Inverter shutting down during "off-grid" with Powerwalls at 51%

[AAinSoCal]

I have 3 Powerwall 2s with a Gateway 2 that have been running for about 2 weeks. This is a third party install as I already had solar. Today I tried the "Go Off-Grid" button on the app, which only became functional for me a couple of days ago. The batteries were at 51%, but going off grid immediately shut down my solar inverter with an "AC Frequency Too High" error. I checked the frequency at an outlet with a multimeter and it was floating around 62 Hz.

I called Tesla and was told this was expected behavior and that the batteries will only attempt to charge from solar once they go below 40%. This was the first I'd heard of anything like this. Can anyone confirm whether this is really the case?

Note that I did email Tesla ([email protected]) last night to request a reduction in off-grid frequency when the batteries are near full. I tried going off grid a couple of nights ago when I first got the "Go Off-Grid" button in the app. The batteries were then near 100% (storm watch), and my UPSs and a some lights went nuts. It was night, so I didn't expect anything from solar. I don't know if they adjusted something at my request and introduced a new problem.

I any event, I'm hoping to understand if the behavior I'm seeing is normal or if I should bug Tesla some more. I did email support again, describing the situation and asking for some guidance/help.

 

[jjrandorin]

I called Tesla and was told this was expected behavior and that the batteries will only attempt to charge from solar once they go below 40%. This was the first I'd heard of anything like this. Can anyone confirm whether this is really the case?

I havent heard that before, and that doesnt match anything I have read, or heard about here, either.

The general consensus on "when solar is shut down when off grid with powerwalls" is (in general terms) somewhere around 90-95%. Some inverters can ramp down, and some (like mine) simply are "on or off". In my specific case, my inverters (2) are from a 2015 solar city install, and are a brand called "ABB". They do not have curtailment, so are either on or off.

If I go off grid (either on my own, or because of something out of my control) and my powerwalls are above 94-95% the frequency will raise to what it is now set to on my install (62hz) and force my inverter off. Once the powerwalls drop below about 93%, my inverter will come back on.

40% is not a number I have ever heard, and that sounds like an inexperienced person simply trying to get you off the phone, at least to me.

Since you already have PTO for your solar, the powerwalls require a separate PTO, HOWEVER most of us in that specific situation (powerwall only install, installed onto pre existing, already "PTO'ed" solar) ran our powerwalls after passing the AHJ inspection. This shouldnt be an issue with PTO, unless tesla has applied some setting to your setup we are unaware of (Did you get powerwall 2 or powerwall+? I am assuming powerwall 2 since you had existing solar).

I would test one more time (so there is info in the logs for tesla to review) and then call back again and hopefully get another rep.

 

[AAinSoCal]

40% is not a number I have ever heard, and that sounds like an inexperienced person simply trying to get you off the phone, at least to me.

Since you already have PTO for your solar, the powerwalls require a separate PTO, HOWEVER most of us in that specific situation (powerwall only install, installed onto pre existing, already "PTO'ed" solar) ran our powerwalls after passing the AHJ inspection. This shouldnt be an issue with PTO, unless tesla has applied some setting to your setup we are unaware of (Did you get powerwall 2 or powerwall+? I am assuming powerwall 2 since you had existing solar).

I would test one more time (so there is info in the logs for tesla to review) and then call back again and hopefully get another rep.

Thanks very much. I suspected as much about the phone rep. I have PTO for both solar (years ago) and Powerwalls (a few weeks ago; I had them off between installation and PTO per my installer's instructions). I'm guessing there's a configuration error of some sort. I tried testing twice within 30 minutes, but I'll give it another shot later in the day. I'm also planning to test at below 40%, where I expect exactly the same thing to happen, just so I have that on record.

 

[jjrandorin]

Thanks very much. I suspected as much about the phone rep. I have PTO for both solar (years ago) and Powerwalls (a few weeks ago; I had them off between installation and PTO per my installer's instructions). I'm guessing there's a configuration error of some sort. I tried testing twice within 30 minutes, but I'll give it another shot later in the day. I'm also planning to test at below 40%, where I expect exactly the same thing to happen, just so I have that on record.

Let us know how it comes out. I imagine your testing under 40% would be the same as above, as well.

 

[AAinSoCal]

Let us know how it comes out. I imagine your testing under 40% would be the same as above, as well.

I just tried turning off my service disconnect breaker (i.e. off-grid for real, not through the app). The Powerwalls kicked in immediately and the solar stayed on. Measured frequency was around 59.7 Hz. I'm guessing behavior isn't supposed to be different between a real (or at least manually introduced) outage and one simulated by the app, but is seems to be for me. Oh well, at least I've got some reason to believe I'll be good in a real emergency. I'll keep bugging Tesla though.

Another pretty basic question: Going back on-grid from the app takes some 10s of seconds. Going back on-grid for real, by which I mean flipping the breaker off and back on, takes 5-7 minutes before the Gateway recognizes the grid. This is the 4th time I've tried the breaker thing, and that behavior has been consistent. Is that what others experience too?

Thanks again from a Powerwall newbie.

 

[jjrandorin]

Going back on-grid for real, by which I mean flipping the breaker off and back on, takes 5-7 minutes before the Gateway recognizes the grid. This is the 4th time I've tried the breaker thing, and that behavior has been consistent. Is that what others experience too?

Yes, thats normal. The wave pattern has to synchronize with the grid, and there is some default value of time that the systems are setup to do that. From memory I believe that time is 5 minutes.

Regarding your other point, it sounds like, if you physically turn off your main breaker (physical disconnection) it behaves as you expect, but if you do a "logical disconnection" by going off grid in the app, it doesnt?

The off grid in the app is fairly new (a couple months or so). I have only tried it a couple times, after setting it up. I have a gateway 1 (the grey box one) not the gateway 2 (looks like a mini powerwall) that you may have.

I would also recommend testing it one more time when your powerwalls are around 90% or so, and throwing your main breaker (be prepared for a power blip during switchover if your powerwalls are not already powering your home).

 

[AAinSoCal]

Yes, thats normal. The wave pattern has to synchronize with the grid, and there is some default value of time that the systems are setup to do that. From memory I believe that time is 5 minutes.

Thanks. This is good to know.

Regarding your other point, it sounds like, if you physically turn off your main breaker (physical disconnection) it behaves as you expect, but if you do a "logical disconnection" by going off grid in the app, it doesnt?

Yes, this is exactly what seems happening.

The off grid in the app is fairly new (a couple months or so). I have only tried it a couple times, after setting it up. I have a gateway 1 (the grey box one) not the gateway 2 (looks like a mini powerwall) that you may have.

I do have a gateway 2.

I would also recommend testing it one more time when your powerwalls are around 90% or so, and throwing your main breaker (be prepared for a power blip during switchover if your powerwalls are not already powering your home).

Will do! Thanks again for all the help.

 

[aesculus]

Another pretty basic question: Going back on-grid from the app takes some 10s of seconds. Going back on-grid for real, by which I mean flipping the breaker off and back on, takes 5-7 minutes before the Gateway recognizes the grid. This is the 4th time I've tried the breaker thing, and that behavior has been consistent. Is that what others experience too?

As @jjrandorin stated this is normal. Its to avoid what the utilities call "momentary faults'. These are faults like trees brushing against power lines that may trip protective devices but get restored in a few seconds or minutes and don't require a 'truck roll'. In fact utilities are not dinged the same way for these type of faults as they are for the extended faults.

 

[Steve2498]

To the OP, did you get a resolution to your issue Of the inverters being shut dow?

I have a new installation which is doing the same thing. When the installer tested off grid from his app (that option doesn’t yet show in my app), the powerwalls shift the frequency up to ~65hz and it stays there, shutting down the inverters. The SOC of the PW was ~30% at the time.

The installer said a momentary frequency shift is expected when going off grid but the PWs should go back to 60hz fairly quickly allowing the inverters to operate normally.

He is now working with Tesla to resolve this.

 

[RKCRLR]

It's worth mentioning that my solar shuts down for about 5 minutes once even a momentary power interruption occurs. So you need to wait at least 5 minutes to see if the solar starts charging the Powerwalls.

 

[aesculus]

It's worth mentioning that my solar shuts down for about 5 minutes once even a momentary power interruption occurs. So you need to wait at least 5 minutes to see if the solar starts charging the Powerwalls.

I would expect that if you are taking power from the grid. But what happens if your PWs are supplying power to the home such as peak rate times in Self Powered or Cost Savings?

 

[sorka]

Temperature could be a factor. I would not be surprised if recent firmware changed just how much the PWs are willing to accept off grid in lower temperatures. The last time I tested this by throwing the breaker was this summer and the PWs output 59.7 Hz all the way up to about 98% SOC.

But this is Tesla. They could screw us all with any random software update or remote config change should they decide it's in their financial interests.

 

[RKCRLR]

I would expect that if you are taking power from the grid. But what happens if your PWs are supplying power to the home such as peak rate times in Self Powered or Cost Savings?

Anytime there is a power interruption my solar resets. Doesn't matter where the power is going or coming from.

 

[AAinSoCal]

To the OP, did you get a resolution to your issue Of the inverters being shut dow?

I just tested again yesterday and the inverter did not shut off. This was at about 90% SOC. I then let the powerwalls charge to 99% and tried a second time. The inverter did shut off that time. Note that these tests were using the app to go off grid rather than physically shutting off service at the breaker, which has always behaved correctly for me. FYI, the line frequency from the batteries was about 59.9 Hz during the first test and about 64 Hz during the second. I’m planning to bug Tesla again about lowering that 64, but that’s less of a priority.

A thought I had about my earlier trouble was that the batteries were then in an active Storm Watch condition. Maybe this, combined with the software (ie. triggered from the app) grid disconnect, put me in some weird state.

 

[Steve2498]

I'm updating this in the hopes it can help someone push back on misinformation (from tesla support) about how these systems interact with inverters when off grid. Since my installation two months ago my independent installer, tesla and I have been going around in circles trying to fix the powerwalls shutting down my inverters when off grid.

Like the OP, Tesla started off saying it was because at 80%, the batteries were at too high of a SOC; so I did another test at 50%, they told me still too high, it needs to be really low, like 30% before the frequency drops back to normal and the inverters start up again. I'm thinking that is BS but what do I know so I try again at 25% - still doesn't work.

Then Tesla says "oh it is because the batteries are too cold (its like 40F outside). More head scratching and proving them wrong. They did some more troubleshooting and changed a setting that had something to do with higher than normal impendence on my system. Testing showed it still didn't work.

A week later, the installer is back for a site visit but magically everything works perfectly - the installer doesn't have a clue what changed, maybe Tesla changed something in the background that we don't know about!!!???

So for those that are wondering, here is the behavior I observe on my system which has 2 sets of panels, one with an old Sunnyboy inverter (can't ramp up or down production) and a newer set of panels with microinverters which can ramp production.

In an off grid situation, I get full solar production (in my case ~7.8kW this time of year) up to ~97% SOC. Then the Sunnyboy drops offline leaving me with ~4kW of solar production. At 98% SOC, the microinverters start ramping down production to ~2kW then drop offline. After about 10 minutes (depending on the load) the microinverters ramp back up to ~4kW and then back down to 0 over about 10 more minutes. All the while the Sunnyboy just stays off line until I'm back on the grid or when the SOC drops below ~97%.

Hope this helps.

 

[zƬesla]

@Steve2498 – I have 2 SMA SB's (7.0 & 7.7) and originally had 2 PWs. When first installed, I noticed the system shutting down when it got pretty sunny. Took a while to pinpoint the issue due to bad information from Tesla and its third-party certified installer. Bottom line, 2 PWs was not sufficient to handle the charge on sunny days causing the TEG telling the inverters to shut down, and the installer ended up putting in another PW at their cost to resolve the issue. Our SB's have a ramp down capability, but between the PV installer not knowing enough about it and my wanting a working solution based on the cost/specs proposed by the Tesla installer, we ended up not enabling it. If I ever need the system serviced, I'll get a competent installer and may have them enable the feature to eek out solar a little longer during an outage.

 

[ptdusn]

@Steve2498 – I have 2 SMA SB's (7.0 & 7.7) and originally had 2 PWs. When first installed, I noticed the system shutting down when it got pretty sunny. Took a while to pinpoint the issue due to bad information from Tesla and its third-party certified installer. Bottom line, 2 PWs was not sufficient to handle the charge on sunny days causing the TEG telling the inverters to shut down, and the installer ended up putting in another PW at their cost to resolve the issue. Our SB's have a ramp down capability, but between the PV installer not knowing enough about it and my wanting a working solution based on the cost/specs proposed by the Tesla installer, we ended up not enabling it. If I ever need the system serviced, I'll get a competent installer and may have them enable the feature to eek out solar a little longer during an outage.

I have been having an issue lately of when the batteries are at 100% and the PVs are putting out a high kW, (6.5-7), I get a "load meter" error on my home indication and the display says the house is at a negative kW (-1.2kW), and the solar is going to the grid. I have to shut the whole system down for a few minutes in order to get it reset.