Question for SRP customers in the Phoenix metro that have solar and Powerwall

[Kat-A-Tonic]

Hey all-

I have had solar and Powerwall for about 4 years now and have SRP as my energy provider. I have an issue that I cant seem to solve. Right now, my Powerwall runs the entire house during the "Peak" hours and exports all of the solar I generate back to the grid. I do not feel that this is good for the batteries, and it is really bad for my reserve power in case of a blackout. My batteries are depleted to 35% every day assuming I do not run major appliances other than the smaller of my two air conditioners. Can anyone tell me how to set up the app so that the Powerwall just augments solar to fully run the house during the peak hours on my SRP plan? I realize that this will cut down how much I export during the peak, but there is not enough price difference in the credits to justify the increased battery usage. I am looking to use solar and the grid to run the house during off peak times, and solar and the Powerwall to run the house during the peaks so that there is no demand charge on my bill.

 

[jjrandorin]

Perhaps I am not understanding, but why not just use self powered mode? Self powered mode will only export solar if both your powerwalls and your home cant take the solar power, and it does that at all times.

It only starts draining your batteries when your solar doesnt cover your house load, then, it supplements the solar with powerwall power till solar is gone, then uses powerwall power, until it hits the reserve you set.

If you dont care about price deltas etc, it sounds like thats what you want (its what I use, self powered mode I mean).

 

[Kat-A-Tonic]

I need to NEVER use any power during the SRP peaks. I do not know how the self power mode works, but I think it could draw power during a peak after the sun is low enough where solar no longer produces enough to run the house. I would like to just set a timed schedule that has the house run on solar first and the Powerwall fills in any shortfall from 2:00 PM to 8:00 PM in the summer.

 

[jjrandorin]

I need to NEVER use any power during the SRP peaks. I do not know how the self power mode works, but I think it could draw power during a peak after the sun is low enough where solar no longer produces enough to run the house.

Self powered would only pull from the grid if you both didnt have enough solar power to power the house AND either didnt have enough powerwall power or it hit the reserve.

I would like to just set a timed schedule that has the house run on solar first and the Powerwall fills in any shortfall from 2:00 PM to 8:00 PM in the summer.

I dont personally use time based control because I dont like any of the "algorithm," stuff. Perhaps you could get to where you wanted with tweaking your buy and sell prices, but I dont have any experience with that myself. Perhaps some others who use Time based control mode could help you with that.

If you were ok with using third party apps, perhaps you could setup something to toggle from time based control to self powered during your peak time of 2pm to 8pm, but then I dont understand the purpose of using time based control in the first place (but thats likely because I dont use it even though I know what the purpose is for in general).

 

[BGbreeder]

I need to NEVER use any power during the SRP peaks. I do not know how the self power mode works, but I think it could draw power during a peak after the sun is low enough where solar no longer produces enough to run the house. I would like to just set a timed schedule that has the house run on solar first and the Powerwall fills in any shortfall from 2:00 PM to 8:00 PM in the summer.

As @jjrandorin pointed out self powered could do this, but so could time based control. In both cases, you would start by choosing one, and setting your utility power schedule weekday & weekend, plus summer and winter if there are differences. The algorithm may take a few days to settle in, but it should do what you want, provided, of course, that you have sufficient reserves.

Personally, I have found that if the buy/sell prices are different by at least 10%, and preferably 20%, that the algorithm seems to converge on the desired behavior of not consuming grid power during peak periods a little more quickly. YMMV.

There has been quite a bit written here on TOU rate management with self powered and time based control. You might find it helpful to read some of those threads.

All the best,

BG

 

[Kat-A-Tonic]

I guess it is just too hard for Tesla to come up with something that just uses time. The app is always trying to do something "smart" and creative instead of just avoiding any use during the peaks. I may try to switch to self powered and monitor it, but I really do not want to pay the crazy demand fee for 1/2 hour of a mistake.

For example, I can't seem to get the Powerwall not to discharge on the weekends without manually setting the reserve to 95 percent. I do that every weekend, then have to remember to switch it lower for the week days.

Does anyone know how to get someone at Tesla on the phone that could maybe figure this out?

 

[dareed1]

I use NetZero which offers Powerwall automation. It coexists with the Tesla app. As an example, in my case I use self-powered mode and the automations are set up to change the Powerwalls' reserve to cycle between 95% and 20%. The event that triggers setting the reserve to 95% is the onset of car charging, which is itself triggered by the Tesla App at typically 4AM or so. When the charging has completed (at 7AM, since the Tesla app allows scheduling the charging completion time) the NetZero automation set the Powerwall reserve to 20%. We have whole house backup, and this allows me to use the Powerwalls to run the house except when charging the car. With whole house backup, car charging would drain the PWs if the reserve were not set to a high level.

The NetZero automations are operated from the cloud, and they can be managed either from phone or web browser. If you doubt that the automations will execute correctly, you can set them to run in test mode which won't actually change PW settings. So you wouldn't need to worry about demand charges.

In your case, as I understand it, you'd set up self-powered mode, and add two automations. One would set PW reserve to, say, 20% at 2PM on each selected day, and the second would set the reserve to around 100% at 8PM. Actually, although you don't say this exactly, I'd want the reserve left at 20% or other low value until 9AM or so when solar is likely to kick in. In self-powered mode with a very high reserve, solar generation will power the house first, fill the PW second, and export after the PW is full if the generation exceeds the house load. But the PW won't power the house if the state of charge falls below the reserve.
With the reserve at low values, solar will power the house first and the PW will supply additional power if the house load exceeds the solar generation. If the PWs reach 100%, and generation exceeds the house load, the Gateway will export. Of course if the PW state of charge falls below the reserve value and the load exceeds the generation (like at night) then you'll draw from the grid.