Energy Products

Tesla Forums are now read only. To continue the conversation with the Tesla community visit

Powerwall algorithm is not good enough


i own a powerwall in the UK as as we move into winter i am fed up with waking up in the morning to see that the powerwall has not charged overnight.

I have been through support with this already and am told that the algorithm needs to "learn my system". Well i'm sorry but this just doesn't cut it.

Why on earth can't i just tell my powerwall to charge up to a certain level every night on my cheap rate electricity because this is what i need to be able to do. And, frankly, this is what i thought i was getting.

There's no way on earth someone can write an algorithm that can predict my energy usage properly. Even if you tie the system into the local weather forecasts i live in a coastal region where the forecasts are frequently wrong and even if they were right, it's still not good enough.

I have an electrical heating system (air source heat pump) and i need to ensure that my battery is charged adequately, every night, so that the following day i maximise the usage of my low cost electricity.

And what happens if i'm away for a few days, or a holiday, does the algorithm learn that "hey, this guy's not using much power, let's not charge up at all!". Whereas the reality is that ifi had the ability to define when and by how much the powerwall charged up i could have the system ready and waiting for me upon my return. And vice versa, I can tell the system not to charge at night when i'm away up to the day before where it can charge from the mains electricity.

I ask that you give us, your customers, the ability to do this please. Give us the choice - if people are happy with the algorithm then fine, leave the box checked - call it "automatic learning" or something. But for goodness sake stop trying to be so clever because it just doesn't work for people like me, where i live.



  • edited October 2019
    You’ve got my vote! I’ve also requested it!
  • edited October 2019
    Across the pond (USA), it's actually against the law to charge a Powerwall from the grid, except in weather emergencies via the Stormwatch function. PWs can only be charged from solar, during the day. The utilities don't want customers using the TOU tariff differential to make money by time-shifting. In Australia, for example, one *is* allowed to charge from the grid. You might want to check with your local laws to see if charging from the grid is even allowed in the UK.
  • edited November -1
    Did you check your Tesla App?
    Do you have an Option called Advanced Time Based Control?
    In the US we can only charge the PowerWall from the Solar if using Time Based Control. The only way to charge from the grid is if in backup mode...
  • edited October 2019
    US utilities won't allow you to charge PWs from the grid...even in "Backup" mode. PWs can only be recharged from PV.
  • edited October 2019
    There's no issue charging from the grid in the UK and we all have the Time based controls here, the issue is the Algorithm that controls the Time based controls which works by learning the historical usage and weather, it just doesn't work in a climate that has unpredictable weather where everyday is different. Some manual control is all we ask.
  • edited October 2019
    Tesla PW can be installed with or without solar. With solar, the PW only charges from the grid in emergency modes such as Storm Watch.
  • edited October 2019
    Passion2Fly, As I noted in my first post of October 10th.

    Beeza, Time-based controls in the USA are set by the user. It's not a matter of the TEG learning behaviors and adjusting itself (like a NEST thermostat), but the user sets the behaviors of the PWs according to when TOU tariffs change. I hadn't heard that the TEG firmware allows for learning behaviors. Very interesting. I wonder if something like that will be rolled out in the States...
  • edited October 2019
    There is only one "smart behavior" which I'm aware of in Time based control. The system "makes room" for energy storage if the super off peak times fall during sunlight...
    In San Diego, SDGE has weekends super off peak from 12AM-2PM. During the week is 12AM-6AM. Obviously, the super off peak are not during the maximum solar radiation. So, every Friday and Saturday, my time based algorithm empties the battery all the way down to "emergency reserves", so I can charge with solar on Saturday and Sunday... It doesn't do that Mon-Fri... It's cool, I like that. It's a smart use of what's called "shoulder rates" (between on peak and super off peak).
  • edited October 2019
    I'm also in the UK and have recently experienced the same issues as cankfarm, with the battery starting the day at levels as low as 15% with little prospect of much solar due to rain and cloud. I don't think the algorithm uses any weather data, such us predicted number of hours of sunlight in your location, so being able to set a minimum level by the end of the off-peak rates would be very helpful. Having said that, I've had my Powerball 2 for just over a year and it has done a great job of managing the power, BUT I've noticed a big change over the last few weeks which has resulted in lower power levels in the battery and many periods when incoming PV has been sent to the grid rather than charging the battery. Today for example despite over 3kw coming from the roof and little power being used in the house (we were out) the battery sat at 58% for about two hours while all the power was sent to the grid. In the past all excess power was sent to the battery until it reached 100% then it would export to the grid. I think the algorithm has been 'updated'. When I phoned support they said the Tesla App shows incorrect data. If that's true then how can we know what's actually going on?
  • edited October 2019
    @Passion2Fly, what if there is no solar power on Sat and Sun and batter ran itself down?
  • edited October 2019
    @alanjenglish : that is a lousy excuse from Tesla How does he know it is incorrect, does he have the correct data? Have him update your data in the battery then ;)
  • edited November 2019
    ok folks so i've not replied in a while as I feel that other than guaging whether other people are getting the same problem (or if there's a magical solution) then the people that matter within Tesla just don't give a damn/notice what people are reporting on the forums. Happy to stand corrected but there you go.
    I will impart additional information that i have found out but my current barrier is first line support. Don't get me wrong, they're very helpful and understand the issue but the most i can do is get them to send a "feature request" to Tesla. I have no idea if this request is being considered but apparently this is the most requested feature from UK users. I am currently trying to get additional information out of my supplier and the Tesla footprint in the UK generally and will report back if anything useful comes up.

    So firstly it's importatnt to point out to people in general and especially our friends in the US that this is specifically a UK issue because, as was previously pointed out by gregbrew, you can't charge from the grid - it's solar only. In the UK we can set the "time based control" to reflect our off peak electricity hours and as the much vaunted Tesla literature states, we can then power our homes from cheap electricity during the day. That is a lie because this stupid algorithm seemingly ignores our actual energy usage. Now i understand if it works well for you but my house is run entirely from electricity - cooking, heating (air source heat pump), water, the lot. So i need that battery charging up fully at night, or at least 80% or something.
    The problem is that most of the time it does not and it definitely will not if you happen to get some solar on a partiicular day. I've had this confirmed by support - if you get solar on one day, and irrespective of your power usage on that day, the powerwall will charge little or nothing during off peak because, and get this, it assumes that you'll get solar the next day. WHAT? How utterly stupid is this for a climate (in winter now) that is very unpredicatable. I get punished if i happen to get some solar on a particular day. Why is it assumed that the algorithm can predict my requirements better than me?
    I know that once you set the time based control then it has to "learn" your system to react accordingly but it's very poor at doing that. VERY poor. I don't understand the apparent reluctance to allow us to explicitly define by how much the powerwall charges at night. It's my battery isn't it? I can predict my usage can't I? I can guess what the weather's going to be like can't I?
    I'm not saying turn off the algorithm, I'm just saying allow us to switch to manual control and hey, if i get it wrong and end up exporting electricity because i've charged up the PW too much overnight then that's my problem. And it's a preferable problem than not having enough juice in the PW in the first place.
    And don't get me started on the the PW discharging during my off-peak hours......geez. PW charing during off-peak then discharging during off-peak how stupid is that given the lossed incurred in charge and discharge. Dischage during off-peak should be a big no-no and yet it does.

    All this can be avoided by giving us a manual option. I was going to buy a second battery to help me in winter but i'm not going to now as the problem will be the same.It's pointless.

    I can't even see an excuse with respect to the app - they've already developed the sort of interface we'd need to use with the sliders etc so just give us a "charge up to" slider for off peak hours for goodness sake.

    But then again they're never going to read this are they.....all i can say is keep on putting those "feature requests" in through support and see if they'll listen. Or consider getting a battery system from another supplier. If i new this would be the case I woudl have thought a bit harder prior to my original purchase.

    Tesla, please let ME manage my energy storage and use rather than trying out this rubbish little AI on us.

  • edited November 2019

    Yep i get exactly the same sort of issue - wake up with mid-teens power stored in the PW when i'm getting a day of crap weather and no/little solar predicted. I once went to bed with 3% and woke up with 3%!!!???
    With respect to the app not displaying correctly although that is a crap excuse i have seen that quite a bit. On balance the app is correct most of the time but it certainly can be wrong. I've had it showing max drain on the battery when it thinks it's still supplying my heat pump when in fact my heat pump was off at the time after haivng run for a while. However, the stored power in the powerwall wasn't going down by the same extent if you know what i mean. So it was reporting the power drain, but the power drain wasn't actually happening.

    That make sense? I'm happy to forgive a lot of this to be honest but i just wish they'd allow us manual setting of the PW during off peak. It would make an almost great system, bloody great.
  • edited January 2020
    Agree with the points above - just a small amount of manual control would make a huge difference.

    Prompted to call support line as after a few days running in "self-consumption" mode due to sunny weather, switched back to 'Advanced Time of Use" with overnight charging....made the change at 2pm, next morning - no overnight charging. Called support - 12 minutes on hold then "ah yes the powerwall needs to learn your consumption habits that's why we recommend only changing modes a couple of times a year" - errr what, I just want the thing to change modes when I tell it to.....

    Rather underwhelmed to be honest Tesla.
  • edited January 2020
    Chris, Powerwalls are not allowed to charge from the grid with most utilities in the U.S. They can only be charged from a solar array, except for the Stormwatch function. Relax, your PWs will likely charge from excess solar the next day.
  • edited January 2020
    Gregbrew, with respect, we get that Powerwalls are (in the main) not allowed to charge from the grid in the US.

    The issue highlighted by me (ok i wasn't explicit i was also UK-based!) and certainly by others was that this was a UK issue, where grid charging is not only allowed but actuated incentivised by energy retailers through tariff design.

    So i'm very prepared to accept that the Powerwalls AI functions more effectively in areas where weather may be more consistent. Certainly in the UK in winter we don't have that - we can have a few days of great sunshine, then back to 100% overcast. Plus, the in-day forecast can often change. Benefits of a maritime rather than continental climate I guess.

    So in our case, we had a few days of great solar production, "Self Consumption" mode worked fine. Then back to the grey - nope, AI assuming the last few days of solar production was 100% wrong.

    The suggestion by Cankfarm upthread of a "charge up to a minimum of" option seems a great, straightforward option to me as a way of giving input to the AI : either due to changing weather or consumption (more load than usual expected, or return from holiday)

    Its an easy means of correcting a very fundamental flaw in the Powerwall, which is a great shame given all the creativity Tesla has harnessed in creating something that could be very easy for most of the population to adopt.
  • edited January 2020
    Sent another request to support!!!

    Algorithm failed to top up enough during off peak yesterday and i ended up with a flat battery half way through the day, unfortunately it didn't learn by it's mistake and it failed to top up again last night, it's now dull, grey and overcast here in the UK, it's 2pm in the afternoon and the battery is flat again with me now having to pay peak rate for over 10 hours before the algorithm gets another try..... but 3rd time lucky, come on you can do it! (i just need 80%).

    Tesla please give us manual control.
  • edited January 2020
    It's unlikely that you will ever get a response from Tesla via e-mail. That seems to be a pattern reported and repeated here.

    Call them. I've received fantastic customer support via the phone.
  • edited January 2020
    I am in the UK and my powerwall was delivered on the 6th June 2017. Dispite their advertising claiming that I could charge the powerwall during offpeak and use the stored energy during peak periods, it was many months before this was possible, I was informed by Tesla that I did not need manual controls to adjust offpeak charging as the system used local weather forecasts to calculate solar power generation and could therefore do this automatically. This might have been their vision but it was soon obvious that this was false. I have observed that if we have a moderately sunny day it will assume that the following day will be sunny and will continue this assumption for three days before putting any significant offpeak charge into the powerwall.
    I have had conversations with some senior Tesla managers in the UK / Europe requesting that we have a manual control to set the % offpeak level that the powerwall charges to or will not discharge below. I was informed 15 months ago that this was under consideration, but I have little hope that anything will be done. This has been suggested on other forums for some time, but everyone has been ignored.
    I did consider trying to sue them for false advertising but this would be expensive and probably take years, they are too large a company to have much chance of success.
    I am self sufficient on my household energy for seven months of the year, so the powerwall can be good, but this software problem leaves a bad taste, and it has cost them as I have been honest and told friends of the problem and they have decided not to buy.
  • edited January 2020
    Just purchased and installed (california). So I cannot charge the powerwalls at night from grid at super low rates?
    If I would have known that, I would not have purchased. Guess its my fault for not researching enough.

    This is going to cause my electric bill to go up!! I'll be charging the PW when I could be getting Peak Rate Credit by sending solar back to the grid
  • edited January 2020
    My big concern is if the guys that wrote the powerwall algorithm are now working on the SpaceX project. If they take some Powerwalls to Mars It wouldn’t surprise me if they make a new algorithm to control the whole thing, if the weather on Mars isn’t the same everyday they could end up with flat batteries and no life support.

    For me it just costs cash, but on Mars it could cost life’s!

    (At least they can make a film about it afterwards).
  • edited February 2020
    "Across the pond (USA), it's actually against the law to charge a Powerwall from the grid, except in weather emergencies via the Stormwatch function."

    That's not quite true. In the US, if you get the energy tax credit, your system qualifies only if it's restricted to charging from solar. In other words, if you never ask for the tax credit on your tax return, there's no federal restriction. If you get the tax credit, and then use the battery to charge itself off peak so you can get the energy back during peak but non-solar-generating hours, it would be tax fraud. It's a gray area how long the restriction would last. If you get a tax credit for solar, there's nothing stopping you from disconnecting your solar system a year later, so it's hard to say whether, if you complied for the tax year in which you took the credit, the government could force you to comply in other tax years. The IRS would have no way of knowing of course. But most people wouldn't want to give up a credit of almost 30%, which can be taken over a number of years for those with lower incomes, since they might not make the money back, especially if they have an adequately sized solar array. I wouldn't want to be the guy who challenged the IRS in tax court, but it would be hard for them to claim anything not having to do with a current return, and they can't audit you for something from over three years earlier that wasn't fraudulent at the time that you filed. If they aren't disputing something on a current return, I don't know what they could even take to court.

    "US utilities won't allow you to charge PWs from the grid...even in "Backup" mode. PWs can only be recharged from PV."

    That too would depend. My utility is PG&E and that means that I get an SGIP rebate. I'd be ineligible if I did have a system that charged itself from the grid. I can use power off peak and store it, such as by charging my cars overnight. But I can't charge a Powerwall overnight from the grid. In theory, if I didn't apply for the SGIP rebate, I'd have the right to use electricity for anything I wanted. They couldn't tell me that electricity that I pay for couldn't go into a particular battery. But I'd be foolish to give up thousands of dollars in order to have the option to do something that wouldn't make up for it.

    My rate plan is for EVs, and was in place from before I had solar. With Solar, I did have new agreements so a few terms changed, but the battery is something different. The agreement goes with the SGIP, and I could have, in theory, added a battery with no solar and no SGIP agreement, in which case, charging from the grid would have been fine. Merely getting a battery might not be enough to impose a restriction, depending on the utility, but if you had any sort of agreement, especially if there's any sort of rebate, you can bet that the power company had a restriction that helped them offload things from their grid. Again, it's extremely likely that you would have the restriction with any utility, and in particular because not agreeing to it would cost a lot more money.

    With PG&E and the SGIP program, I'd need approximately 16% of the capacity to be cycled per day on average, and less than that would be a violation of the agreement. In real life, it's more cost effective to use more.
  • edited February 2020
    Please describe the method whereby I can charge my PWs from the grid at night.
  • edited February 2020
    UK poster. completely agree about the algorithm. Friday night before Storm Ciara hit the PW charged to 18%. The Saturday was just about dark. I'm using time of use to charge on off-peak to use at peak times. It does seem random as to how much it charges up. It clearly isn't driven by the forecast for the local area. A manual over-ride would be brilliant. It really can't be hard to do. Come on Tesla, you appear to have developed a driver less car, but can't charge a Powerwall according to a users requirements.
  • edited February 2020
    We run our PW in backup mode, 100% allocation, and turn off the grid with a breaker. Usually, we get enough sun to charge the PW full by midday or so, then the house runs on the PV's until sundown, when the PW takes over. It has enough to get us through evening, night time, and into the morning when there's still 40-50% battery left, we can make coffee and toast and watch TV, and PW starts recharging from the PV's around 9am. If there's no sun, we can switch on the grid breaker, it takes about 5-6 minutes for the gate to recognize that the grid is there, at which point it will run the house and recharge the battery from the grid, drawing about 4 Kw, which will charge the battery up quickly, then we shut off the grid and go back to the battery. It does charge correctly and you can see all this action on the app
Sign In or Register to comment.