Recent Powerewall Experience During Scheduled Grid Outage

[scotsmanswan]

Wanted to provide some of my observations during a recent scheduled grid outage to replace some old power poles.

I have a 8.43kW array connected to Sunny Boy 6.0 (6kW max output) and a single Powerwall 2 / Gateway 1 (FW 22.1.1 and iOS app v4.6.1) in a partial home backup setup. Given this my system is certainly maxing out inverter and what PW is capable of managing and I had never tested the grid outage capability in extreme situations so was interested to see what would happen with this scheduled outage during during the day on what would be a good solar production day.

Power was cut about 9.30am so battery had started to charge and was @ ~70%. Battery continued to charge to ~80% during outage which seemed to coincide with ~3.4kW being sent to the battery (I think this is max allowed in "normal" operation). For next 4 hours house was using ~0.5kWh and inverter would cycle on for brief periods charging at rates in excess of 5kW (see first 2 pictures) and maintained a 80% charge. At about 2.45pm (battery still charged to about 80%) the inverter turned on permanently and seemed to charge Powerwall at rate of 5.2kW (see 3rd picture showing battery behaviour during the day). Power was restored about 3.30pm and about 5 min later normal operation reasumed.

During the day I was expecting the cycling of the solar as excess production was going to be > 5kW but the Powerwall did seem to accept the input for a few minutes and did not immediately shut down and certainly later in the day (@ ~2.45pm) it did allow 5.2kW continuously so I wonder if it was simply optimizing what is needed to do to balance need v pushing throughput to the extreme but at the same time making sure battery @ 100% at end of day... I also noticed from my Ting monitor (a great fire safety monitoring device I got from a partnership they have with my insurer, StateFarm) that the voltage was being allowed to vary significantly (see 4th picture); I suspect this is how Gateway / Powerwall manges the power throughput without exceeding the 30 amp maximum.

 

[EVRider-FL]

It’s interesting that you posted this, because it sort of answers a question I had about a brief grid outage I experienced a short while ago. When it happened, the Tesla app seemed to be showing no solar production during the outage (sunny outside at the time). I was wondering if that was normal, but I can see from your photos that you had solar production during your outage.

So now the question is whether I really lost solar production, or that’s just what the app was showing. The grid outage was only 5 minutes, and the only reason I knew about it is because the UPS connected to my computer switched to battery mode (I didn’t get a notification from the Tesla app). From what I’ve seen in this forum, a UPS doesn’t handle the slight change in AC frequency that happens during an outage, so I suppose I should stop using it.

 

[Steve2498]

…When it happened, the Tesla app seemed to be showing no solar production during the outage (sunny outside at the time). I was wondering if that was normal, but I can see from your photos that you had solar production during your outage.

Have you tested being off grid when the battery is less than 90% and the sun is out to verify your solar will produce, as they should? If not you need to to verify correct operation.

When my PWs were installed, when off-grid, the system was shutting down solar production regardless of the battery’s SOC. It took them over a month to get it fixed, but it does now work properly.

To the original poster, I find it odd that it appears you were charging your batteries at > 5kW from 10:50 to 11:24, yet your battery’s SOC stayed at 79%! I would have expected it to have gone up to the mid to high 80’s In that time and at that charging level.

 

[scotsmanswan]

To the original poster, I find it odd that it appears you were charging your batteries at > 5kW from 10:50 to 11:24, yet your battery’s SOC stayed at 79%! I would have expected it to have gone up to the mid to high 80’s In that time and at that charging level.

The screen shots were just take at a time that the battery was charging (but just for a few minutes at that rate). I think it did this a few times between 10:50 and 11:24 but not continuously.

 

[EVRider-FL]

The reason I wasn’t seeing solar production during the grid outage yesterday was because my Powerwalls were at 100%, which I learned is expected behavior. Apparently the gateway shuts down solar production in that case because the electricity has nowhere to go.