Strategies for Powerwalls and Utility Demand Plans

[Darwin]

This is awesome. So how exactly does the algorithm work? Assuming all 4 thermostats are set to 80 degrees and all 4 zones get to 81, does it just get Zone 1 down to 80, then shut it off, then turn on Zone 2 let it get to 80, etc?

I signed off on getting the Powerall 2. Hopefully even though I don't have solar c ombined with your Demand Manager App it'll still help me w/ my demand charges. So other than the Powerwall all I need is the SmartHub, correct?

Congrats on your founder's PW2. I'm interested in hearing how the Powerwall works for you for demand management without solar.

The demand management app right now is more reactive than proactive. You choose a demand max kW goal that you would like to not exceed, say 5 kW. The app continuously projects out your 30 or 60 minute cycle (60 minutes for APS) kW demand based on data from your connected home energy meter (in your case the will be the PowerWall).

If at any time during peak hours the app projects that you are going to exceed your 5kW demand goal by the end of your 60 minute cycle period, it will look at all of your currently cooling smart thermostats and turn off one of them by raising the temperature. I kept it simple for now and the app will not turn off two different thermostats in the same 60 minute demand cycle. I can modify this behavior in the future, but didn't want to add too much complexity all at once. If that same thermostat comes on again in the same hour though, it will turn it off again. You can choose whether to have the app return the thermostat back to its original temperature at the start of the next 60 minute demand cycle or just leave it at the higher setting until peak hours are over for the day. The intent with the latter option is to pre-cool your home prior to your peak period, and then let the app gradually raise the temps as needed (up to a maximum preference setting) through the end of your peak period.

If in a later 60 minute demand cycle the app again projects that you are going to exceed your 5kW demand goal, it will again sequentially evaluate all of your running thermostats, and if possible, it will choose a different thermostat to turn off than the one it chose the last time.

I see some potential pitfalls with how this simple multiple thermostats capability works right now. I'm sure there will need to be updates. Since I only have one AC unit, I really can't test much of this.

Since you'll already have a Powerwall acting as your home energy meter, you'll just need a SmartThings hub (the one you posted will work) and SmartThings compatible, smart thermostats on all your AC units. Ecobee's work well, but since Google just ended their Works With Nest program a month or so ago, I don't believe Nests will work anymore unless you've already set them up with SmartThings before Google closed off the API.

 

[Chancellor32]

Has anyone with a solar powerwall ever seen a path to charging from grid? I too am on SRP, and the ideal scenario would be to charge powerwalls from grid overnight, and use it to shave demand during the day. A product manager has suggested that this capability may become present when the solar tax incentives go away.

From the utility connection documents, it looks like the backup gateway only manages the grid interconnect, and not the power flow between the powerwall and the solar panels. Since the powerwall could be connected to grid in a standalone arrangement, what is the interconnect device that limits charging to the solar array? Is this connection made in the inverter? What prevents the powerwall from being grid charged?

Yes you can charge from grid, it’s called giving up the tax credit. Ideally you could go on E27P and just use 1-2PW’s to cover all demand during peak time.

 

[jbbjbbjbb]

Yes you can charge from grid, it’s called giving up the tax credit. Ideally you could go on E27P and just use 1-2PW’s to cover all demand during peak time.

From what I can tell, if I order Powerwalls from Tesla and have solar, I can't configure it to charge from grid. Just posted a response to another thread just now regarding 3rd party certified installer somebody used in California for just the Powerwall, as an add on to existing Tesla solar, and whether the third party offered more flexibility on the powerwall installation.

 

[Chancellor32]

From what I can tell, if I order Powerwalls from Tesla and have solar, I can't configure it to charge from grid. Just posted a response to another thread just now regarding 3rd party certified installer somebody used in California for just the Powerwall, as an add on to existing Tesla solar, and whether the third party offered more flexibility on the powerwall installation.

Yeah if you have solar then charging from the grid is a no go, at least for now until the tax credit goes away. If you have no solar then the PW can charge from grid, my buddy has 2 and it works well for him.

 

[Rahul]

...
Since you'll already have a Powerwall acting as your home energy meter, you'll just need a SmartThings hub (the one you posted will work) and SmartThings compatible, smart thermostats on all your AC units. Ecobee's work well, but since Google just ended their Works With Nest program a month or so ago, I don't believe Nests will work anymore unless you've already set them up with SmartThings before Google closed off the API.

Ugh, I have 3 Nests and 1 Ecobee. Any thoughts on how to get demand management outside of swapping my Nests for Ecobees?

 

[miimura]

Ugh, I have 3 Nests and 1 Ecobee. Any thoughts on how to get demand management outside of swapping my Nests for Ecobees?

The brute force way to make sure that only one A/C compressor runs at once is to put a relay in-line and interrupt the Y wire that commands the compressor to run for the units that you want to delay. However, it won't keep the air handler from running needlessly.

 

[jbbjbbjbb]

Ugh, I have 3 Nests and 1 Ecobee. Any thoughts on how to get demand management outside of swapping my Nests for Ecobees?

What stops you from retrofitting a demand manager to your panel after the install?

 

[Chancellor32]

Ugh, I have 3 Nests and 1 Ecobee. Any thoughts on how to get demand management outside of swapping my Nests for Ecobees?

I don’t think it’s possible with nest now that google has locked down the 3rd party access. This just happened as of August 31st.

 

[Darwin]

Ugh, I have 3 Nests and 1 Ecobee. Any thoughts on how to get demand management outside of swapping my Nests for Ecobees?

I don’t think it’s possible with nest now that google has locked down the 3rd party access. This just happened as of August 31st.

Yes - unfortunately, I don't think Nests are going to work anymore for new users unless/until Samsung/SmartThings works something out with Google. There are other cheaper SmartThings compatible Z-Wave thermostats in the $75 range but they're not as nice as the Ecobees and I am not sure anyone has tested the Demand Manager software with them yet. Even with just one thermostat connected to the Demand manager though, it should help somewhat since at least all thermostats won't be cooling at the same time. I'm not sure how bothersome it will be though if it's always the same thermostat that gets shut off in response to demand events. You can try it with just one thermostat and if the app seems to be working for you, you could choose to swap out another thermostat in the future. Just having two connected therostats may be OK for your needs.

The bigger question may be how one PowerWall is going to work for managing demand with 4 AC units, since the Powerwall currently has no option for demand shaving. It's currently an all-or-nothing prospect - and one PowerWall without solar obviously won't last long powering 4 AC's.

One thought is to use the SmartThings Powerwall Manager app to gradually reduce the reserve percentage every hour so that you can be assured there will always be some juice in the battery to cover some of your demand every 60 minute demand cycle. So, for example if your peak hours are 3pm-8pm, you could first pre-cool your home prior to 3pm so that your AC's won't need to run much if at all the 1st hour or so, and then schedule your Powerwall in the Tesla app for aTBC cost-saving shoulder period from 4-8pm. Then in the PowerWall Manager SmartThings app, set up 4 reserve percentage schedules for 4pm: 75%, 5pm: 50%, 6pm: 25%, 7pm: 0%.

If it all somehow successfully works together, you may be able to shave off 3-4 kW from your summer peak hourly demand charge as well as load shift ~15 kWh daily into off-peak.

 

[vordo]

I am new to all this - My Powerwalls are currently being installed and will start playing around with integration soon. I too have a raft of NEST's and would be loath to swap them out. It occurs to me that Smarthings has a IFTTT channel - as such couldn't @Darwin's powerwall integration allow Smarthings to send - grid on/ off status to IFTTT and control the NEST's that way?

 

[Davidja92]

First and foremost thank you for these apps they work amazing I’m just using the powerwall manager app and the changes reflect very fast. Is there a way possibly to add in a feature that can show your net cost of buying electricity from the grid and a net savings of using the battery or selling back to the grid where users can add in tou prices based on what they pay? It be cool to see how much we spend and save.

 

[Darwin]

First and foremost thank you for these apps they work amazing I’m just using the powerwall manager app and the changes reflect very fast. Is there a way possibly to add in a feature that can show your net cost of buying electricity from the grid and a net savings of using the battery or selling back to the grid where users can add in tou prices based on what they pay? It be cool to see how much we spend and save.

Thanks for the feedback. That's a great idea. It would be very handy to have a way of viewing actual cumulative savings achieved using the Powerwall and/or solar from a production and load shift (and maybe even a demand fee) perspective. I'll add it to the list of potential enhancements and give it some thought.

 

[Davidja92]

Thanks for the feedback. That's a great idea. It would be very handy to have a way of viewing actual cumulative savings achieved using the Powerwall and/or solar from a production and load shift (and maybe even a demand fee) perspective. I'll add it to the list of potential enhancements and give it some thought.

you are amazing at what you do if I new code and how to do stuff like this I would definitely contribute. I gotta start watching YouTube to learn these things...on a side note if I switch to self powered would that fix the random grid spikes when the powerwall is ramping up to handle usage spikes? Right now I’m on tbc cost savings and if I have a usage spike the grid kicks in while the battery ramps up then the powerwall takes over.

 

[Darwin]

you are amazing at what you do if I new code and how to do stuff like this I would definitely contribute. I gotta start watching YouTube to learn these things...on a side note if I switch to self powered would that fix the random grid spikes when the powerwall is ramping up to handle usage spikes? Right now I’m on tbc cost savings and if I have a usage spike the grid kicks in while the battery ramps up then the powerwall takes over.

Thanks. Really appreciate it. Yes, I've found that self-powered does a better job than TBC Cost-Saving as far as quickly ramping up to cover usage spikes. I've been using the Powerwall Manager to define Self-Powered mode schedules to match my utility peak periods and it has eliminated that last vestige of usage/demand I was still seeing during peak hours. It definitely adds some reliability risk though, since the PowerWall Manager is dependent on a 100% operational SmartThings cloud, Tesa cloud, and your local internet.

 

[blueice89]

Hey guys you can read my write up on automating back up mode :

Automated back up mode with python and rest

You would be proud of me Darwin I used windows scripting and python turn on and off back up mode now I can control when full solar charges battery . In need to do a larger write up but here is code and pics : I do think I have to many schedules define since shoulders Define off peak.

Python :
I found a python API as well. This actually worked a lot better, just made few tweaks on the username / password. etc, and then added these as schedule tasks in windows machine to run at 9am and 9pm.

Python :
I found a python API as well. This actually worked a lot better, just made few tweaks on the username / password. etc, and then added these as schedule tasks in windows machine to run at 9am and 9pm.

piersdd/tesla-powerwall-json-py

Then my fork :
My mods are located here:
CodePile | Easily Share Piles of Code

did you know you could use teg controller and make rest calls to it game changing ::
vloschiavo/powerwall2

 

[Rahul]

Yes - unfortunately, I don't think Nests are going to work anymore for new users unless/until Samsung/SmartThings works something out with Google. There are other cheaper SmartThings compatible Z-Wave thermostats in the $75 range but they're not as nice as the Ecobees and I am not sure anyone has tested the Demand Manager software with them yet. Even with just one thermostat connected to the Demand manager though, it should help somewhat since at least all thermostats won't be cooling at the same time. I'm not sure how bothersome it will be though if it's always the same thermostat that gets shut off in response to demand events. You can try it with just one thermostat and if the app seems to be working for you, you could choose to swap out another thermostat in the future. Just having two connected therostats may be OK for your needs.

The bigger question may be how one PowerWall is going to work for managing demand with 4 AC units, since the Powerwall currently has no option for demand shaving. It's currently an all-or-nothing prospect - and one PowerWall without solar obviously won't last long powering 4 AC's.

One thought is to use the SmartThings Powerwall Manager app to gradually reduce the reserve percentage every hour so that you can be assured there will always be some juice in the battery to cover some of your demand every 60 minute demand cycle. So, for example if your peak hours are 3pm-8pm, you could first pre-cool your home prior to 3pm so that your AC's won't need to run much if at all the 1st hour or so, and then schedule your Powerwall in the Tesla app for aTBC cost-saving shoulder period from 4-8pm. Then in the PowerWall Manager SmartThings app, set up 4 reserve percentage schedules for 4pm: 75%, 5pm: 50%, 6pm: 25%, 7pm: 0%.

If it all somehow successfully works together, you may be able to shave off 3-4 kW from your summer peak hourly demand charge as well as load shift ~15 kWh daily into off-peak.

@Darwin I finally got my Powerwall operational today after all this time. Does your PowerWall Manager SmartThings app still have the capability of reducing reserve as you mentioned in the above post? The reality is that I only have 2 zones I really care about during peak time. Currently I have thermostats setup so both zones supercool till 3. Then only zone A is set to stay cool from 3p-4p and zone B temp goes up. Then from 4p-5p zone B temp goes down and zone A’s temp goes up. I repeat this cycle once more to get to 8p. If I can do that reserve drop as you describe it should help me a lot. Let me know and I’ll order the SmartThings device.

Thanks!

 

[Darwin]

@Darwin I finally got my Powerwall operational today after all this time. Does your PowerWall Manager SmartThings app still have the capability of reducing reserve as you mentioned in the above post? The reality is that I only have 2 zones I really care about during peak time. Currently I have thermostats setup so both zones supercool till 3. Then only zone A is set to stay cool from 3p-4p and zone B temp goes up. Then from 4p-5p zone B temp goes down and zone A’s temp goes up. I repeat this cycle once more to get to 8p. If I can do that reserve drop as you describe it should help me a lot. Let me know and I’ll order the SmartThings device.

Yes, the Powerwall Manager app can currently support up to 7 different schedules for commands to the Powerwall to include Reserve % updates. One concern though is with how long it takes the Powerwall to respond to the reserve % command change. With the recent Powerwall firmware updates, I know things have gotten much better with Powerwall response times, but I'm not sure how much. Most users I know generally avoid commanding the Powerwall with the app during peak TOU hours simply because the Powerwall can briefly stop discharging when changing states. Since your single PW may not have enough juice to cover your entire peak period anyway and your goal may be to shave only a % of your demand each hour vs 100% TOU power coverage, a brief interruption period may not an issue at all for you. I can try to do some testing on how long it takes the PW to react to reserve % changes, but maybe someone here has some recent experience with this.

The Powerwall Manager app is capable of running on both the SmartThings Hub and the Hubitat Home Elevation Hub if one hub strikes your fancy over the other. Both are pretty slick little devices in their own right each with their unique pros and cons (and unique outspoken fans and critics).

Tesla Powerwall Manager app for SmartThings (and Hubitat) Hubs - DarwinsDen.com

 

[cwied]

In my experience reserve % changes when in self-consumption mode usually complete within a minute. I've had mixed results with changes when in time-based control mode. Sometimes it seems like changes are quick, at others it seems like it took more than a few minutes before the change was picked up. I wasn't always changing just the reserve, though, so more experimentation is probably warranted.

 

[Rahul]

I just ordered the SmartThings Hub. In the first hour of on-peak usage about 28% of the batt drained out with just 1 unit running. I need to read up on how APS exactly calculates the demand over the hour. It seems to me if it's on every hour, then maybe I just set it to:

• 80% @ 3p
• 60% @ 4p,
• 40% @ 5p
• 20% @ 6p
• 0% @ 7p

Thoughts?

 

[Darwin]

I just ordered the SmartThings Hub. In the first hour of on-peak usage about 28% of the batt drained out with just 1 unit running. I need to read up on how APS exactly calculates the demand over the hour. It seems to me if it's on every hour, then maybe I just set it to:

• 80% @ 3p
• 60% @ 4p,
• 40% @ 5p
• 20% @ 6p
• 0% @ 7p

Thoughts?

This schedule looks good to me for APS 3pm-8pm peak hours. You'll also want to add a return to 100% probably at 8pm. I'm really interested in how this works out from a demand shaving perspective. Good luck!