you face is whether to set it up so either half system going down will trigger the generator.

After you know how each of your system is configured, you can understand what it is supposed to do based on manual or automatic wakeup.
Tell your installer to share with you "Powerwall 2 AC and Generator Backup with ATS" document, this explains how you have to turn off and on breakers in a low battery situation with manual wakeup. You basically waiti till the sun is shining and open the breaker feeding the ATS then trigger any enable switch in any one of the powerwalls to restart the microgrid so the batteries can recharge without the loads draining them down.

However it might be interesting if only one of your TEG has the Generator CTs, then one would be on automatic and one would be on manual wakeup lol.

This is actually the first time I have considered the issues here, as none of our other systems were setup this way. I am not totally sure what Tesla recommends regarding the 2 main questions:
1. Should both TEG be setup with generator CT's and therefore to manual wakeup.
2. Should the downstream ATS be setup so that loss of power at either ATS turns the generator on?
2a. The related question is should the 2 ATS be ganged so that both of them transfer together at loss of power at either subfeed location or should they be independent? This is probably more of a preference thing for the user, but an interesting thought.

I'll have to think more on the best recommendation for someone in your situation, and am very curious what the installer's input is.

EDIT for details about the Generator CT's vs setting downstream ATS in the commissioning wizard. The CT's only inform of power quantity, its the generator field in the TEG commissioning wizard that controls this.

 

[BGbreeder]

On question 2, why wouldn't you want the two ATS to be individually able to call for generator backup? (Especially in a scenario like @h2ofun's where the battery sizes are different)?
On question 2a, in addition to the different load/different storage issue, I can see that there might be equipment failure reasons for one ATS to need power and the other not, so not having the, ganged would seem desirable, don't you think?

Good luck with the storm tonight!

All the best,

BG

 

[Vines]

On question 2, why wouldn't you want the two ATS to be individually able to call for generator backup? (Especially in a scenario like @h2ofun's where the battery sizes are different)?

Because you are in an emergency, solar irradiance is low and are only using part of your house, and trying to be efficient with your generator use so as to not run out of propane. If you simply want to lose power as little as possible then you want either ATS to trigger the generator to startup.

On question 2a, in addition to the different load/different storage issue, I can see that there might be equipment failure reasons for one ATS to need power and the other not, so not having the, ganged would seem desirable, don't you think?

If the equipment were to fail, then hopefully someone can disconnect the signal from the broken side so it's not triggering the generator when the other side still has energy.

Good luck with the storm tonight!

All the best,

BG

Thasnks, woke up to a creek has diverted itself into my property and is trying to flood it. Luckily we are on a slope so instead its just washing across our property. I'll be glad if this is the worst of it.

Personally in H20's situation and installation, I'd probably have them setup as ganged, so if I wasn't paying attention I would get an early warning that half my house was out of power. Hopefully, in a prolonged outage, you plan to reduce usage and already were manually isolating the house for maximum duration of the battery and generator system.

I'm thinking a bit apocalyptic I admit, like a winter outage situation where you are snowed in or some other disaster means you can't get a refill of your propane.

 

[BGbreeder]

@Vines I think most generator owners greatly underestimate the amount of fuel that they need for any sort of extended outage. If avoiding that's apocalyptic thinking, I'm off the same mind. (Which is probably why I have backup generators and backup backup generators...)

I remember a cold snap in our area awhile back and the whole house generator folks were at the back of the l8ne for propane refills for weeks.

All the best,

BG

 

[h2ofun]

@Vines I think most generator owners greatly underestimate the amount of fuel that they need for any sort of extended outage. If avoiding that's apocalyptic thinking, I'm off the same mind. (Which is probably why I have backup generators and backup backup generators...)

I remember a cold snap in our area awhile back and the whole house generator folks were at the back of the l8ne for propane refills for weeks.

All the best,

BG

When I am using my generator, I ONLY turn one for an hour at morning, lunch and dinner. To run all the time would be nuts in so many ways. With my 500 gallon tank, I would be fine for a long time

 

[h2ofun]

Because you are in an emergency, solar irradiance is low and are only using part of your house, and trying to be efficient with your generator use so as to not run out of propane. If you simply want to lose power as little as possible then you want either ATS to trigger the generator to startup.

If the equipment were to fail, then hopefully someone can disconnect the signal from the broken side so it's not triggering the generator when the other side still has energy.

Thasnks, woke up to a creek has diverted itself into my property and is trying to flood it. Luckily we are on a slope so instead its just washing across our property. I'll be glad if this is the worst of it.

Personally in H20's situation and installation, I'd probably have them setup as ganged, so if I wasn't paying attention I would get an early warning that half my house was out of power. Hopefully, in a prolonged outage, you plan to reduce usage and already were manually isolating the house for maximum duration of the battery and generator system.

I'm thinking a bit apocalyptic I admit, like a winter outage situation where you are snowed in or some other disaster means you can't get a refill of your propane.

Man am I learning way too much. My issue all starts because I have a 400 amp service, into 2 200 amp subpanels.
And since Tesla does not have a 400 amp gateway, I was forced to break my batteries into two parts with two gateways. This they also messed up the generator from how I want to use it.

So just had a friend over who installs generators. Seems a 2 ATS setup has one the master, and other one the slave. Unless the master engages, the slave does not engage. All this makes sense if you have either no batteries, or all the batteries on one subpanel. Is only an issue in my case. Basically I have wired up two homes and want to share a single generator with these two houses.

So, this is pushing stuff. Vines, your challenge. Seems what I need is some type of controller such that both of my ATS's drive into this, meaning they are both masters, and the output goes to the generator. This way if either lost power, it only engages the ATS one that lost power, not both. Make sense? I sure hope I can find this has a technical solution.

 

[Mayer]

Way out of my depth here but enjoyed reading through this thread; down the CrazyRabbit hole, “if you will.”

 

[GregBallantyne]

I've got a similar question, but will ask it in a new thread.... this one doesn't really adress my situation....

 

[miimura]

Since @h2ofun ’s house logically looks like two houses, I would investigate how to configure the ATS units as if they were also for an independent house but had the generator start signal logically OR’d together. Either ATS asking for generator power would get it and each ATS would only cut over when the PowerWalls connected on that side could not power their loads.

 

[BGbreeder]

Since @h2ofun ’s house logically looks like two houses, I would investigate how to configure the ATS units as if they were also for an independent house but had the generator start signal logically OR’d together. Either ATS asking for generator power would get it and each ATS would only cut over when the PowerWalls connected on that side could not power their loads.

If one were going to adjust things, I think that there might be an opportunity to merge the forecasted weather and the desired generator working hours to perhaps optimize both generator loading (preferably high), and Powerwall charge/discharge. E.g. spool up the heat pumps while on generator power to heat / pre-cool the house, run electric stoves / dryers, etc.

There is an additional thought which is being able to parallel the generators to enable one generator to power both halves of the house while the other is being serviced, but not every generator is capable of synchronization and parallel power easily.

There are reams and reams of material posted and written on this for other applications (off-grid, true UPS, military, etc.)

All the best,

BG

 

[h2ofun]

Since @h2ofun ’s house logically looks like two houses, I would investigate how to configure the ATS units as if they were also for an independent house but had the generator start signal logically OR’d together. Either ATS asking for generator power would get it and each ATS would only cut over when the PowerWalls connected on that side could not power their loads.

From what I researched, the Generator cannot do this. One ATS much be the master, and the other the slave. So, if the slave runs out of batteries, I have to turn of the PW;s on the master, of the generator does not kick in, which powers my logically 2 homes.

 

[BGbreeder]

@GregBallantyne More here;

Whole home generator backup with Tesla Powerwalls

I'm working on a large residential home (1000-amp service) and the owner is requesting full generator backup. There will also be a 20 kW PV system and (4) Tesla Powerwalls. I'm looking for the best solution to integrate these two systems. The owner does not want a manual transfer switch to...

forums.mikeholt.com

 

[sunwarriors]

@GregBallantyne More here;

Whole home generator backup with Tesla Powerwalls

I'm working on a large residential home (1000-amp service) and the owner is requesting full generator backup. There will also be a 20 kW PV system and (4) Tesla Powerwalls. I'm looking for the best solution to integrate these two systems. The owner does not want a manual transfer switch to...

forums.mikeholt.com

People are really just better off going with Enphase if this is a requirement. It already works and there are probably a fair amount of installs that do this out there. That's the summary of that whole thread too.

It's also supported vs. a home hacked solution that Tesla won't help you on so the ideal thing is just use the generator to top off the batteries for night so it's quiet and run the generator an hour during the day to not disturb anymore. This and V2H (should be this year) is my plan if I ever had spare $$ to throw at it.

 

[BGbreeder]

People are really just better off going with Enphase if this is a requirement. It already works and there are probably a fair amount of installs that do this out there. That's the summary of that whole thread too.

It's also supported vs. a home hacked solution that Tesla won't help you on so the ideal thing is just use the generator to top off the batteries for night so it's quiet and run the generator an hour during the day to not disturb anymore. This and V2H (should be this year) is my plan if I ever had spare $$ to throw at it.

I agree that the Enphase route is a much superior version for generator integration.

It will be interesting to see how V2H/V2G shakes out.

 

[mikesm]

I am looking forward to the Solaredge bidirectional EV charger that is supposed to ship this year. It DC charges the car battery direct from solar, and powers the house through the solar inverter from the DC bus if Solar is inadequate. This seems like an easy way to do load shifting through a V2H equipped vehicle. I use a genset for backup power, do don't worry about that issue from the batteries. And no panel mods - it plugs into the DC bus.

The price on V2H vehicles this year may make the economics finally work here in PGE land. The coming GM EV 1LT equinox that comes with 80 kWh of battery (GM looks like they gave up on 2 battery SKUs) may be the best candidate, as much as I hate GM's idea of eventually charging monthly for the infotainment system. This would be a 3rd car for us (we have 4 kids) and when the kids are out of the house it can be a permanent battery for loadshifting.

 

[Grayson73]

I wish Tesla would come up with something like that so that we can do V2H. Right now I use a long extension cord and power strips

 

[mikesm]

I wish Tesla would come up with something like that so that we can do V2H. Right now I use a long extension cord and power strips

I think it might cut into Powerwall sales. I assume in CA they are selling a lot less of those as the number of solar installs have come down thanks to NEM 3.0. I think the margin on the PW's is not insigificant. It also will increase the number of cycles on the battery, driving more service costs, but as long as no one else had a competitive EV, why should they take those hits?

The discounting and margin hits they are taking now show they can't ignore that functionality, so they announce a date in the future when it will show up to try and blunt the response, but I assume they'll have a decent solution whenever they decide they have to have one.