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PowerWall Cold Start without Grid Power

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I'm guessing the terminals on the gateway are for when the Powerwalls have no reserve left. According to this thread, the Powerwalls will shut down overnight when they reach 5% charge so they have enough to restart in the morning. According to @MorrisonHiker, the part that didn't work was having the Powerwalls start charging again after restarting, perhaps because of the cold temperature. They did start recharging from solar, though, so presumably if conditions were right it would have worked.
Yeah, we saw our Powerwalls shut down when they got down to 5% after powering the house for the first 24 hours of a 46 hour outage.. They kept trying to start back up on the second day of the outage but they kept setting the frequency to 66 Hz. That caused the solar system to shut off repeatedly throughout the day and prevented them from running for more than a half hour or so. Tesla came out afterwards and updated the firmware on the inverters. They did a test and things worked well but the Powerwalls were way above 5%. I need to do another grid outage test with the Powerwalls down to 5% when it is cold to see if the problem has been resolved. One of the techs thought the 66 Hz might be the Powerwalls trying to stay warm but since others were having frequency issues before 1.37.1, I'm thinking the temperature wasn't the problem. I'll try a grid outage next weekend to see if things work as expected.
 
Yeah, we saw our Powerwalls shut down when they got down to 5% after powering the house for the first 24 hours of a 46 hour outage.. They kept trying to start back up on the second day of the outage but they kept setting the frequency to 66 Hz. That caused the solar system to shut off repeatedly throughout the day and prevented them from running for more than a half hour or so. Tesla came out afterwards and updated the firmware on the inverters. They did a test and things worked well but the Powerwalls were way above 5%. I need to do another grid outage test with the Powerwalls down to 5% when it is cold to see if the problem has been resolved. One of the techs thought the 66 Hz might be the Powerwalls trying to stay warm but since others were having frequency issues before 1.37.1, I'm thinking the temperature wasn't the problem. I'll try a grid outage next weekend to see if things work as expected.
David, the 66Hz should only be to shut the inverters down when the PWs are full, right? And the other question of course is do you need 66 or should yours be adjusted down to putting out 63? I’ve not done the same test on my new install yet to see if my UPSes fail with the 66 signal.

No idea why PWs would be altering/raising frequency at low power levels at all. You’d think they would want max PV to charge up.
 
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David, the 66Hz should only be to shut the inverters down when the PWs are full, right? And the other question of course is do you need 66 or should yours be adjusted down to putting out 63? I’ve not done the same test on my new install yet to see if my UPSes fail with the 66 signal.

No idea why PWs would be altering/raising frequency at low power levels at all. You’d think they would want max PV to charge up.
Yeah, that was a few months back so hopefully the software issues have been resolved. It didn't make sense to us and was quite frustrating on the day after the blizzard because it was totally sunny out and we cleared off all the panels but couldn't recharge fully or power the house. We should've been able to stay powered indefinitely but the on/off 66Hz cycle went on all day.
 
David, the 66Hz should only be to shut the inverters down when the PWs are full, right? And the other question of course is do you need 66 or should yours be adjusted down to putting out 63? I’ve not done the same test on my new install yet to see if my UPSes fail with the 66 signal.

No idea why PWs would be altering/raising frequency at low power levels at all. You’d think they would want max PV to charge up.
I forgot to mention we will try the test next week and contact Tesla if we still have a problem with the 66 Hz. Once we confirm that issue had been fixed, we'll have to try it down at 5% in the cold again.
 
This may have already been discussed, but it seems that the Gateway may know the type and brand of inverters if configured properly by the installer. Has anyone watched an installer to know whether the specific inverter details are entered during the initial setup?

I have two 7 year old SunnyBoy inverters and in the daytime grid outage test I performed a few weeks ago with PWs charged to 100 percent, the frequency was raised to no more than 62.8 Hz during the test and that did shut the inverters down. APS and Cyberpower UPS devices were not affected by the increased Hz. FYI, the Hz I observed was on the UPS device displays so I don’t know how accurate that is.
 
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Cold temperatures would also affect the battery’s ability to take a charge. It may be that the Powerwall decided to shut the solar down because it was getting more power than it could handle because the batteries were cold.
Interesting point. For the 63/66 Hz signal is there any level between on and off? You’d hope they could take some power until warm and then go full throttle. You’d also hope Tesla would know that. :D
 
Interesting point. For the 63/66 Hz signal is there any level between on and off? You’d hope they could take some power until warm and then go full throttle. You’d also hope Tesla would know that. :D

Yes, some inverters support this called "ramp down" where frequency between 60.5hz and 63.0hz will reduce the inverter % linearly and may be configured. I was just informed my Enphase IQ6 inverters support this https://enphase.com/sites/default/f...Considerations-AC-Coupling-Micros-Battery.pdf


"IQ Microinverters can gradually curtail power output based on the grid or microgrid AC frequency. This is often referred to as frequency / watt (frequency-based power control), or over frequency power limit. IQ Microinverters back off maximum power point voltage to reduce AC power output, based on the AC frequency. This causes no damage to the microinverters.

Modern battery-based inverters have the ability to gradually change their frequency when operating in off-grid mode when the batteries are reaching a full charge. When this option is enabled on the grid-forming, battery-based inverter, you can set the IQ Microinverters to gradually decrease and increase power output accordingly."
 
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Yeah, that was a few months back so hopefully the software issues have been resolved. It didn't make sense to us and was quite frustrating on the day after the blizzard because it was totally sunny out and we cleared off all the panels but couldn't recharge fully or power the house. We should've been able to stay powered indefinitely but the on/off 66Hz cycle went on all day.

Out of curiosity what is the maximum output of your solar inverters and how many Powerwalls do you have? I have an 8.6kw array but the microinverters are downsized to about 6.6kw. Since the Powerwall inverter's max sustained value is 5.0kw on a sunny day where the solar microinverters are maxed the Powerwall will shut them down to reduce the input below the inverter maximum to protect it, even if the battery needs to charge.

For inverters such as mine the Powerwall can reduce the maximum power from the array (see above) however it takes a moment for this to happen so I've seen the "see-saw" effect you mentioned earlier during an grid outage test I did on a very sunny day. In that test my Powerwall took about 10 seconds to kick in as it took a moment for the inverters to catch on to reduce their power output.
 
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This may have already been discussed, but it seems that the Gateway may know the type and brand of inverters if configured properly by the installer. Has anyone watched an installer to know whether the specific inverter details are entered during the initial setup?
.

I watched my installer do the configuration. It does ask what make and model inverters you have, presumably to know how to shut down and start if necessary/ It also asked for the max output.

Why doesn't somebody simply call support and ask how to do a cold start? Is this like the old old days with the phone company, they won't give out any technical info , so you don't mess with the equipment ? IMO, it would be good to know in advance of a power emergency how it works.
 
Is this like the old old days with the phone company, they won't give out any technical info , so you don't mess with the equipment ?
Yes, every company today still does that. Toyota, GM, Tesla, etc. Google, Apple (for all their tech products), etc. It only matters when that company is also monopoly and using that weight to stop competition.

Our current lifeline to fight that is Magnuson–Moss Warranty Act. Recently, it disabled the tampered-label-expires-warranty silliness.
 
Out of curiosity what is the maximum output of your solar inverters and how many Powerwalls do you have? I have an 8.6kw array but the microinverters are downsized to about 6.6kw. Since the Powerwall inverter's max sustained value is 5.0kw on a sunny day where the solar microinverters are maxed the Powerwall will shut them down to reduce the input below the inverter maximum to protect it, even if the battery needs to charge.

For inverters such as mine the Powerwall can reduce the maximum power from the array (see above) however it takes a moment for this to happen so I've seen the "see-saw" effect you mentioned earlier during an grid outage test I did on a very sunny day. In that test my Powerwall took about 10 seconds to kick in as it took a moment for the inverters to catch on to reduce their power output.
Our solar system is 16.575 kW but we our inverters add up to 18 kW. We currently have 3 Powerwalls.
 
Our solar system is 16.575 kW but we our inverters add up to 18 kW. We currently have 3 Powerwalls.

So during a sunny day when the PV system is maxed you're exceeding the inverter capacity of the Powerwall (~16.5kw compared to 15.0kw). The Powerwall inverters can peak at 7kw each for a few moments which may allow enough time for your PV to ramp down/off, but I'd expect if it was configured wrong that you would expect the behavior you saw. Perhaps with some tweaking to align your PV inverters with the Powerwall settings this issue can be resolved with the new firmware.
 
So during a sunny day when the PV system is maxed you're exceeding the inverter capacity of the Powerwall (~16.5kw compared to 15.0kw). The Powerwall inverters can peak at 7kw each for a few moments which may allow enough time for your PV to ramp down/off, but I'd expect if it was configured wrong that you would expect the behavior you saw. Perhaps with some tweaking to align your PV inverters with the Powerwall settings this issue can be resolved with the new firmware.
When we were trying to get things back on, we tried the individual inverters (5.2 Hz, 5.2 Hz and 7.6 Hz) and still had the same problem. Believe me, we tried every possible combination but things kept cycling off between 5 minutes and 30 minutes after getting solar up and running again. The Powerwalls kept putting out 66 Hz even though they were down to 5% or less SoC.
 
Our solar system is 16.575 kW but we our inverters add up to 18 kW. We currently have 3 Powerwalls.

If your peak solar output exceeds the peak input of the Powerwalls, you could program the inverters to a lower output. My Solar Edges have that capacity, in fact it arrived programmed at 50% so I initially thought I had a defective unit.

But if you are only 1.6 kw above peak PW capacity, that would only happen around solar noon on your best days. And then you need to subtract how much your house is actually consuming, it certainly isn't zero.

You might want to verify that your PowerWalls are programmed to to correct make and model solar inverters you use.
 
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When we were trying to get things back on, we tried the individual inverters (5.2 Hz, 5.2 Hz and 7.6 Hz) and still had the same problem. Believe me, we tried every possible combination but things kept cycling off between 5 minutes and 30 minutes after getting solar up and running again. The Powerwalls kept putting out 66 Hz even though they were down to 5% or less SoC.

(I assume you mean 5.2kw/5.2kw/7.6kw)

That's really interesting, wonder what the actual problem is.
 
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I have posted on several other threads about my frustration with the 66 Hz problem and the fact that it essentially made the PW2 useless for battery backup as so many things in the house, including our dogs reacted badly.

This morning, I finally got the courage to do my first test power failure under firmware 1.37.0 and I was very pleased with the results.

I flipped the grid breaker with the SOC on my single PW2 at 44% and my two solar inverters (7 and 4 kW) putting out a total of 4.4 kW. I could see on the app that the solar went down immediately but when I got back to the house, the LED lights were not blinking, no UPSs were beeping, and the dogs were not barking. The frequency was 60.0 Hz. 5 minutes later both inverters were online again, powering the house and charging the PW2 at 60.0 Hz. This was major progress, as in past power failure trials, the PW2 would go immediately to 66 Hz and stay there long enough for me to get back to the house, lose patience, shut down the PW2 and start the generator.

As the solar output continued to increase, it fairly quickly got to the point where the PW2 was being asked to accept more than 5 kW. I was surprised how long it took 5.0 or even 5.1 kW without raising the frequency to more than 60.2 Hz, but I knew that eventually something had to give. Fortunately, my geothermal heat pump came on for a while and used ~ 5kW, but when it turned off, all solar went down as obviously as that point it was putting out more than the PW2 could handle. The SOC was 80%. I wasn’t sure what would happen next, but the 4 kW inverter came up successfully 5 minutes later and was able to power the house and continue charging the PW2. I could see my 7 kW inverter try and come on, but somehow the PW2 managed to keep that off while keeping the 4 kW going. Maybe it was pure luck, as I expected I would have to kill one inverter manually to keep the solar going, or charge the car, or cook something, but to have it self-regulate was almost too good to be true. I never saw any significant frequency variation from 60 Hz when I checked my Kill A Watt meter nor did the lights ever blink or UPSs ever beep during the whole test cycle.

In rural Northern and Central California, everyone here is worried about PG&E doing preemptive multiple day power failures when the fire danger is high, and I am counting on the combo of my solar and PW2 to handle most of the time without power. The fact the PW2 is now useful in those circumstances is very welcome. Now if I could just get the 2nd PW2, I might even be very happy.
 
I have posted on several other threads about my frustration with the 66 Hz problem and the fact that it essentially made the PW2 useless for battery backup as so many things in the house, including our dogs reacted badly.

This morning, I finally got the courage to do my first test power failure under firmware 1.37.0 and I was very pleased with the results.

I flipped the grid breaker with the SOC on my single PW2 at 44% and my two solar inverters (7 and 4 kW) putting out a total of 4.4 kW. I could see on the app that the solar went down immediately but when I got back to the house, the LED lights were not blinking, no UPSs were beeping, and the dogs were not barking. The frequency was 60.0 Hz. 5 minutes later both inverters were online again, powering the house and charging the PW2 at 60.0 Hz. This was major progress, as in past power failure trials, the PW2 would go immediately to 66 Hz and stay there long enough for me to get back to the house, lose patience, shut down the PW2 and start the generator.

As the solar output continued to increase, it fairly quickly got to the point where the PW2 was being asked to accept more than 5 kW. I was surprised how long it took 5.0 or even 5.1 kW without raising the frequency to more than 60.2 Hz, but I knew that eventually something had to give. Fortunately, my geothermal heat pump came on for a while and used ~ 5kW, but when it turned off, all solar went down as obviously as that point it was putting out more than the PW2 could handle. The SOC was 80%. I wasn’t sure what would happen next, but the 4 kW inverter came up successfully 5 minutes later and was able to power the house and continue charging the PW2. I could see my 7 kW inverter try and come on, but somehow the PW2 managed to keep that off while keeping the 4 kW going. Maybe it was pure luck, as I expected I would have to kill one inverter manually to keep the solar going, or charge the car, or cook something, but to have it self-regulate was almost too good to be true. I never saw any significant frequency variation from 60 Hz when I checked my Kill A Watt meter nor did the lights ever blink or UPSs ever beep during the whole test cycle.

In rural Northern and Central California, everyone here is worried about PG&E doing preemptive multiple day power failures when the fire danger is high, and I am counting on the combo of my solar and PW2 to handle most of the time without power. The fact the PW2 is now useful in those circumstances is very welcome. Now if I could just get the 2nd PW2, I might even be very happy.

So I don't know how quickly the kill-a-watt refreshes but it is very possible that your PW was changing the frequency for short (<2 second) intervals, which would reset the UL1741 "high frequency ridethrough" timer for both the inverter that was active and the inverter that was inactive. I saw this behavior during my outage test Sunday on 1.37.1 (Utility outage simulation data dump) - on the graphs on that post you can see tiny parts where the frequency changed for just a brief moment.

What make/model are your inverters? If they support frequency based curtailing you could configure them and the Powerwall to interact with each other correctly and never worry about this in the future.
 
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I don't doubt that the frequency did jump several times as that is how the PW2 interacts with the inverters. However, what jumps there were were short enough and close enough to 60 Hz that the UPSs didn't object and my LED lights never flashed on and off. I only glance at the Kill A Watt occasionally when I am wondering about the frequency and there is no doubt that I might miss a brief frequency excursion from 60 Hz. But as long as the house and dogs don't go crazy like they did with 66 Hz, it works for me.

My inverters are a 10 year old SB 7000US 232 and a newer SB 4000TL-US 512. The manuals for both suggest that they should follow the FSPC protocol, but other input on this forum has suggested that that is only when configured for an off grid installation and that their full use of FSPC might violate my something 21 contract with PG&E. More input on that subject is always appreciated!