Powerwall 2 during outage

[russmd]

I recently had 3 Powerwall 2's installed in a whole house configuration, added onto my existing solar. I've been tinkering with settings - Backup vs Self-powered - and have a couple of questions. Lately, I've been leaving it in self-powered at around 60% which allows the solar to run my house and charge the walls most of the way during the day while allowing the walls to run the house most of the night.

1. I noticed that the "Backup" option has a percentage reserve power setting available just like the Self-powered mode. I believe self-powered set at 100% is essentially the same as backup 100%. What's the difference then considering Backup has a percentage slider available also?

2. Scenario - grid power is shut off by the utility, as they are doing pre-emptively in our area in California. If while solar is running the house the batteries become fully charged, what then happens to the excess solar power generated - the power that usually goes back to the grid. The grid was "shut down" by the utility. Does that power back feed into the grid causing any kind of danger? Does it have someplace to go? It has to go somewhere. Or does the solar deactivate some of its production capability? Would like to know for safety.

Thanks,
Russ

 

[jrweiss98020]

If the grid is shut down, the Tesla Gateway disconnects your house from the grid. Solar panels will cycle on & off when the Powerwalls are charged to 100% and there is excess production.

The Gateway samples the grid power. When it detects power has been restored, it will reconnect the house to the grid after 5 minutes.

 

[russmd]

If the grid is shut down, the Tesla Gateway disconnects your house from the grid. Solar panels will cycle on & off when the Powerwalls are charged to 100% and there is excess production.

The Gateway samples the grid power. When it detects power has been restored, it will reconnect the house to the grid after 5 minutes.

Thanks - so the solar panels will regulate production in that instance, good to know. Any answers to question #1?
Russ

 

[AEdennis]

Not sure if this answers it.

But backup % is what you're reserving to STOP consuming battery power during grid connected days.

So, if you tell it to reserve 40% of the battery for backup, if you're consuming the battery and your battery SOC hits 40%, it will draw from the grid or panels and leave the battery alone.

 

[getakey]

The reserve % should not really apply to backup only. Its just there on the same screen

 

[jboy210]

Thanks - so the solar panels will regulate production in that instance, good to know. Any answers to question #1?
Russ

Small correction. Tesla Energy gateway (TEG) controls this behavior and acts as a switch routing electrical power on various circuits and shutting off the solar inverters as the batteries start to reach full. The TEG settings are what you are controlling when moving the sliders in the app.

Without something like the TEG to control power flow and Powerwalls to store power, in an outage, solar will just get shut off so no power is sent out to the grid to prevent possibly shocking some unsuspecting power worker. And in the meanwhile, you would be starting at all those panels on your roof providing no power to your house from all this bright California Fall sunshine. And get more and more upset as the outage goes on and on.

 

[russmd]

The reserve % should not really apply to backup only. Its just there on the same screen

Got it. In backup, the slider is there but locked to 100%. Thanks.

 

[russmd]

Small correction. Tesla Energy gateway (TEG) controls this behavior and acts as a switch routing electrical power on various circuits and shutting off the solar inverters as the batteries start to reach full. The TEG settings are what you are controlling when moving the sliders in the app.

Without something like the TEG to control power flow and Powerwalls to store power, in an outage, solar will just get shut off so no power is sent out to the grid to prevent possibly shocking some unsuspecting power worker. And in the meanwhile, you would be starting at all those panels on your roof providing no power to your house from all this bright California Fall sunshine. And get more and more upset as the outage goes on and on.

makes sense. Thanks.