Time-Based Control?

[Oppenheimer]

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.

I haven't found this to be the case. I set up no peak but only part-peak and it behaved by sending excess solar to the grid instead of charging my Powerwall. I'm currently managing this manually, but I'd really like to schedule it.

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.

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.

Where are you guys located? In the Bay Area California, PG&E costs 51 cents per kw/h during peak, and only pays back 22.4 cents per kw/h. It's definitely not equal, which is why it's frustrating the way my solar outputs to the grid instead of charges (when not full) during peak and part-peak hours.

 

[miimura]

Where are you guys located? In the Bay Area California, PG&E costs 51 cents per kw/h during peak, and only pays back 22.4 cents per kw/h. It's definitely not equal, which is why it's frustrating the way my solar outputs to the grid instead of charges (when not full) during peak and part-peak hours.

PG&E does straight net metering. If you export more kWh than you consume during the Peak hours, you will absolutely get a credit at 51 cents per kWh. However, with the EV Peak rate going to 9pm, it's much harder to have a Peak surplus than it used to be unless you have batteries.

 

[ohmman]

In the Bay Area California, PG&E costs 51 cents per kw/h during peak, and only pays back 22.4 cents per kw/h.

I'm on PG&E in the Bay Area. They pay back 51 cents. Where do you see that they only pay you 22.4c/kWh?

 

[Oppenheimer]

PG&E does straight net metering. If you export more kWh than you consume during the Peak hours, you will absolutely get a credit at 51 cents per kWh. However, with the EV Peak rate going to 9pm, it's much harder to have a Peak surplus than it used to be unless you have batteries.

I'm on PG&E in the Bay Area. They pay back 51 cents. Where do you see that they only pay you 22.4c/kWh?

Mine definitely doesn't according to their energy cost estimates on the PG&E site. I'm currently on EV-A not TOU which may affect this. Also, I had trouble finding the day I got 22 cents, so here's one where PG&E charged 51 cents, to provide power, and 28 cents to take it back.

Here's the charging rates:

And here's the generation rates:

 

[miimura]

EV-A Peak period is 2-9pm. The Generation box you showed is during the Part-Peak rate period.

 

[Oppenheimer]

EV-A Peak period is 2-9pm. The Generation box you showed is during the Part-Peak rate period.

Holy *sugar*, you're right. Why did I think it was 1PM all this time, better part of a year... Having some serious mandela effect right now. K, no problem anymore.

 

[Solar1920]

Just curious, if you guys in the USA can’t draw from the grid, not all the states in the US can be gifted with California type weather, some must be more similar to the UK and have a longish dark unpredictable winter and some maybe long periods of snow, do you just up your reserve to stop the powerwall sitting at zero for days (or weeks) and wait it out? if your on a TOU rate you must take a hit on your peak periods.

 

[MarkJ]

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!

I'm in same situation in UK so just do what you thought with peak during the night and everything else off peak. Use TOU cost saving. The only thing that is a bit suboptimal is the PW decides how much to charge overnight based on previous use & solar so the battery may be too full or too empty. Tesla are aware of this and will probably add either more control or a manual mode.

 

[ohmman]

Just curious, if you guys in the USA can’t draw from the grid, not all the states in the US can be gifted with California type weather, some must be more similar to the UK and have a longish dark unpredictable winter and some maybe long periods of snow, do you just up your reserve to stop the powerwall sitting at zero for days (or weeks) and wait it out? if your on a TOU rate you must take a hit on your peak periods.

I'm in Northern California. Don't forget that we have winter here as well, and it's not terribly far from a Scottish spring. Wet, cool, and dark. As you say, I just increase my reserve in the winter and know that I cannot take as much advantage of the arbitrage opportunity.

 

[Quigglyy]

I'm in same situation in UK so just do what you thought with peak during the night and everything else off peak. Use TOU cost saving. The only thing that is a bit suboptimal is the PW decides how much to charge overnight based on previous use & solar so the battery may be too full or too empty. Tesla are aware of this and will probably add either more control or a manual mode.

Thanks! Do you mean off peak at night and everything else peak, or the grey ‘shoulder’ period?

We have an electric aga that will use a complete charge by 9am...!

Cheers!

 

[JohnRatsey]

Thanks! Do you mean off peak at night and everything else peak, or the grey ‘shoulder’ period?

We have an electric aga that will use a complete charge by 9am...!

Cheers!

If you define your off-peak period then the battery may decide that it's appropriate to charge during that period (as already noted there's currently no user control over how much to charge - Tesla's algorithm considers usage and solar generation over the previous 2 or 3 days and has no solar forecast input). I've not tried defining a shoulder period but suggest you try it to see if it meets your needs.

 

[Vostok]

Bumping an interesting discussion...

I’ve had PW2 for over 6 months now and have operated it on self-consumption mode since inception. I’ve only just started to play with TBC.

My ideal of how I’d like PW2 to work is:

1. PW2 should operate in self-consumption mode at all times except off-peak;
2. PW2 should never discharge during off-peak times (typically we charge our cars during off-peak using cheap grid power, we don’t want the PW2 to do that); and
3. If allowed in your market, there should be an option for PW2 to charge to 100% from the grid during off-peak times. This would maximise solar excess during the day (hence FIT income) since you’d start the day with a full battery rather than one that is empty or near empty.

My limited experience with TBC-Balanced is it does very weird things and does not operate at all how I expect.

My experience with TBC-Cost Saving is better, and seems be to closer to my ideal. But even then, it doesn’t seem to fill the battery even when it could. Today for example, during grid “shoulder” period, my PW2 reached 75% and went into standby, with solar excess going to the grid. But as soon as the peak period started, the battery started filling again, but it probably won’t get to 100%.

Both TBC modes seem operate like “black boxes” and it’s not clear or obvious what the algorithms are trying to do.

I’m wondering if only setting off-peak and peak periods in the App (no shoulder periods) would have the desired effect in TBC-Cost Saving?

Or is a totally new mode of TBC required?

 

[miimura]

I don't know if it's this thread or elsewhere, but I've said before that there should be a "Scheduled Self-Powered" mode. This sounds like what you need. Basically, discharging is blocked during Off-Peak and any generation should go to charging. Everything else is Self-Powered. There has also been requests in this forum for "Advanced Mode" where the user could set up their own rules and configure things like multiple Peak periods per day. There is no evidence of any of this on the Powerwall roadmap due to Tesla's "excellent" customer communication. [/sarc].

Since I'm in USA and took the tax credit, I have to charge from 100% solar. Therefore, I haven't put much thought into grid charging algorithms. The UK customers have definitely put some thought into it. Most of them seem to want weather forecast based grid charging instead of the generation history based charging that they have now.

 

[power.saver]

I’m wondering if only setting off-peak and peak periods in the App (no shoulder periods) would have the desired effect in TBC-Cost Saving?

Yes, eliminating the shoulder will make it work like you desire. It will never discharge in off-peak, and will always discharge in peak. That is how I have mine configured.

 

[eml2]

Yes, eliminating the shoulder will make it work like you desire. It will never discharge in off-peak, and will always discharge in peak. That is how I have mine configured.

I also find that using just peak/off-peak in Balanced mode is the closest thing to "Scheduled Self-Powered" mode. However, at least for me, it may still discharge at the end off-peak before the sunrise if it thinks it has too much energy stored. To prevent that, I change the reserve % just a bit below SoC the night before so that it will only discharge a little in off-peak if it comes to that.

 

[d21mike]

Yes, eliminating the shoulder will make it work like you desire. It will never discharge in off-peak, and will always discharge in peak. That is how I have mine configured.

Does not work for me. And read the "However" in the post that follows yours. My goal was to have a setting that "eliminates" discharge from anytime except sundown (about 5pm) until about 10pm. For now I just set my reserve to 70% and use Self-Powered mode. My usage during the Winter PEAK is around 30% of my batteries most of the time. Summer when AC is on will be different and I will need to adjust the reserve. Scheduled Self-Powered would allow me to "exclude" my "Super Off Peak" hours from discharge and make it easier to discharge during shoulder if I wanted and also not have to have a 70% setting adjustment just to solve this problem. Also, it would work in Winter and Summer.

 

[Vostok]

Yes, eliminating the shoulder will make it work like you desire. It will never discharge in off-peak, and will always discharge in peak. That is how I have mine configured.

I’ll try that, although as subsequent posters indicated, PW2 behaviour does not seem entirely predictable and what it does seems to depend on your historical power usage profile, the state of charge before it enters various tariff time periods, and what charge state it thinks it will exit with.

I haven’t removed the shoulder tariff yet. Last night, battery was used to supplement grid draw for the house during the shoulder period, and that stopped as soon as off-peak started (10pm) and I was running 100% on grid. Cars charged from midnight but they didn’t need much and were done by 00:45. But then at 01:00 battery supplementation of the grid restarted, and from 02:30 to 07:00 (end of off-peak) the battery fully ran the house (background power draw, fridge, dishwasher). PW2 had about 35% charge at the end of off-peak (reserve set to 10%) and is now charging up again.

“Go figure”. PW2 is trying to do something smart, but only if I knew what that was.

 

[miimura]

PW2 is trying to do something smart, but only if I knew what that was.

This is exactly how I feel. It's trying to be smart, but there is no clearly documentable logic. Some of us just want hard and fast rules. One thing that could help it work in a smarter way is to have the user input $/kWh prices for consuming from and feeding into the grid. At least then it would know the magnitude of its actions instead of the general character of them.

 

[Vostok]

This is exactly how I feel. It's trying to be smart, but there is no clearly documentable logic. Some of us just want hard and fast rules. One thing that could help it work in a smarter way is to have the user input $/kWh prices for consuming from and feeding into the grid. At least then it would know the magnitude of its actions instead of the general character of them.

Yep.

I would have thought the price relativities between peak, shoulder, off-peak, and feed-in tariff would be critical inputs to any optmisation algorithm. Simply knowing when these occur is not enough. In my case, for example, my feed in tariff is higher than the price of off-peak grid electricity. That opens up arbitrage options - I can buy power from the grid and sell it back to them later at a higher price. But PW2 has no idea that is the case. Also, how much more expensive peak is compared to off-peak (in my case, 3.7x) is rather important in working out how much one should use PW2 during off-peak compared to grid draw the entire time.

 

[dweick]

Yep.

I would have thought the price relativities between peak, shoulder, off-peak, and feed-in tariff would be critical inputs to any optmisation algorithm. Simply knowing when these occur is not enough. In my case, for example, my feed in tariff is higher than the price of off-peak grid electricity. That opens up arbitrage options - I can buy power from the grid and sell it back to them later at a higher price. But PW2 has no idea that is the case. Also, how much more expensive peak is compared to off-peak (in my case, 3.7x) is rather important in working out how much one should use PW2 during off-peak compared to grid draw the entire time.

It does seem simple to me, given a rate plan optimize for savings. In my case the only time I would want to charge the PW from solar is if the grid is down and my solar output is greater than my home consumption, I get paid more for my solar production fed back to the grid than it costs to get power from the grid. I want all solar to go to the grid, I want no peak power from the grid, I want the PW to charge from the grid off-peak and discharge to my home on-peak. Simple enough but maybe we just need to wait for Gen3 or Tesla to make the PW a priority

Even my Tesla car doesn't honor scheduled charging completely, it is set to start charging at 3am and if I come home at 6pm and plug in it starts drawing some power from my Wall Connector to do something, maybe cooling the battery, who knows, but I simply don't want that. Demand charges are very high, how hard is it to have the software simply not draw power at peak times?