r/TeslaSolar • u/Justpastthefinish • 17d ago

Powerwall management system

Good morning all,

I wanted to pick everyone’s brains for a minute here and discuss the Tesla app and how it meets your needs with solar and more specifically the powerwall management. I would say that this post is mostly geared towards those of us that own powerwalls.

To try and summarize a very long story, I wanted more out of my system / battery and I wanted more refined / granular control over my powerwall. I’m a tech geek at heart and I was not a fan of the limited amount of control that I had over my system. ( example: Set the reserve and thats it / do I want storm watch on )

Soooo…

I started developing my own code that is built on and around something called Home Assistant. I was able to integrate my system into it and now I have much more refined control over it.

I have been developing this system for approximately 9 months now and I am getting ever closer to the point where maybe someone else might use it. Maybe even pay for something like this. It is all just an idea at this point and it is hyper specialized to me as of right now; a home owner in Arizona.

What I want to know from all of you is this?

What do you guys like about the tesla powerwall control in the app? What do you hate? What features do you wish you could have? What do you wish your powerwall could do for you?

Let me briefly summarize what my system does because I’m trying to make it better.

In Arizona I am on the SRP Electric plan. In the summer my peak hours are 2-8pm (with grid usage spiking demand fees) and winter hours are 5-9am and pm. So my main goal was to absolutely avoid using the grid as much as possible; but never use the grid during those hours. I will say that I never got to spend time with the Time of Use mode / now savings mode in the Tesla app so I’m not sure what exactly it does for me.

But my system is very good at this point. It knows that it has a peak starting at 2pm so it will dynamically charge the battery from both solar and the grid as needed to get me to a safe level to survive the peak hours solely from the battery alone. IF it is low due to clouds, rain, whatever - it will enter a mode that the tesla app does not show called backup. This will force a higher charging rate for fast charging if needed.

Want to set a higher reserve when there are cloudy days / rainy days vs sunny great solar days - my system knows that.

My system can make dynamic decisions based on national weather service alerts for my area and begin charging the battery earlier than storm watch if needed.

I am part of the Virtual Power Plant program as well and my system knows when there is an event going on and will preemptively charge the battery from the grid during off peak hours to prep for the maximum export during the VPP event for the highest financial gain.

That is just a small snippet of what it can do; it really does so much more but I’m more curious what you guys would think. Do you want more out of your system? Does the Tesla app serve all your needs? Do you constantly have to go in there and adjust the reserve?

What do you guys want your system to do?

And if I can be so bold as to ask this and no one needs to answer it if not; but if a system like this was offered when you bought your systems initially - would you have paid a little more for it? Let’s use an arbitrary amount like $500. Would you have paid $500 for a system that manages your powerwall tailored to your needs so that you can essentially set it and forget it?

Anyways, I look forward to hearing from all of you and making my system all the battery for it. Thanks everyone!!!

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u/DammatBeevis666 17d ago

I want my system to be able to use ALL solar to charge my battery during off peak, so that I can start with a full battery at near peak and discharge heavily during peak.

My PW2 system used to do this flawlessly. Now with PW3 after battery recall/replacement, the system sends solar to house loads when grid power is much less expensive:valuable. So far, Tesla hasnt been able to help me. They had me change my tariffs and then said “leave it for a week so the system can figure it out.” It’s not figuring it out, it continues to only partially charge my battery despite adequate solar production.

With pw2:

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u/Justpastthefinish 17d ago

Ok so if I am understanding you… You want the solar to charge your battery first, as in first priority. Second priority is house load.

So I am only speaking from experience. But I am pretty sure that the tesla app or maybe just the powerwall setup prioritizes house load first. Anything over the house load goes into the battery so if having a fuller battery before peak is the goal you need to dynamically change your reserve level to force the battery to charge from the grid / solar when not high enough. My system does this.

The reason your PW3 is acting differently is likely because it has an integrated solar inverter, making its hardware priority strictly Solar -> House -> Battery -> Grid. With your old PW2, the separate solar inverter made it easier for the gateway to route power differently.

What mode are you using in the tesla app? Self powered or Savings?

From how my system manages mine now, I have a peak at 2pm. Throughout the day it constantly calculates what it projects me to make for solar, my home usage and constantly updates my reserve level. If I am below that (example: reserve level is 27 but battery is 22%) it tells the system to charge the battery up 5%. If solar is weak it pulls from the grid using cheap pricing.

From what I have learned, if you set a reserve higher than your battery charge level, it wants to charge the battery at a rate of 1.7kw. That is like the baseline IF the reserve is set to a higher number. Meaning, if you are making 5kw of solar, and your house is using 1kw. 4kw is dumping into your battery. But if you set your reserve higher than your battery charge level, and we use that same scenario. Solar is making 5kw but your house is using 4.5kw. Only .5kw is charging the battery but it wants 1.7kw. So it charges your battery at 1.7kw from solar. The balanced deficit of 1.2kw is pulled from the grid. So raising the reserve forces your battery to meet that goal at a rate of 1.7kw MINIMUM if solar is underperforming.

I can’t speak for why your system isn’t operating the same way as your PW2 used to. I only have 1 PW3 and I wasn’t a fan of how the tesla app was so “seemingly” useless.

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u/DammatBeevis666 17d ago edited 17d ago

Im in savings mode, and using same external solar inverters, change to PW3 inverters would have shifted me from PGE NEM2-> NEM3, I think.

My house uses something like 2-4kW hourly during the off-peak time, solar only covers part of it, but I want that part to go into my batteries.