I am located in Emerald Isle NC, about 60 miles from where Hurricane Florence came ashore last week. We were in the Northeast quadrant and took quite a pounding. My house, 1/4 mile back from the beach, emerged essentially unscathed, so I count myself very lucky looking at my neighbors. Our power recovery was good and we were without grid power for only about 90 hours. When the grid dropped, we turned off nonessential loads, and the Powerwall took us over 24 hours, and I turned it off when it reached about 10% knowing I wanted enough power to restart eventually. However, the clouds were VERY thick (30 inches of rain) and did not see the sun or even thin clouds for that whole time, until today (September 17). I turned off my system (solar and Powerwall), and used my propane generator for the rest of the outage. However, when I turned things back on, the Powerwall did not start. The solar didn’t start because it saw no grid or no Powerwall. I called my installer, who didn’t know, and suggested I call Tesla. They actually answered the phone quickly and tried to be helpful but essentially said what I suspected that the Powerwall didn’t have enough power to start. Fortunately, about an hour after that, the grid came back, solar booted up (SolarEdge inverter), then the Powerwall got power, started, and all is happy...except me, since I don’t quite understand this behavior. I thought I’d saved enough power, and wonder why it dropped so the Powerwall wouldn’t start. I know that in daily normal operation some of the stored power in the backup reserve is used (drops below the reserve %), but when the Powerwall is off I would think this is minimal. It makes me wonder if something is not quite configured correctly. My configuration is a bit unusual in that I’m self consumption for all my solar, since my utility doesn’t do net metering. I take from the grid but never give back. Thoughts? -Joel
I recently came across an old post that claimed you were supposed to be able to toggle the power on the Powerwall to get it to try to restart after running out of charge. You are supposed to be able to do that when the power is out but solar is available to restart the system. I don't know if the person tried it out, though.
Thx for the response! Would love to get to the bottom of this. A question, do you recall what was meant by “toggle the power?” Was there some undocumented “magic incantation” or process when you flipped the switch that was supposed to restart? With only one switch insofar as I know, it’s hard to do the sort of multi-finger clicks we do to restart many of our gadgets. -Joel
I don't recall all the details, but I recall people saying that when Powerwall shuts down due to low SOC, it won't restart until it thinks the grid is up. You shut it down manually, so there should be a way to get it to cold start, but I don't know the correct procedure, if there is one. This is the main reason that I looked into doing runtime extension. I don't want my Powerwalls to ever shut down during a natural disaster. Powerwall 2.0 Backup Runtime Extender
I noticed the powerwall loses about 1% a day when not being used, but online. I shut mine off at 8% (flipped the switch and turned off the breaker to the powerwall) and when I turned it back on a few weeks later when I got PTO it was still at 8% if I remember right.
That was what I was expecting. Still not sure why mine didn’t start back. Thanks for the data point... -Joel
Have you tried just turning off the breaker but leaving the switch on? I seem to recall a discussion about PW won't power up if it doesn't see the grid power. I know it will continue to lose 1%/day if you leave the switch on, but it may be the only way to start up solar if there is no grid power.
Interesting thought. That might be the way to go for an outage like a hurricane where we know we have 3-4 days with no sun. However, not sure I want another hurricane to test this out! ;-) -Joel
From the Tesla Powerwall FAQ page: To resume Powerwall operation, turn off all lights and appliances in your home, then toggle the on/off switch located on the side of Powerwall. If, after an extended utility outage, Powerwall is depleted, then wait for the next sunny day before toggling the on/off switch. I believe in your situation, you had already turned the switch off. So it may be necessary to turn it back on, then toggle it off-on again. There should be minimal house loads when you do this, ideally just your inverters, so the PW can get started without having to push out any power. If your house loads are connected, it might be too much draw from the depleted PW state. If there is enough energy left in the PW, it should be able to generate the voltage and frequency to get the inverters on-line, and then start charging. Once you have enough charge in the PW, reconnect the house loads.