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How to manage PW when grid is out and solar power generation is intermittent

Most people have PWs configured this way because it's a requirement of the tax credit. However, Storm Watch is intended to be the exception to this rule, allowing grid charging for adverse events.
In my case StormWatch seems to keep my PW reserve at 100% (instead of my normal 20%) so PW are not used when grid is on (like at night when PW's power the house)
So during a power outage - should I physically turn off PWs at say 20% to preserve power for restart when solar is available? - Is it best to just use switch on sides of PWs? And then stagger startup load using breakers in my electrical panel?
 

miimura

Well-Known Member
Aug 21, 2013
7,182
7,133
Los Altos, CA
To turn off PW to preserve power for restart when solar is available - Is it best to just use switch on sides of PWs? And then stagger startup load using breakers in my electrical panel?
If you want to pre-emptively shut down the Powerwalls during an outage, the rocker switches on the side would do the job. When you go to restart it, turn off all the load breakers, then turn the Powerwalls back on. Look at the power flow on the app (or Gateway local web interface) to make sure the system is up and the solar is active and charging. Then start turning on load breakers.
 
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If you want to pre-emptively shut down the Powerwalls during an outage, the rocker switches on the side would do the job. When you go to restart it, turn off all the load breakers, then turn the Powerwalls back on. Look at the power flow on the app (or Gateway local web interface) to make sure the system is up and the solar is active and charging. Then start turning on load breakers.
That would only work when you’re also jumping the gateway too, right? Otherwise the gateway doesn’t have any power. Our first outage was pre-PTO for the batteries so they were both shut off. I didn’t think to turn off the breakers in the main panel, but just flipping the PW rocker switches did nothing for me.
 

miimura

Well-Known Member
Aug 21, 2013
7,182
7,133
Los Altos, CA
That would only work when you’re also jumping the gateway too, right? Otherwise the gateway doesn’t have any power. Our first outage was pre-PTO for the batteries so they were both shut off. I didn’t think to turn off the breakers in the main panel, but just flipping the PW rocker switches did nothing for me.
I said the rocker switches should turn OFF the system. I am not claiming that turning the rocker switches back ON will be sufficient to cold start the system. There is a good chance that the Jump terminals will be needed to start the system when the grid is down.
The main reason for turning off load breakers is to give the system enough time to get the solar started and generating before the system shuts down for low SOC again.
 
I said the rocker switches should turn OFF the system. I am not claiming that turning the rocker switches back ON will be sufficient to cold start the system. There is a good chance that the Jump terminals will be needed to start the system when the grid is down.
The main reason for turning off load breakers is to give the system enough time to get the solar started and generating before the system shuts down for low SOC again.
Thank you for this info. I am working on a procedure to set up for any extended grid outage. I am hoping that in the event of an extended grid outage I can preserve enough power in PWs to power inverters when solar is available again (eg, daytime and panels not covered in snow). I can then turn on PWs so inverters can start generating power from solar to power up PWs and I can slowly turn on breakers.
 
Why wouldn’t the gateway get the power it needs from the powerwalls when they’re turned back on?
All I know is that when the grid was down (at night) and my (pre-PTO) powerwalls had the rocker switches set to “off”, simply turning them to “on” did nothing to restore power. Maybe I didn’t wait long enough? Not really in the mood to shut down power to the house right now, but I’ll take someone’s word if they want to give it a shot.

My guess would be that since the GW is the brains of the operation, it needs power to signal the PW to start providing juice. So you have a catch-22 where the gateway has the brains but no juice, and the PWs have the juice but no brains?

I said the rocker switches should turn OFF the system. I am not claiming that turning the rocker switches back ON will be sufficient to cold start the system. There is a good chance that the Jump terminals will be needed to start the system when the grid is down.
Ok. Yea I followed the part about shutting them down, just wasn’t sure about the restart since you didn’t mention jumping the GW in that post.
 
Why wouldn’t the gateway get the power it needs from the powerwalls when they’re turned back on?
For safety I believe, it's designed this way. If the system goes down, while the grid is down the only way you are getting it to cold start is with a DC source.

Also, remember a cold lithium battery may not take nearly the same PV charge as one that has been on a while and is properly warmed. Do not expect it to take more than 0.8-1 kW each at first, especially when cold soaked. In extreme temperatures, for safety and battery health they may not accept any charge at first.

The Powerwall do have internal resistance heaters, but it is a delicate balance between cell temperature, charge/discharge rate and PV generation especially with an older PV system that doesn't smoothly curtail PV generation in response to the frequency shift signal.

In general, it is better for battery health to stay connected and with the internal coolant pumping properly keeping the cells in working range.
 
So having gone through this with a recent outage in Hawaii, and my solar production/inverter not working the powerwalls will actually go down to 5% not 10% that's listed on the website. At the moment it hits 5%, it'll shut down electricity to the house. Every hour from 8am - 4pm, it'll turn the inverter and house load on for 6 minutes to test if the solar production is working.

It's very smart, the only problem for me was my Inverter for whatever reason not turning on.

I reconnected my solaredge inverter to the internet, and I tested the "off grid" setting, and the solar works. The only thing different is the tesla app in "off grid" mode shows an orange x, whereas when the electric grid was truly out, the x was red.
 

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