No grid, Powerwalls drained, what happens to solar?

[Troglodytes]

Anyone know from experience what happens in a prolonged outage when the grid is out and powerwall 2s are drained of charge? [Defined as 0% available per the app.]

Will solar production/inverters be able to start back up using residual sub-zero-percent charge in the idled powerwalls?

Can inverters bootstrap themselves with sufficient solar production and charge the powerwalls in a prolonged grid outage? Safely with a Tesla gateway?

Or, in a prolonged outage does some minimum of the remaining power need to be protected by the user by turning off all loads except the inverters?

Worst case.. use an DC-AC car inverter with a running car to get the solar inverter to do some solar production?

 

[sorka]

I'm guessing it isn't going to work. i.e one should probably shut down the powerwalls when the grid is off before reaching zero so you can turn them back on when there's sunlight outside.

Ideally, you'd have an inverter that can be powered on by DC solar production with a setting to override and turn on when there's no detectable sync source from AC when you know there's a GW between the main panel and meter.

Hybrid inverters that are meant to be truly off grid can already do this so that when you storage is depleted, it will come back on when solar production restarts.

 

[woferry]

My recent experience is documented here. Basically, I don't think the system will let you drain it to 0% but will stop at 5% in the app (10% Gateway SoE). And I was able to use that leftover energy to get my system running again once there was enough sun for the inverters to start producing, just by hitting the reset button inside the Gateway (and waiting the ~1 minute for the GW to reboot, then the 5 minutes for the solar inverter(s) to start producing again). Though I think it would be wise to first turn off any other home loads, to ensure you don't overload the PW(s) or draw them down too quickly during this period. Presumably there's a SoE level at which the PW won't even try anymore, I wasn't interested in discovering that level.

 

[BrettS]

In the powerwall documentation it says that if the powerwall shuts down due to lack of power then it will attempt to periodically restart the system during daylight hours to see if there is solar power available. If there is, then it will stay on and continue running the house. If there is not then it will try again later. At some point, however, it will eventually run out of power and/or give up and need to be manually restarted. You can also manually restart it when solar power is available by power cycling the powerwall (It’s only necessary to power cycle one powerwall if you have multiple).

 

[jboy210]

FWIW, you can "jump-start" the Powerwall Gateway with a battery to get things back online. There is a 12V DC port for just this purpose.

 

[nyprepper]

Anyone know from experience what happens in a prolonged outage when the grid is out and powerwall 2s are drained of charge? [Defined as 0% available per the app.]

Will solar production/inverters be able to start back up using residual sub-zero-percent charge in the idled powerwalls?

Can inverters bootstrap themselves with sufficient solar production and charge the powerwalls in a prolonged grid outage? Safely with a Tesla gateway?

Or, in a prolonged outage does some minimum of the remaining power need to be protected by the user by turning off all loads except the inverters?

Worst case.. use an DC-AC car inverter with a running car to get the solar inverter to do some solar production?

One thing to keep in mind...... my Tesla crew installed a breaker box outside my house house next to the meter. It contains a circuit for the PW's and a circuit for the PV. They were very adamant that if I needed to recycle the PW's I should do so via the switches on the PW's themselves...NOT via the breaker. This is so that the PW's can follow the proper shut down sequence and start up sequence.... Kind of like using the shutdown/restart option on a Windows desktop rather than just unplugging it.

 

[charlesj]

.... Kind of like using the shutdown/restart option on a Windows desktop rather than just unplugging it.

Unless the computer is frozen and cannot shut it down.

 

[Doom Man]

Here are some answers from Tesla:
Best Practices During Power Outages | Tesla Support

 

[BrettS]

Here are some answers from Tesla:
Best Practices During Power Outages | Tesla Support

Thanks for that link. I looked for that info earlier, but I couldn’t find it again. Here is the relevant part in regard to the original question:

If Powerwall has less than 10% energy remaining, it will enter a standby state. Powerwall will automatically attempt to recharge from solar for 6 minutes every hour between 8 am and 4 pm local time. If enough solar is available to charge Powerwall, it will remain on. Otherwise, it will wait for the next hour.

 

[Troglodytes]

Very interesting... thanks for the link and the excerpt!