Improved off grid behavior

[onautopilot]

I have 12k of solar and 3 PW 2’s. I have two Tesla inverters.
I have been running in off grid mode since I’m waiting for PTO. Prior to now I noticed that it would either entirely turn on or turn off the solar array when the batteries are near 100%. Now though it seems to be adjusting the array to cover the electrical draw of the house. For instance at mid day today I’d normally be producing 8k. It is however showing 500 watts… the exact amount my house is using.
Is this a software upgrade? Has anyone else noticed this? It’s a pretty big improvement in my opinion. Rather than turning the batteries on and off.

 

[gpez]

I have 12k of solar and 3 PW 2’s. I have two Tesla inverters.
I have been running in off grid mode since I’m waiting for PTO. Prior to now I noticed that it would either entirely turn on or turn off the solar array when the batteries are near 100%. Now though it seems to be adjusting the array to cover the electrical draw of the house. For instance at mid day today I’d normally be producing 8k. It is however showing 500 watts… the exact amount my house is using.
Is this a software upgrade? Has anyone else noticed this? It’s a pretty big improvement in my opinion. Rather than turning the batteries on and off.

It's possible Tesla updated your configuration to enable this. Enphase has been advertising that they support curtailment with their full battery + PV systems. Even mixed systems can support this: I have Enphase inverters but the Tesla Powerwall and have configured it to do the same.

While it's cool don't get super excited - having curtailment is not really a huge advantage over turning the batteries on and off. At the end of the day almost the exact same amount of PV is "wasted".

Let's say your system previously oscillated between 100% and 96% from solar full off to solar full on. That means that, worst case, the Powerwalls start at sunset at 96%. For a PW 2s that's an absolute maximum of 13.5kWh * 0.04 = 0.54 kWh. That's assuming you have a fresh Powerwall (my 2.5 year old PW2 is reporting 12.0kWh capacity) and it would be rare for that timing to work out absolutely perfectly wrong so you're really only talking about an extra 0.20 kWh/Powerwall available overnight or 0.60 kWh for your 3x PW2 system. In a grid outage situation I'll take every spare Wh I can get but it's really not a big amount.

 

[onautopilot]

Thanks for the thoughtful reply. Yeah alright you curtailed my excitement… with math. I had emphase for my prior house. I kinda saw the panel level control as one of the big advantages of using their platform. The on/off switching of the powerwalls is pretty much seamless though. So yeah probably not a significant advantage.
Does the gateway communicate with the inverters? I thought it would just generically run up the frequency until any inverter would shut down. But that doesn’t make sense with the new behavior.

 

[gpez]

Thanks for the thoughtful reply. Yeah alright you curtailed my excitement… with math.

I got it!

Does the gateway communicate with the inverters? I thought it would just generically run up the frequency until any inverter would shut down. But that doesn’t make sense with the new behavior.

For my Enphase + Powerwall system no direct communication, they talk to each other via the local grid frequency. I've configured my inverters to ramp down from 60.2hz to 61.4hz and my Powerwall frequency max was adjusted to 62hz.

It's possible that Tesla pushed an update that has their inverters now aligned with the PW automatically rather than having to configure it "manually" like I did (I actually just got Enphase to apply a different grid config to my system). Or maybe the inverters actually talk to the PW2? Since I don't have a full Tesla system it's hard for me to guess. I believe the Enphase full system actually talks directly across the components, which is likely a much better way to do it.

 

[arnolddeleon]

They seem to have been working hard recently to allow their customers that haven't received Permission To Operate (PTO) to get decent use of their systems.

Can you check if the Powerwall is frequency shifting? Basically do you have a device that will display the frequency (Kill-A-Watt, UPS)? Obviously if you are still connected to the grid when this happening then we know that frequency shifting is NOT happening.

When you say you are running in off-grid mode do you mean you have the main breaker off or is that the mode you have in your app? Someone who also didn't have a PTO yet implied they had a mode in their app that just prevented exports.

 

[onautopilot]

There’s an option on the app now to “go off grid.” I’ve just been using that. Good idea with the frequency. I’ll check that when I fly back home next week. After 10 weeks since my permits were approved Tesla finally applied for pto with PG&E. So hopefully sometime soon I won’t have to sweat running my system.

 

[sorka]

While it's cool don't get super excited - having curtailment is not really a huge advantage over turning the batteries on and off. At the end of the day almost the exact same amount of PV is "wasted".

It would be a huge advantage for me if curtailment meant that the PW inverter output didn't exceed 60 Hz.

 

[Will792]

It would be a huge advantage for me if curtailment meant that the PW inverter output didn't exceed 60 Hz.

Is it really doable? PW grid frequency increase is the only method to communicate the need to curtail PV power production.

Somewhat disappointing that PV industry cannot come up with signaling standard to modulate power production by PV inverters.

 

[slcasner]

Is it really doable? PW grid frequency increase is the only method to communicate the need to curtail PV power production.

Somewhat disappointing that PV industry cannot come up with signaling standard to modulate power production by PV inverters.

Indeed, that's a hack that just took advantage of the fact that solar inverters were already required to disconnect from the grid if the frequency was out of range.

 

[sorka]

Is it really doable? PW grid frequency increase is the only method to communicate the need to curtail PV power production.

Somewhat disappointing that PV industry cannot come up with signaling standard to modulate power production by PV inverters.

It is doable. I'd be shocked if Tesla doesn't already have it in the works when for their own inverter when paired with the TEG.

 

[BGbreeder]

It would be a huge advantage for me if curtailment meant that the PW inverter output didn't exceed 60 Hz.

Can you explain why lit would be a huge advantage" for you? I am curious what the issue is.

All the best,

BG

 

[sorka]

Can you explain why lit would be a huge advantage" for you? I am curious what the issue is.

All the best,

BG

All of my home automation light switches fail to communicate above 60 Hz.

 

[BGbreeder]

All of my home automation light switches fail to communicate above 60 Hz.

Well that would do it for me!

Still, that does seem like an odd "feature" of the light switches to be so tightly slaved to 60.0Hz. Nonetheless, it is what it is.

All the best,

BG

 

[sorka]

Well that would do it for me!

Still, that does seem like an odd "feature" of the light switches to be so tightly slaved to 60.0Hz. Nonetheless, it is what it is.

All the best,

BG

There's some range in the operating frequency. It's about 59.8 to 60.2. Outside of that range and the powerline communications drops rapidly. In theory Insteon could design a switch that adapts to the frequency as it changes. They are all dual mode so there's wireless fallback but it's not as reliable a having dual mode working.

The oldest Insteon not only don't work but are actively killed. When my pw frequency first hit 62 Hz after a software update removed my cap, I lost 7 switches. They all died and I had to replace them. Granted they were the oldest ones and didn't have the wireless fallback.