Time-Based Control?

[arnolddeleon]

Prior post with initial reactions to TBC Cost Saving mode are in Post #46. You're the second person to suggest altering the rate schedule to modify the behavior. I'm not going to do that. I'm going to see what it does over the next couple sunny days and then maybe try the Balanced setting to see if that matches my expectations better than Cost Saving.

I would be satisfied with the implementation of two simple rules with the rest of the time being Self Powered.
1. Do not discharge from battery during Off-Peak.
2. Power the home from battery during Peak.

That's it. It's not that hard. What exactly is "learning for a month" going to gain beyond those two simple rules?

What do you want it to do during partial peak?

I guessing the learning is figuring out how much load versus solar you have so it can predict how energy to discharge when. For example if the battery was charged off-peak, it would be ok to discharge during partial peak *if* there would be enough energy to cover the peak usage otherwise it should hold on the energy until peak. OTOH you would make sense to discharge during partial peak if there was more than enough energy to cover the peak. It also never makes sense to charge partial peak and to discharge it back out also during partial peak. However if the battery doesn't have enough energy for peak then it might make sense to top it off with partial peak power.

My simple scenario is:
1. Take all the solar during off peak
2. Top off during partial peak with excess solar if available and battery is not not full.
3. Discharge everything during peak (independent of load) hours.

Yes, this assumes you are allowed to sell battery to the grid. If (which is a big *IF*) TOU times and rates were set properly this would make the most sense for grid and the consumer.

arnold

 

[miimura]

What do you want it to do during partial peak?

Default Self-Powered behavior is fine during Part-Peak. Basically that means keep the grid at zero as much as possible. When above the Reserve, power the home from battery if solar is insufficient and charge from surplus solar. Below the Reserve, let the grid power the home and put all the solar into the battery.

Today, my Powerwalls were in Standby from Midnight until 2pm. They went back into Standby when they hit the 50% Reserve at 8:40pm. Clearly this cannot continue. Last week when it was rainy, it did not charge much. I'm interested to see what it does tomorrow starting from the Reserve SOC on a sunny day.

 

[arnolddeleon]

Default Self-Powered behavior is fine during Part-Peak. Basically that means keep the grid at zero as much as possible. When above the Reserve, power the home from battery if solar is insufficient and charge from surplus solar. Below the Reserve, let the grid power the home and put all the solar into the battery.

Today, my Powerwalls were in Standby from Midnight until 2pm. They went back into Standby when they hit the 50% Reserve at 8:40pm. Clearly this cannot continue. Last week when it was rainy, it did not charge much. I'm interested to see what it does tomorrow starting from the Reserve SOC on a sunny day.

Thinking aloud . . . , I don't know this stuff as well you. What's the benefit of charging and discharging during the same period (partial peak in this case)? Don't the round trip loses make this a bad deal? Are there enough NBCs (non-bypassable charges) that make offset the round trip losses that it makes more sense to zero out the consumption?

I still don't have time base controls so I'm in self-powered mode. My Powerwalls are still discharging, offsetting my load right now, because my reserves are set at 70% so Tesla can debug the discharge issue that I have.

 

[miimura]

There is no intrinsic benefit to charging and discharging during the same period for Net Metered customers. Maybe the NBCs could make it worthwhile. To my thinking, it just makes the logic simpler. I'm just thinking about it from Self-Powered as the baseline functionality. By implementing my two rules on top of the normal Self-Powered behavior, I think I'm getting most of the benefits. Of course, you could make it more complicated, and it looks like that's what the Powerwall software team is going for....

So, normally in Self-Powered, you would be discharging all through the night and the Powerwall would start charging again when the solar exceeded the household load. My first rule (no Off-Peak discharge) would force the Powerwall into Standby during the Off-Peak hours. As soon as the Part-Peak period started, it would revert to Self-Powered, which for me this time of year, would mean that there would be some discharge until about 8:30-9:00 when the sun is high enough and the morning activities are done. That is probably 0.5-1.0kWh net battery drain for me. Then the batteries are just soaking up the excess solar until they are full or the Peak Period starts. Of course, you could keep the no-discharge rule active through the Part-Peak period and still allow it to soak up all the surplus solar.

It's really the lack of charging during Part-Peak that's bothering me.

 

[abasile]

What's the benefit of charging and discharging during the same period (partial peak in this case)? Don't the round trip loses make this a bad deal? Are there enough NBCs (non-bypassable charges) that make offset the round trip losses that it makes more sense to zero out the consumption?

I'm on NEM 1.0, so NBCs aren't a factor. However, I'm fine about incurring those round trip losses (roughly 10%) during the "shoulder" aka. "part peak" hours for a couple of reasons:

- California's SGIP rebate requires the equivalent of 52 cycles of the PW per year, or an average of 3.9 kWh/day for those of us with two PWs. I'm not confident that we consistently use enough "peak" electricity to achieve that much cycling, so it makes sense to cycle during the shoulder hours as well. (The majority of our electric usage comes from charging EVs at night, on "super off peak".)

- It's better for the grid and for the environment, particularly during the evening shoulder hours (8pm - 10pm in our case). There's a lot of grid demand during those hours and most of that demand is generally met with fossil fuels, potentially using less-efficient peaker plants. This isn't necessarily reflected in our current SCE TOU schedule.

Speaking of what's best for the grid and the environment, I'd prefer to be able to wait until roughly 10am or 11am to start charging the PWs from solar. The goal would be to facilitate the wider use of as much midday solar production as possible, particularly this time of year when commercial solar plants find themselves having to curtail production.

I suppose it would be ideal for the environment if we were to use a large portion of our stored daytime solar energy to charge our EVs, but it wouldn't be enough, and it would make no sense economically with the current TOU schedule. Our super off peak rate is about $0.12/kWh, versus $0.27 during the shoulder period and $0.36-$0.48 during peak.

 

[NuShrike]

I'm only going into my 2nd month of NEM 2.0, but NBCs seem to be saving me money.

I have optional loads that just generated around ~$6 of NBCs last month. That's better than $10 minimum I would've had to otherwise pay if I was zero or negative on the month. This should be the same as charging EVs only overnight.

 

[Dborn]

I have my reserve set to 10%. On a day when sun in the morning is insufficient to feed the house and battery, it will charge from shoulder or what you call part peak in readiness for the peak starting at 2pm. It charges to a variable level on off peak overnight ready for the morning part peak. That is all great. However, I get this weird discharge during off peak starting at around 4.30am for which I have no explanation. There is nothing causing a sudden draw at that time. It was for that reason I phoned support, to be told to wait a month before calling again if this behavior continues, as clearly round trip losses during off peak are not acceptable.

 

[liuping]

A new version of the iOS app came out today (3.3.5). It displays the TOU periods on the energy usage graph, which is nice.

 

[Dborn]

Scroll down further, there are other nice little tweaks....

 

[AnthonyB]

Scroll down further, there are other nice little tweaks....

I'm confused now. Below that I'm just seeing the % breakdown by source. Wasn't that there previously?

 

[miimura]

I'm confused now. Below that I'm just seeing the % breakdown by source. Wasn't that there previously?

Mine doesn't show percentages, it shows kWh per "circle", in and out as appropriate. This is not new.

 

[Dborn]

I'm confused now. Below that I'm just seeing the % breakdown by source. Wasn't that there previously?

I have not seen that previously.

 

[GKPW2]

Mine doesn't show percentages, it shows kWh per "circle", in and out as appropriate. This is not new.

The percentages only show up when selecting one source. But if you select two or more sources, it will then show kWh and direction for each source. See below. The left side shows just percentages when selecting one source. The right side shows two sources but kWh display instead of %.

 

[miimura]

I have not seen that previously.

No doubt that's due to Tesla's excellent UI design [/sarc]. There is no visual cue that there is anything more to be had by scrolling, yet there frequently is.

 

[miimura]

The percentages only show up when selecting one source. But if you select two or more sources, it will then show kWh and direction for each source. See below. The left side shows just percentages when selecting one source. The right side shows two sources but kWh display instead of %.

More UI genius. Only Home and Solar show percentages. Powerwall and Grid on show to/from kWh - From Grid or Powerwall above the chart and To Grid or Powerwall below the chart, which is hidden until you scroll. Brilliant.

 

[GKPW2]

More UI genius. Only Home and Solar show percentages. Powerwall and Grid on show to/from kWh - From Grid or Powerwall above the chart and To Grid or Powerwall below the chart, which is hidden until you scroll. Brilliant.

Correct.
But if you select Home and Solar together, they show kWh. Which kinda makes sense since powerflow is really is in one direction. To the House and From Solar.
Took a few goes to see what combo results in the display.
I found that with a lot of apps (iOS and Android), scrolling reveals hidden info. So, I've learnt to scroll any screen to see if there's anything hidden.

 

[GKPW2]

My Tesla app updated to 3.3.5 last night but still on 1.15.1.... and no sign of TBC yet...... :-(

Just weird how different people are getting different/missing features on different/same versions. Tesla is taking a very haphazard approach to firmware/software updates. If Spock was looking at it, he would say there is no logic to it.

 

[SRO-Sean]

Just weird how different people are getting different/missing features on different/same versions. Tesla is taking a very haphazard approach to firmware/software updates. If Spock was looking at it, he would say there is no logic to it.

The problem is really that most of us want to know WHY, rather then just WHAT .

In our case, the interconnect agreement paperwork simple hadn't been filed with our local utility. There's likely a setting in their system to toggle certain options regardless of software or firmware versions based on legal/paperwork status.

 

[miimura]

The Balanced setting in Time Based Control is much more to my liking.

The key point is that it is charging from all solar in the morning and then when it reaches a higher SOC, it charges from surplus solar. My previous reactions to the way Cost Saving was performing were a little bit of an over-reaction. Since it had already exported a bunch of solar during Peak hours, letting the Powerwall drain down to the Reserve and forcing the house to draw from the grid during the very end of the Peak period was not the end of the world. However, with the Balanced setting I am still getting all the benefit of maximized export during Peak and no discharge during Off-Peak, while still staying away from the Reserve end of the SOC.

This is yesterday's chart for reference, on a partly cloudy day. Today was full sun, so the battery got to 100% even before the Peak period started. The lighter gradient shading and Off-Peak & Peak labels at the bottom of the screen shot are new features of this week's iOS app release.

 

[Brovane]

Has anyone gotten the TOU options that is running Android?