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Export to grid occasionally lower than expected

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I’m signed up for a battery power export program, and my gateway is set to export 5KWs for 2 hours each evening. This has been working flawlessly since originally provisioned back in April. However, twice this week, the export has been just over half the normal amount during the configured period. There have been no changes to the configuration, at least by me, since it was commissioned.

Does anyone have any idea why this would suddenly stop exporting less than the configured amount power? I’d like to think it would have something to do with the grid, but I don’t see how. Typically the battery is discharged to 27% at the end of the 2 hour export period; when this happens, the battery is still showing a 49% charge, which is consistent with the amount of export it’s been doing.

It appears as though logs of what’s going on with the gateway are not available to anyone but Tesla. I did a gateway and Powerwall reset just for the heck of it, but I doubt it will have any effect on the situation.
 
FWIW I am 22.18.3 with 2 PWs and mine exported today at 10 Kw for the PWs plus 2 kW for solar at the time. It waited until the solar dropped pretty extensively until it exported at that rate and then for the last two hours of peak it poked around at a few 100 watts export plus keeping the house supplied.
 
Tesla Energy told me to reset the Powerwall to fix this problem. That entails turning the switch off, and then the breaker to the Powerwall, and waiting at least 30 seconds. The green light continues to shine, even with the breaker off.

You then turn the breaker on, Powerwall back on, and wait, it seemed like 10-15 minutes, for the battery to decide to reengage with the solar system. Tesla suggested it could take 24 hours to fully reset itself.

The Powerwall has just started discharging into the grid, but so far, it appears to have worked.

It’s odd to think that the same technique used for decades with Windows PCs seems to be appropriate for our batteries, but it’s all just software.
 
I think I finally cracked this problem!

When I started to discharge to the grid at the rate set in the Powerwall of 5000w, the Powerwall initially worked just fine. After about 20 minutes, it gradually starts to reduce the power it outputs, until it gets down to around 3000w.

I had assumed something was wrong with the battery, perhaps overheating, or something wrong with the Powerwall software that changed the way the battery discharges. I had the installer out, and he could find nothing wrong; which drove me nuts!

Finally, I decided to monitor the Powerwall more closely when it was actively exporting energy, and when it started to cut back.

Here’s what I found: the battery happily ramps up to 5000w within 90 seconds or so, then within 5 minutes it drops to a lower number, like 4000, and then once again slowly increases back towards 5000w. Subsequent drops to 3500w, and then 3000w occurs, at which point it eventually stops trying to increase and settles in at a lower rate.

HOWEVER, just before each reduction, a strange thing happens; the frequency of the grid rises from a solid 60.0hz to 60.1hz!

Since the Powerwall doesn’t control this frequency, the issue lies with the grid. That small raise in the frequency is apparently known as the “volt-watt” function, and it‘s a way for the utility to tell the Powerwall, “please reduce your output”. This was referred to in the export agreement that I signed, but I had no idea what it was or why.

I sure wish Tesla could have diagnosed this problem by looking at the logs of the events. They apparently, at least at level 1 customer support, can only see the same things we can on the app, not the underlying status of the system.