Frequency Response During Power Outage

[aesculus]

Just a quick observation:

Today I had an unscheduled power outage just before peak at 3PM. Powerwalls (2) were at 100% and solar was being returned to the grid. There was a quick pause in power (a few none UPS devices restarted and one needed manual restart). Frequency jumped to 60.3 which was enough to shut down my two Fronius and one Delta inverters.

I was watching the PW charge state as well as the frequency for about an hour with a Kill a Watt. Occasionally the frequency would dip to 60.2 and that was enough to restart the inverters. I was only drawing 600 watts for the house at the time. During another event the house was drawing 1.5 kW and the frequency was 59.99 Hz. The PWs were still at 98% but probably at the low end. So that game of going between 60.2 and 69.3 seemed to go on for awhile.

But at around 5PM my solar was starting to fade with shading and cloud cover and the max was about the house consumption so the frequency one again returned to 59.99 Hz.

Seems to me that at 98%, with only producing a few kW they could have kept the solar alive but I am probably splitting hairs. Maybe because my systems seem to be all or nothing at 60.3 Hz.

 

[ptdusn]

That is true, the Solar would not come back on until the PWs reached around 90% charge.

 

[aesculus]

As I pointed out above, my solar systems cycled on/off at the high and low of 98% PW SOC. They never dropped below or went above 98% during the 3+ hours of the power outage.

 

[morph3ous]

That is how mine works as well in an outage situation. Last time I tested an off-grid (throw the disconnect) situation this is what I saw.

Powerwalls would charge up to 100%, then the frequency went up and solar production stopped.

Then once they dropped down to 98%, solar started producing again. The frequency went slightly up and down and solar production was curtailed to roughly match consumption. The Powerwalls stayed at 98% the whole time like yours.

I liked this behavior and thought it was pretty slick.

 

[jboy210]

Mine worked the same way as yours during our outage yesterday. We saw the batteries dip to 98% or so and then return to 100%. I could not correlate the dip to load or solar production. Both stayed pretty constant.

 

[Ahh9oolu]

I don't have frequency for this event, but I do have graphs of a power outage and the corresponding discharge/charge cycle. The first image is for the full day. The blue line at the top is the Powerwall charge % (right axis), the orange line is the solar output, and the yellow line is Powerwall energy (negative is charging, positive is discharging.

The second image is a closeup of some of the spikes, but unfortunately has different colors. The green line is Powerwall draw (negative for charging), and the cyan line is solar generation. Based on our usage at the time, the batteries charged every 15ish minutes, but only for a minute or so each time.

This is with 2x Powerwalls, and 6.72 kW solar panels with Enphase microinverters, and a house that was not drawing much at the time.

 

[BGbreeder]

I would call installer. Now. Something is not right in the gateway, or connection to the Powerwalls. What I find interesting is that it looks almost as if your solar connection is loose and it makes contact, heats up, breaks open, cools, and then makes contact again.

Has your system always done this?

All the best,

BG

 

[power.saver]

I would call installer. Now. Something is not right in the gateway, or connection to the Powerwalls. What I find interesting is that it looks almost as if your solar connection is loose and it makes contact, heats up, breaks open, cools, and then makes contact again.

Has your system always done this?

All the best,

BG

No, I'd say that those graphs look right. With so much solar production and so little house draw, the charge time is very short. The PW was at 98% so this will cycle the solar on and off. With non-Tesla inverters, they may not be able to ramp down production, and it goes on and off instead. My system behaves this way when the PW is nearly full.

 

[BGbreeder]

My bad; I missed that it was an outage. No worries.

All the best,

BG