-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Powerwall 2: Technical
- Thread starter Aussie
- Start date
-
- Tags
- Powerwall Tesla Energy
One more hiccup..
Did they hook AC condensing unit on the backup too for you? Tesla hasn't hooked mine on the backup, saying AC cannot be ever backed up. which means nothing can be TOU-shifted when one wants to turn the AC on. Which is like 70% of my use case and motivation during these summer times. The case is still open though, maybe that could be done, my CU says max 40A fuse on it. which means it probably cannot draw more than ~8kw even at its peak (customary 20% breaker derate engineering assuming). Ongoing observed draw is ~4kw which is less than some of my other uses (e.g. electric dryer) which seem to be working just fine.
Interestingly, if that's so, then AC cannot be efficiently used even with solar either. Yes one can perhaps charge solar to the battery but the house will have to be 100% on the grid while AC is still running meanwhile...
Last edited:
By the way, at least when I tried back in June, the Tesla gateway was unable to recognize the neur.io when connected via a wifi extender. Possibly it is recognizing the neur.io connection via the wifi clients list instead of the dhcp lease table. The other possibility would be if the gateway supports RS485, then something like this RS485 ethernet bridge would work (RS485 Ethernet Adapter - NET485 | Grid Connect). Honestly everything would be so much more straightforward if the units connected directly to my home wifi network (both the neur.io and tesla gateway) .
I'm a little bit surprised Tesla doesn't publish more detailed official requirements regarding max current draw and what breaker sizes should be allowed, ac, etc. Nothing prevents me from adding sub panels down the line in my house to power additional devices. Finding out that I've exceeded some backup limit after having paid for a new sub panel sounds like an expensive way to find out that there is an issue. Although maybe Tesla's solution would be to just sell you another powerwall to add on.
I'm a little bit surprised Tesla doesn't publish more detailed official requirements regarding max current draw and what breaker sizes should be allowed, ac, etc. Nothing prevents me from adding sub panels down the line in my house to power additional devices. Finding out that I've exceeded some backup limit after having paid for a new sub panel sounds like an expensive way to find out that there is an issue. Although maybe Tesla's solution would be to just sell you another powerwall to add on.
zanary
Active Member
That was one of my initial questions. If Whole Home Backup included everything (except for my Tesla Wall Connector running on 240/60). They said Yes and that's what the engineers did when they put together the quote and the design for me, and the installer said yes, that how it was designed. They also gave me the option to remove my AC (which is a 5 ton unit with compressor), but I decided to leave it on the Poewrwalls. I don't use it that often, and when I do, yes it will deplete the Powerwall pretty quickly. I don't know if it matters, but I have two Powerwall units, and I'm close to achieving the Red one in the next 80 days
I did a quick test, and when I power up my AC unit, it does surge in terms of amperage, but then settles down to 12A, so I'm not too worried right now, but if I run it on 100+ hot weather days in the SF Bay Area, then I'll be on grid for most of the day.
My average daily kWh is around 13 to 14 per day without AC. With AC on with 108 degrees weather, I achieve 50kwh for the entire day.
As for the Neur.io, I think the 1.5.1 software fixed the whole Wifi provisioning issue, and I don't see it on 1.6.0 either. I use the eero, which is not your old traditional Wifi extender, but Mesh technology. I find that Mesh is superior to the older Wifi Extender. I do use DHCP, and did not have to make any network changes to support Neur.io setup and daily use.
For the eero, I have four units in total in my house (2300 sqft, 2 floor, double-car attached garage). One downstairs near the kitchen at the back side of the house, one on the front of my house in the family room, one upstairs near in my office where my Comcast Xfinity cable modem resides, and one in the garage so that I get full coverage for my Model S, Model X and Powerwall. This way I get full overage throughout the entire house, backyard, and front of the house. With my 200/10Mbps service, I can achieve 75 to 150Mbps depending on the device (iPhone, iPad, MacBook Pro, etc...).
Hm i am 2 PWs too... why the story told is so different then... I need this on backup, it defeats the purpose, there's nothing else to eat up that ~25kwh usable supply but the AC.. Yesteray, i ran backup without AC from 7am to 11pm, washing, drying, cooking, working from home (computer etc all day) barely got down to 50% charge.. That much capacity doesn't make tremendous sense without feeding it to AC.
I think you're misunderstanding how the system works. Which loads are on the backup panel is only important when the grid is down. Those connected loads on the backup panel are the only loads that will work during a utility power failure. So, you cannot run the A/C or charge your car from your HPWC, or use other high drain devices when PG&E is down. When the grid is working normally, the PowerWall can still offset your usage and drive the meter to read zero while you are running your A/C.
zanary
Active Member
I think dlieu and I are in the same boat.
We want the entire house on "Time of Use Load Shifting" but right now with PowerwallOS 1.6.0, there's no support for that, only Whole Home Backup (if you don't have solar as is my case). That being said, I'm doing my own manual "Time of Use Load Shifting" which means that every morning at 630am I take myself off the grid (flip the main breaker) and therefore my entire usage from 630am until 11:15pm is all on the Powerwall (Quantity 2 which we both have). I have my AC (5 ton + coils) all running on the Powerwall at this point. The only thing that is not running on the Powerwall is my 60 amp Tesla Wall Charger.
In this scenario, without AC use, I am using around between 6 and 9kwh per day, and those few days I use the AC for the entire day, I can go up to 50kwh, but if I'm conservative and use AC minimal, then I'll still be within the 26kwh capacity of my two Powerwall.
I think what dlieu has an issue with, is that Tesla won't put his AC unit on his Powerwall like Tesla did mine. He would also like to run the AC off the Powerwall during his manual "Time of Use Load Shifting" scenario just like I plan to.
What I like about my setup is not that I have the entire house (excluding the Tesla Wall Charger), but that even with regular use (i.e., without AC of course), I will never use up my entire load, so during a power outage (which almost never happens), I can run two days of regular use.
Since I live in earthquake territory (SF Bay Area), if we are every disconnected from the grid due to the BIG ONE, then I'm hoping that with some pretty good conversation, I can use my two power walls to power my fridge, a few USB chargers for our iPhones, and maybe one light throughout the house, so hopefully at 0.7kw energy output, I can get maybe 20+ days of use so that we don't lose the food in our fridge... I may have my math wrong, but conversation should get us the 20+ days of use...
Gotta keep that Grey Goose in the freezer nice and cold
Okay, I was assuming that most people would have at least a small solar system. If you don't have any solar, the Tesla software and the arrangement of the backup circuits is going to be a problem. Since I have a small solar system (4.3kW DC) I can use the Self Consumption mode until 11pm, and then switch the PowerWall mode to Backup so that it doesn't drain into my EVs when they charge overnight. Then switch it back to Self Consumption so it will soak up the solar again.
.
Yes exactly what zanary said. no solar. I have two EV cars (33 EV range Pacifica PHEV minivan and Spark which i hope to replace with M3 that i hope to get before i become too old to enjoy fast cars).
i charge them with two-head J1772 Hydra plugin charger constrained to 24A (30A breaker) on subpanel (incredibly convenient and unique btw). Probably that's why they excluded CU unit: car charger in -- AC out and vice versa. Or something along these lines.
Except although it is convenient to put some charge into the minivan during the peak times, the car charger is unlikely to be the primary consumer; the primary consumer is AC in summer. Sometimes we need to charge the minivan during the day too which is nice. The assumptions are we are shifting 45 c/kwh to 12c/kwh, 10% overhead give or take. if we can shift close to 2 PWs capacity, i can hope to offset $ 5 to $8 a day, well let's say $5 avg, times 365 days, conservatively 1500 a year. SGIP step 2 $9820, project cost under 14k, then we don't really care about solar and net metering etc. etc. In reality i probably will load shift less than that -- but at least it starts making sense all the while weaning off the petroleum transportation habits more or less completely and voting for the Tesla tech with the wallet.
And so that was the thought.
But without AC and given current SGIP uncertainties it would ruin all these assumptions. The backup is a nice use-case (and actually we are motivated there too because we have prolonged power loss 2-3 times every winter due to downed lines in the canyon nearby) but it is certainly not worth 2PW alone -- neither money nor capacity.Only TOU shift does.
Well i guess once they enable TOU use case with the software, at least i hope i will be able to offset all BUT the condensing unit (i.e., including the furnace part of the AC is offset then), because right now there's no offset for anything at all while running the AC -- i am forced to switch the grid on which also causes gateway to switch to 100% grid right now for the house too. Even worse, it starts charging PW (3.3kw) meanwhile during presumably peak time and i have to switch battery switches off IN ADDITION to throwing the grid switch (after waiting enough time for gateway to realize grid change which is 1-2 mins). Big oops.
If i have to do it every time AC needs to go on or off, it becomes quite a gymnastics.
Last edited:
I just had a funny thought. What if you re-provisioned your system as though you had solar? You may not have enough CTs to do it and you may have to trick the system with some fake CT readings from your charging station, but if you tricked the system into thinking you had solar, at least you could activate the Self Consumption mode. Then the only thing you would have to do is change the mode each night and each morning back and forth from Self Consumption to Backup and back again.
Refer back to earlier posts in this thread about how to re-do the provisioning.
zanary
Active Member
That's an interesting idea. I do have access my the provisioning web site, and I'm familiar with the 10 screens, except for the screen that ask for CT, I'm not too sure what to fill in there to fake it.
Do you have a screen shot of this screen and what it should be if we were to fake it with Solar so we can do Time of Use Load Shifting in the app vs going outside and flipping the breaker twice a day?
zanary
Active Member
Wow. Very Cool. I'm still on 1.6.0 as of last night. I'm wish Tesla would publish release notes for PowerwallOS so we know what's in each update... I'm hoping that Time of Use Load Shifting arrives with 2.0 by December 31st as they have indicated.
eml2
Member
I had my 2 Powerwalls installed a week ago. At first it showed 1.7.0, a few days later, it was downgraded to 1.6.0!
As far as I can tell, with 1.7.0, when I connect locally to the Gateway's web UI, it shows the Powerwall output/input power (kW), like those for solar/grid/home. No long shows it with 1.6.0.
Could you please point me approximately to the page #? i searched the whole thread for "provision" keyword but found nothing about how to get to those screens? Also tried to just do general search outside the thread, nothing that would resemble such a hack.
But that's similar to what i thought. All we need is just schedule that switches between self-consumption with 20% backup (day) and back to backup (100% backup) at night... Seems like something that is already there, less the preconfigured scheduler. But i would be quite ok with a software switch if it means i dont have to switch the grid off and have discharge as a priority during the day...
Thanks!
P.S. oh.. you mean the port 80/wizard of the gateway? it is password protected, it seems..
Last edited:
eml2
Member
I have 2 Powerwalls directly hooked up to the main panel (as whole house backup). I also have two 3 ton AC units. Without the grid, no even one compressor can't start. It seems that the voltage drop is too much for the compressor to handle. With the grid online, both can be started and run on the 2 Powerwalls.
The post seems to be missing. If you Google "Powerwall password site:teslamotorsclub.com" the first result shows the post, but only if you look at the cached version. TLDR: it's the unit's serial number.
... Also one more extremely annoying thing to report...
if one uses powerline networks, switching to backup causes power drop enough to jam some of my powerline adapters for good.
And since the only way to reset them seems to unplug and plug again, and all the devices are plugged into it for the sake of its pass-thru power noise filter, it also means that i have to reset all these devices -- routers, my synology NAS, etc. etc., of which i have a ton.
Again, once the TOU scheduler is implemented to switch gateway between backup and discharge modes, i hope this will not be that bad, since gateway does not have to detect the grid outage, and so it can orchestrate the switch more smoothly with 0 power drop during the transition.
So TOU update can't come soon enough for me
if one uses powerline networks, switching to backup causes power drop enough to jam some of my powerline adapters for good.
And since the only way to reset them seems to unplug and plug again, and all the devices are plugged into it for the sake of its pass-thru power noise filter, it also means that i have to reset all these devices -- routers, my synology NAS, etc. etc., of which i have a ton.
Again, once the TOU scheduler is implemented to switch gateway between backup and discharge modes, i hope this will not be that bad, since gateway does not have to detect the grid outage, and so it can orchestrate the switch more smoothly with 0 power drop during the transition.
So TOU update can't come soon enough for me
Last edited:
