Time-Based Control?

[miimura]

I'm having Powerwall 2.0 + backup gateway + solar installed in January. My distributor limits exports to 5kW but I'm having 13kW PV installed (10kW of inverter capacity)

This means that in addition to "inverter clipping", I will have "export clipping" where (self consumption + 5kw export) is less than PV generated:

For this reason, I want to delay the charging of Powerwall 2.0 until ~10am. This means all early to mid-morning generation is self-consumed or exported. Around the time "export clipped" power should start to be available, I want to start charging the Powerwall.

I have a single tariff and never want to charge battery with grid power. I anticipate that I will be discharging the battery down to reserve level every night due to self-consumption.

I think the configuration I need is something like:

TBC (Balanced)
9pm - 10am Peak
10am - 9pm Offpeak

If I'm reading the thread and Modes of Operation correctly, this should:

- Never charge the powerwall during peak time (even when "excess solar" is available?)
- Begin charging with excess solar at 10am (possibly "any solar" if the Powerwall thinks it will need to?)
- All evening/night consumption will be offset by the Powerwall until it hits reserve power.

Does this sound correct?

By default, the Powerwalls will always charge from available solar. I can't think of a way to use the currently available settings to stop that.

The more fundamental question I have is about your electric distributor - how do they enforce 5kW export limit if they allow larger solar systems to be installed? It seems that there has to be some way to configure the solar inverters to self-curtail to meet this requirement. If that is possible, then you would just run in Self-Powered Model on the Powerwalls and let the solar clip after the batteries are full.

The only other solution I can think of is to interfere with the Powerwall's data collection to hide the solar production in the morning so that it is exported.

 

[liplus]

Disappointing. If that's the case, then their "Modes of operation" document is flat-out wrong:
Powerwall Modes of Operation with Solar

If it's going to charge the battery using excess solar in peak times, it should say so:

 

[miimura]

In my experience, the one you added in red, Charging from "Excess Solar (Peak)" will never happen. During Peak hours the Powerwalls will discharge to cover "Any Usage" and the solar will be exported.

I think what people without net metering really want is a way to run Self-Powered, but selectively block Powerwall discharge during certain hours. As far as I can tell, Time Based Control cannot be configured to do that. The only way I can think of to accomplish this is to arrange your circuits and your CTs such that the system is not aware of the usage that you want to exclude. However, that is not an easy thing to do in most cases.

 

[PBBear]

I think the configuration I need is something like:

TBC (Balanced)
9pm - 10am Peak
10am - 9pm Offpeak

If I'm reading the thread and Modes of Operation correctly, this should:

- Never charge the powerwall during peak time (even when "excess solar" is available?)
- Begin charging with excess solar at 10am (possibly "any solar" if the Powerwall thinks it will need to?)
- All evening/night consumption will be offset by the Powerwall until it hits reserve power.

Does this sound correct?

It is certainly plausible. The Tesla TBC app has no idea of actual tariffs,and seems to assume US-style net-metering where FIT equals consumption price. It would make financial sense therefore during peak times for the system to export ALL solar to the grid (to maximise feed-in revenue at the peak rate tariff) and serve the load from the battery - until the battery gets down to the reserve level.

However, thats not what mine does.

I'm using TBC (Cost Saving) not TBC (Balanced), but the same behaviour will probably apply.
During all peak, shoulder and off-peak times, if there is any empty room in the battery, any excess solar is poured into the battery until the battery is full, and then excess solar starts being directed out to the grid. The house load is always served from the solar if there is any solar being generated. The only real impact of TBC control I've seen is to stop the system discharging from battery after 10pm when off-peak starts, reserving the charge until the following morning while running from grid overnight.

I'm in Australia also, where the US-style equal-FIT net metering doesn't apply, so perhaps Tesla have programmed different behaviour for the Aussie market, as the behaviour mine does under TBC is probably the behaviour most people would intuitively want to happen I think, given the way our very low Feed In Tariffs work.

(see WillisAve 7.370kW | Live Output for my system operating under TBC (Cost Saving) - esp the 'extended data' tab, and scroll back a few days).

 

[ybbor]

I just had my Solar System and two Powerwall2's installed yesterday. I just got them added to my account, and I don't have "Time-Based Control" as an option in my app. Only "backup-only" and "self-powered". Firmware 1.34.3.

Do I need to do anything to get that option?

Also, when doing the registration, there is an optional checkbox called "GRID SERVICES". What is that? I did not check it.

 

[bmah]

I just had my Solar System and two Powerwall2's installed yesterday. I just got them added to my account, and I don't have "Time-Based Control" as an option in my app. Only "backup-only" and "self-powered". Firmware 1.34.3.

Do I need to do anything to get that option?

Mine showed up after a day or two, automatically as far as I recall. Installed a couple months ago.

Bruce.

 

[ybbor]

Mine showed up after a day or two, automatically as far as I recall. Installed a couple months ago.

Bruce.

Thanks Bruce! I'll keep an eye on it over the next week.

 

[Ulmo]

Also, when doing the registration, there is an optional checkbox called "GRID SERVICES". What is that? I did not check it.

Can you please tell me what "doing the registration" looks like? Did you get instructions? Who sent them to you? What do the instructions say?

I don't think I went through the same process when mine were installed, so I'm asking, so I know what the current access to features looks like, so that I can attempt to re-register mine to get the additional settings.

 

[Musterion]

Can you please tell me what "doing the registration" looks like? Did you get instructions? Who sent them to you? What do the instructions say?

I don't think I went through the same process when mine were installed, so I'm asking, so I know what the current access to features looks like, so that I can attempt to re-register mine to get the additional settings.

@Ulmo I think that @ybbor is referring to the Powerwall self-registration available here: Powerwall Self Registration | Tesla
Did they ask you to fill that out during or after installation?

There is a checkbox for “Grid Services” there, which I believe gives you opt-in ability to various grid-interactive programs that utilities may offer that give you small incentives:

 

[Mark77a]

Hey Guys
Just got PW2 with backup gateway (after 3year wait, in UK) .

Question why does it take grid power to charge itself when there is excess solar energy, and the PW charge level is well over the 10% I set for backup reserve. ?

This is with customize/'advanced'/cost saving (with grid peaks added). It does same when set to 'self Powered' . 10% backup reserve, 30+% SOC.

I'm tempted to manually cut the grid to prevent this. Ps This is early morning and once the sun is up the pV's give out 3-4 kW

 

[JohnRatsey]

How many days has your PW been in operation? Tesla support would probably say that you need to give it more time to learn your usage and generation patterns (although, as I have pointed out to them on several occasions, Britain isn't California and yesterday's weather is not a good guide to what will happen today).

If, within a few days, your PW shows no sign of more efficient behaviour then you will have to complain to Tesla support ([email protected]) and ask for better user control over the battery's charging behaviour. Join the queue!

 

[Quigglyy]

Hiya, Am in the UK and just had a PW2 set up yesterday. Currently in customise only have self powered as an option. Does it take a period of time, and how long, until I can start to use off-peak time-based control charging overnight?

Cheers

 

[Oppenheimer]

Finally got my powerwalls working properly after some misplaced TCs by the installer. Everything works great, except, for situations where the PW decides to offload leftover solar to the grid without the battery being fully charged. It'll do this during cost savings peak, which is insane, since in California, PG&E charges 4 times the amount for using electricity than providing it back. It's a financially bad decision to output *anything* to the grid here when the battery is not yet full.

Anyway, I'm going to be running some experiments here and editing the post as I find out new information since the time based control clearly has some weird edge cases.

This is today during peak hours while I was generating more solar than I was using. The excess solar is going towards the grid instead of charging the not yet full battery, AND to make matters worse the powerwall is discharging.


This is the desirable state in any situation where the battery is not yet full. I hate to not be a good Samaritan here, but until I can get a chance to upgrade our solar system, I need to keep *any* charge that solar generates that I have room to store. This is in Self-Powered mode, where solar energy is going towards the house and charging the battery. (Perfect)

 

[power.saver]

Actually, that how it's supposed to work. In TBC cost savings, the PW will send ALL solar to the grid during the peak, and power your house from the PW. If you don't want that, then switch to self consumption mode. Where I am, I get $0.51 per kWh in the peak, so I want to send all solar to the grid during that time and draw nothing from the grid.

 

[miimura]

This is today during peak hours while I was generating more solar than I was using. The excess solar is going towards the grid instead of charging the not yet full battery, AND to make matters worse the powerwall is discharging.

This is maximizing your NEM credits. It's called arbitrage. You are using power generated during Off-Peak or Part-Peak to power your house during Peak when the power is more expensive. You are also earning the maximum value of your solar at the same time. This is the essence of the Cost Saving mode.

If you want to be mad about something, be mad when it discharges during Off-Peak when it was charged from Part-Peak. Then it's just wasting battery cycles and giving up NEM credit value.

 

[ohmman]

It is definitely what you want. With NEM, you'll be credited the current TOU rate when you're feeding the grid. My Powerwalls ensure that all of my solar exports to the grid when rates are at peak. Sell high, buy low.

 

[Darwin]

In TBC cost savings, the PW will send ALL solar to the grid during the peak, and power your house from the PW.

One caveat to this. That is true for TBC cost saving when in a peak period. TBC cost saving in a shoulder period (not peak or off-peak) behaves similarly to self-consumption.

 

[Quigglyy]

So, the advanced TBC settings appeared which is great, but opens up more questions!

I have an overnight off peak rate and want the PW to charge from the grid to full, the discharge in the morning until solar kicks in and then can recharge the battery, to be used in the evening period. Any time other than the overnight off peak is fixed rate. The return on power back to the grid is paid at 1/3 of the consumption cost so it's not effective to feed back excess solar if the battery isn't at 100%

Can anyone possibly advise as to the most effective setup please, and I hope that this is a possible setup!. Would be appreciated v muchly!

I was reading that having off peak 00:00 - 5.00 then peak everything else prob isn't ideal, should I just have off-peak and shoulder everything else?

Thanks in advance for the advice!

 

[Quigglyy]

No backup set on my gateway btw

 

[ohmman]

So, the advanced TBC settings appeared which is great, but opens up more questions!

I have an overnight off peak rate and want the PW to charge from the grid to full, the discharge in the morning until solar kicks in and then can recharge the battery, to be used in the evening period. Any time other than the overnight off peak is fixed rate. The return on power back to the grid is paid at 1/3 of the consumption cost so it's not effective to feed back excess solar if the battery isn't at 100%

Can anyone possibly advise as to the most effective setup please, and I hope that this is a possible setup!. Would be appreciated v muchly!

I was reading that having off peak 00:00 - 5.00 then peak everything else prob isn't ideal, should I just have off-peak and shoulder everything else?

Thanks in advance for the advice!

In the USA, if you've got a NEM connected system, you cannot charge the PWs from the grid. You can only charge them from solar. The way it works at my house is that I charge them up in the mornings on part-peak on PG&E's EV-A rate plan. That will change in November, as off-peak extends through 3pm. Then, when peak rates hit, I begin selling all of my solar back to the grid and using only the PWs to run the home.

I'm unsure if the rules differ in the UK, where you appear to be located.