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PowerWall Cold Start without Grid Power

Discussion in 'Tesla Energy' started by Cottonwood, Apr 7, 2018.

  1. MorrisonHiker

    MorrisonHiker S 100D 2020.8.2

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    I'll try turning all the breakers off except the Powerwalls and see if I can get them charged up and keep the solar system running before I turn anything else back on. Fortunately the gateway also had a cellular connection so I can monitor what's going on.

    Someone from Tesla is coming by before noon. Hopefully I can get things working before the pipes freeze in the radiators. That happened once before and is one of the reasons we got solar and Powerwalls installed!
     
  2. mongo

    mongo Well-Known Member

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    Do you happen to have a naturally vented gas water heater you can use as a heat source?
     
  3. MorrisonHiker

    MorrisonHiker S 100D 2020.8.2

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    The water heater/boiler is naturally vented but relies on electrically operated control valves. I didn't see a way to turn them on manually. We do have a natural gas fireplace on the main floor which keeps that floor and the upper floor from getting too cold. Now I'm thinking we might need to put one in the walkout basement as well.
     
  4. mongo

    mongo Well-Known Member

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    Gotcha, combined system.
    My first house was in an area with rapid housing expansion that overloaded the grid, found all the ways to make heat without electricity.
    Depending on load, can you run the boiler on a 12V battery and inverter?
     
  5. MorrisonHiker

    MorrisonHiker S 100D 2020.8.2

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    #45 MorrisonHiker, Mar 15, 2019
    Last edited: Mar 15, 2019
    That might be possible but I'd have to get an HVAC guy out to show me.
     
  6. MorrisonHiker

    MorrisonHiker S 100D 2020.8.2

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    I have that a go but still no dice. The sun came up and I turned off all breakers to the house. I turned one of the Powerwalls off for a second to reset things and then turned on one inverter. It instantly synchronized and ran for a couple minutes and produced 30W at about 1800W before it reported External Events and then went back to trying to synchronize. I tried the smaller arrays too but got similar results. I'm going to wait a few minutes before checking again but it's 8 degrees F with the windchill today. Totally sunny though so if we can get it working, we should be able to charge the Powerwalls in a few hours.
     
  7. mongo

    mongo Well-Known Member

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    Gotcha, it is not the simplest (or even necessarily a good idea) to repower an appliance.
     
  8. abasile

    abasile Conscientious investor

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    One way or another, I hope that you will be able to power your house soon! I can understand the frustration of having a technological solution for your exact situation, and having it fail just when you need it. Hopefully, Tesla can work out the bugs soon. Elon did say last night, among other things, that 2019 will be the year of the Powerwall. We still have a Tesla visit scheduled for later this month to investigate our Powerwalls' failure to charge from solar during grid outages.
     
  9. MorrisonHiker

    MorrisonHiker S 100D 2020.8.2

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    The sad thing is that is Storm Watch had activated, we would've had 100 percent and made it until this morning or this afternoon. Since we had plenty of sun yesterday and today, I think they would've been able to charge if they were above the magical 5% {at least according to what others have said}.

    We did tweet Elon about Storm Watch and he said they would change it soon to work for blizzards and other severe weather. Hard to believe they had it set to activate for high winds but not for blizzards which are high winds and snow combined!

    If I don't see it activate next time, I'm calling in and will manually bump the reserve up all the way. I thought the 50% would get us through since the longest outage we've had in 23 years was 8 hours. This one is almost 48 hours so far.

    The neighbor's generator just went silent. I wonder if it ran out of gas or finally died after two days of nonstop usage...or maybe the grid is back up!
     
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  10. MorrisonHiker

    MorrisonHiker S 100D 2020.8.2

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    The grid is back up and I'm back in business. Tesla is still sending someone out today. Hopefully they can figure out what went wrong and prevent it from happening again. Thanks for your messages and suggestions. I'll reply back with an update once they figure out what the problem was.

    Another interesting observation is that it appears to be actually charging the batteries with a little help from the grid.
    Screenshot_20190315-095900_Tesla.jpg Screenshot_20190315-100017_Tesla.jpg
     
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  11. MorrisonHiker

    MorrisonHiker S 100D 2020.8.2

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    A Tesla FST (field service technician) came out today and was able to recreate the problem. To fix it, they are first going to remotely install firmware updates on Sunday night on each inverter. I guess it takes up to 3 hours per inverter but they don't have to sit there and watch it the entire time. Then on Monday morning the FST will come back out to adjust the allowed frequency range. I know someone pointed it out (either here or another thread) and mentioned to check the frequency. I mentioned this in my first call to tech support the other day but the rep just blew it off as if I didn't know what I was talking about.

    As many of you probably know, the Powerwalls intentionally raise the frequency to signal to the inverter that they are full and to stop producing if the grid is down. We did see a high frequency of 63 Hz on Wednesday morning right when the power went out during the blizzard. Anyhow, the inverters are currently set to shut down if the frequency goes above 60.5 Hz. He is going to increase the frequency range and confirm the solar will still be able to function.

    I don't remember seeing a Frequency Error when it repeatedly reported External Event yesterday but I forgot to look through the logs on the inverters. Hopefully that's the issue and things will be fixed on Monday.
     
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  12. miimura

    miimura Well-Known Member

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    Maybe I'm not reading it right, but this seems like a backwards approach. Why are they applying updates to the solar inverters when the Powerwalls are erroneously changing the frequency? IMHO, the Powerwalls should hold the frequency at 60.0Hz until they either approach some high percentage of charging power (like 80%) or some high state of charge (like 90%).
     
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  13. MorrisonHiker

    MorrisonHiker S 100D 2020.8.2

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    From what I understand, the Powerwalls might've had an issue since they were cold and at a low state of charge, down to add low as 2% at one time. I think this is why others have warned to not go below 6%, but I'm not certain.

    He did call both Tesla and Delta advanced tech support and for now, the solution is to adjust the inverters. It sounds like they will escalate it to the Powerwall developers as well, so maybe it will be addressed in a future Powerwall firmware update too. He said it happens with other brands of inverters too, so it does seem like they could address it on the Powerwall side.

    I'll try to discuss it with him again on Monday.
     
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  14. mongo

    mongo Well-Known Member

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    Huh, sounds like the PW couldn't sink current, so it set the frequency to 63 Hz to indicate such (couldn't have been that high from the inverters). Seems like instead it could just not charge and let the solar either trip out on overvoltage or fold back it's output, but that would require trusting the inverter's response.
     
  15. miimura

    miimura Well-Known Member

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    If the Powerwalls had been operating properly (holding the frequency steady at 60.0Hz) at the beginning of the outage, they would not have fallen to low SOC to begin with. Also, as soon as the grid came back, they quickly started charging with more than 5kW of power.

    I have no problem with the Powerwalls increasing the frequency when they get full or the total solar is overwhelming the charging ability of the Powerwall(s). However, it looks like @MorrisonHiker did all the right things like shutting off some of his solar inverters to limit the power, but the Powerwalls were not working properly. I maintain that there is a significant bug in the firmwares newer than 1.29.
     
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  16. mongo

    mongo Well-Known Member

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    Good point on the behavior upon power restoration, could part of that be their internal heaters though?
     
  17. MorrisonHiker

    MorrisonHiker S 100D 2020.8.2

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    He did mention the internal heaters running. It wasn't that cold in the garage. Maybe 34 F, but I guess that would be cool for the batteries. I did hear the fans running on at least one of them.
     
  18. miimura

    miimura Well-Known Member

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    Also, at one point the solar was running for 30 minutes and that should have been enough time for the heaters to get the Powerwalls up to operating temperature so that they could maintain stable frequency and solar operation.

    I re-read the story from the beginning and now realize that the Powerwalls shut down at low SOC before the snow was cleared from the panels, hence the inclusion in this thread about cold starting. So, this experience could be completely related to cold starting and the Powerwalls never reaching a stable operating point. However, I doubt it. I still think this is due to the same bug in the frequency control algorithm that many people are seeing.
     
  19. MorrisonHiker

    MorrisonHiker S 100D 2020.8.2

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    The Tesla FST came back out yesterday after the firmware was updated on all three inverters. He then modified the settings so that the inverters won't shut off under such a tight frequency range. Previously, they were set to shut off if the Powerwalls had a frequency of 60.5 Hz. I don't remember the exact frequency he updated them to but I believe it is something more like 62 Hz. I'll ask tomorrow what the new setting is.

    I did ask about just updating the Powerwalls instead of the inverter settings. He mentioned they would have to address that in a future Powerwall firmware update.

    Everything worked fine yesterday but the panels were only producing at about 50% since it was late in the afternoon and it was pretty cloudy out. He's going to stop by again tomorrow close to noon and do another test to confirm the system will still start up if the panels are producing at 100%. He said that if there are problems, there are new settings were he can shut things down in stages instead of all-or-nothing.

    If it passes his test, one of these weekends I'm going to take the Powerwalls back down to 5% and simulate a grid outage again and confirm things work correctly when the Powerwalls have such a low SoC.
     
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  20. miimura

    miimura Well-Known Member

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    I think the first step should be to verify that the system works properly when the grid is down and the sun is shining. Then add the additional requirement of cold start, like if they shut down due to low SOC overnight.
     

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