That is where it would be cool, and i haven't had enough time to look into this where one of those smart panels could start shedding loads based on the SOC of the power walls.
It’s an interesting idea, but it gets complicated very fast. For example, the logic really needs to be based on more than just the powerwall SOC. For example, I could have it configured to shut off my air conditioner if the SOC goes under 20%. But if that happens at 10PM because I didn’t get enough solar power to fully charge my powerwalls then it’s going to be too late and the powerwalls won’t make it through the night anyway. On the other hand, if the powerwalls hit 20% at 6AM, then the AC doesn’t need to be turned off because the sun is going to come up in an hour and the powerwalls will have no problem supporting my AC for that last hour with 20% of their power remaining. At the minimum you would need to look at the SOC, the time of day, and if you wanted to get really fancy, maybe even the amount of solar power received that day and the amount of solar power you expect to receive the next day.
There are still some things that can be done with an automation system that’s getting outage data from the powerwalls. For example you could say that whenever the power fails then turn off the pool pump and raise the thermostat by 2 degrees so the AC isn’t using as much power.
But even with that sort of logic the length of the outage (if known) can affect these decisions. If my power is out because of a hurricane then I know that it’s likely going to be out for multiple days and I would want my system to react so that it can conserve power. But if the power is out for another reason and I can see that my utility is predicting that it will only be out for 3 hours then I probably wouldn’t want to make many or any changes to reduce my power consumption because I know my powerwalls will have no problems getting through that short outage.
There’s a great plugin for HomeSeer that was written by
@gpez that allows the HomeSeer system to see the a lot of info from the powerwall, including the grid connection state, the powerwall SOC, as well as a prediction of the amount of powerwall runtime remaining based on a rolling average of power demand over the last X minutes.
I’ve spent some time thinking about it, but so far I haven’t really configured any events to respond to power outages yet just because it tends to get complicated very quickly. While there might be cases when I could want the system to shut down my AC if my powerwalls won’t make it until sunrise I also need to factor in the fact that here in Florida it starts to get pretty miserable pretty quickly if the AC is shut off. In a more northern climate it might be easier to let the system shut off the AC when the power fails, however, the flip side of that is that in a more northern climate the AC might not be drawing that much power anyway, so shutting it off wouldn’t really make much of a difference.
Another factor for me is that I bought 4 powerwalls so that I could continue to run my house pretty close to normally even during an extended outage. For someone with only 1 or 2 powerwalls then it might be more critical to shed loads to try to maximize the power that they do have.
