Powerwall 2 using grid power in Time Based Control mode

[WillC]

I have a two week old Powerwall 2 running in time based control. The electric rates are all entered correctly with clearly defined peak & off-peak rates. However, when its peak times the battery is sitting in standby allowing power draw from the grid. The battery is charging fine overnight during off-peak and charging with excess solar in the day. Then early morning and evenings when I want the battery to discharge its allowing too much draw from the grid. The battery is providing some power but most seems to come from the grid. The total house load is around 2-3 kw so its not like the battery is maxing out. Any ideas?

 

[Moded3]

Same issue with me. I've had mine for nearly 3 yrs now. I was on Time-Based control prior to mid-Feb when things change, perhaps related to a SW update? It used to do what was programmed to do, use grid during off-peak, use panels/batteries during peak. after mid feb(SW update?), there is now spikes early and late of peak and off peak period. I'd be interested if someone actually have a good explanation if someone with similar experience/knowledge with this behavior...

 

[dailo]

You may want to play around with the buy and sell prices. I have my sell prices set a few cents lower and TOU will try to optimize using solar to charge the battery and offset house usage automatically. It isn’t perfect, but has gotten a lot better. If there isn’t a large delta between peak and off peak, it also may not think it is worth using PW since won’t save much in cost.

 

[xWren]

@WillC welcome to the wonders of the Tesla algorithms which in the 3 years I have had a Powerwall, and whatever version of the firmware (which may or may not have some kind of weather based solar prediction), is simply unable to cope with the daily variation in UK weather. Today's weather and thus my generation can vary by 15kWh from what happened yesterday, and Time-Based control will do the wrong thing.

Some people have convinced themselves it works with an adjustment in the deltas in peak and off peak prices, others that it now looks at local weather predictions too (honestly I don't believe it). I got so frustrated with the random misbehaviour I no longer use Time-Based control at all, instead setting the reserve percentage at the start/end of my peak period using API calls from cron job on a RaspberryPi based on my judgement of the weather and my expected use. The only problems I have are when the Tesla servers or internet connection are down and so we can't control our Powerwalls at all.

Love my Powerwall, detest the badly designed software that Tesla created to run it.

 

[WillC]

After speaking to my PW installer their advise was to leave in Time-Based mode and let the algorithm do its job, and to be fair its actually got a lot better. The problem I found with self-powered mode was the midnight EV charging that would allow the battery to drain unless you manually change the battery reserve. So for me, it looks like TBC will be the way forward even if its not perfect all the time. There is always a small amount of grid draw and some annoying moments you glance at the IHD and see the grid is drawing 2-3 Kw while cooking, but then the battery kicks in and seems to work again. What I don't understand is why the battery goes into a standby mode at all. If the electric rates in TBC indicate its not economical to draw from the grid why does it!

 

[Bill.O]

I stumbled upon this thread while troubleshooting a similar issue with time-based control on my Powerwall 2.

Here's a workaround that helped me align the Powerwall operations with my preferences (those preferences being to only use grid power as a last resort/top up the battery when cheap and necessary):

1. Set the off-peak hours accurately (2am to 5am in my case).
2. Designate all other hours as peak.
3. Set all export/sell prices to £0.00.

This setup tricks the Powerwall into charging during off-peak hours, while providing power to the house during the rest, considering the high (peak) utility costs. Additionally, setting export/sell prices to zero encourages the system to store excess solar energy, rather than exporting it during peak hours. This arrangement has bridged the functionality between time-based and self-powered modes effectively. It also benefits from the solar forecast, as it knows to skip charging from the grid if it expects lots of solar generation the next day(s). You do lose out on the 'Impact' section in the app being accurate, but that seems trivial to me.

Hope this alternative approach aids others facing similar issues!

 

[Simon Thompson]

Hi all,

I have fiddled with the settings for time based control and my powerwall resolutely insists on charging from the grid at peak times even when it has backup power.

So, I have used my computer cleverness and all the helpful opensource code out on github to set up instructions to move the reserve to 100% for off peak hours and this forces the thing to charge. Once the off peak electricity is over I have an automated call that sets reserve back to 20% to allow for discharging. I am in self powered for this to work.

However, max charge from the grid seems to be 1.2kwh. I have 4 hrs of off peak electricity which means I get 4.8kwh. This is not what I want!

Does anyone know why it won't charge at 5kwh like it's supposed to be able to?

 

[scdoubleu]

I have fiddled with the settings for time based control and my powerwall resolutely insists on charging from the grid at peak times even when it has backup power.

Can you post a screenshot of your "Utility Rate Plan" page from the Tesla App? Here's mine for Octopus Intelligent for import, and Octopus Outgoing for export:

If you don't have an export (SEG) tariff, set the sell prices to zero.

So, I have used my computer cleverness and all the helpful opensource code out on github to set up instructions to move the reserve to 100% for off peak hours and this forces the thing to charge. Once the off peak electricity is over I have an automated call that sets reserve back to 20% to allow for discharging. I am in self powered for this to work.

However, max charge from the grid seems to be 1.2kwh. I have 4 hrs of off peak electricity which means I get 4.8kwh. This is not what I want!

That's normal behaviour when using standby reserve to force a charge.

 

[Simon Thompson]

As requested - image below.

BTW. thank you very much for engaging.

My concern with Octopus Intelligent was the car charging and car registration - my Zappi charger isn't connected to the internet. So will Oct Int work for me.

If yes then the extra 2 hrs of off peak would be a good addition to the 4.8kwh of cheap grid electricity I can harvest already.

That's normal behaviour when using standby reserve to force a charge.

Hmm that's tedious - so it will only charge fast when it has time based control...

 

[scdoubleu]

As requested - image below.

All looks normal, so definitely odd that it should be pulling from the grid during peak. You should raise this issue with support by emailing [email protected].

My concern with Octopus Intelligent was the car charging and car registration - my Zappi charger isn't connected to the internet. So will Oct Int work for me.

If yes then the extra 2 hrs of off peak would be a good addition to the 4.8kwh of cheap grid electricity I can harvest already.

This is a valid concern - any IO slots outside of the off-peak hours will charge the car from the Powerwall. There are HomeAssistant automations to force the Powerwall standby reserve to 100% in this situation. Pretty sure there are posts in TMC's UK and Ireland section which document the work-arounds.

 

[Simon Thompson]

All looks normal, so definitely odd that it should be pulling from the grid during peak. You should raise this issue with support by emailing [email protected].


This is a valid concern - any IO slots outside of the off-peak hours will charge the car from the Powerwall. There are HomeAssistant automations to force the Powerwall standby reserve to 100% in this situation. Pretty sure there are posts in TMC's UK and Ireland section which document the work-arounds.

thank you.

BTW I use GCP (pub/sub) and cloud functions to run charge-tesla.py. Using GCP like this is free, and appears to consume milli-watts per day. I need to think about setting up a HTTP responsive cloud-fuction to auto upload the API key but basically pasted it in a local config file for now.

 

[xWren]

I have fiddled with the settings for time based control and my powerwall resolutely insists on charging from the grid at peak times even when it has backup power.

So, I have used my computer cleverness and all the helpful opensource code out on github to set up instructions to move the reserve to 100% for off peak hours and this forces the thing to charge. Once the off peak electricity is over I have an automated call that sets reserve back to 20% to allow for discharging. I am in self powered for this to work.

However, max charge from the grid seems to be 1.2kwh. I have 4 hrs of off peak electricity which means I get 4.8kwh. This is not what I want!

Does anyone know why it won't charge at 5kwh like it's supposed to be able to?

Yes the max charge rate is only available in autonomous mode, with self-powered charging at half that rate. I even raised a ticket with Tesla and was told it would be changed in a firmware update in 2022, still awaiting that miracle.

Having had the same frustration at the automated Powerwall behaviour (designed for locations where weather and use are consistent patterns), I also used my computer cleverness and Github to produce scripts that I run on a RPi that change both backup reserve percentage and operation mode to control the charging/discharging behaviour.

If slower charging will be sufficient I stay in self-powered mode and just set the backup reserve percentage, but deeper into winter I also set it into autonomous mode during my cheaper electricity period and the back to self-powered when I lower the backup reserve percentage again.

Just had to edit my scripts since the Tesla API changed last night and api/1/powerwalls/ endpoints no longer work, now it is set as default_real_mode and backup_reserve_percent in energy_sites data.

 

[Simon Thompson]

Yes the max charge rate is only available in autonomous mode, with self-powered charging at half that rate. I even raised a ticket with Tesla and was told it would be changed in a firmware update in 2022, still awaiting that miracle.

Having had the same frustration at the automated Powerwall behaviour (designed for locations where weather and use are consistent patterns), I also used my computer cleverness and Github to produce scripts that I run on a RPi that change both backup reserve percentage and operation mode to control the charging/discharging behaviour.

If slower charging will be sufficient I stay in self-powered mode and just set the backup reserve percentage, but deeper into winter I also set it into autonomous mode during my cheaper electricity period and the back to self-powered when I lower the backup reserve percentage again.

Just had to edit my scripts since the Tesla API changed last night and api/1/powerwalls/ endpoints no longer work, now it is set as default_real_mode and backup_reserve_percent in energy_sites data.

Ah ha! - so just change the mode to autonomous at 12:30am and hopefully moar charge?

 

[Simon Thompson]

Could you share the json for the default_real_mode command?

 

[xWren]

Could you share the json for the default_real_mode command?

I make extensive use of Tim Dorssers open source work on Github TeslaPy and this could be of specific help No longer able to set Powerwall to self_consumption mode · Issue #136 · tdorssers/TeslaPy The sort answer is the JSON endpoint to set mode is "api/1/energy_sites/{site_id}/operation" and to get it "api/1/energy_sites/{site_id}/site_info" and the field in the response data is "default_real_mode"

 

[Simon Thompson]

For anyone finding this thread it's worth getting tesla technical support to look at how your installation is responding. They were very helpful in determining that there is an issue with the CT Clamp configuration on my installation which is preventing the loads being understood and therefore preventing the powerwall self adaptation working correctly.

 

[EdSt]

I find the monthly electric bill went down the most when using Time Of Use settings that had the Powerwalls charge fully at super off peak times, cover the house usage during peak times as much as possible.

 

[Radlaw]

Do these recommendations work if you have solar panels, or does the solar generation override?