Daylight Saving, PG&E & Powerwall

[miimura]

I am on PG&E in Northern California. PG&E's rate schedules still follow the Daylight Saving Time schedule that was abandoned in 2007. That means that from the second Sunday in March to the first Sunday in April, the rates schedule is shifted 1 hour later. Now that the vast majority of metering in PG&E territory is done by Smart Meters, the fact that the Utilities Commission allows this to continue is a little ridiculous.

Anyway, on to my point. I went into the Tesla app to shift the schedule later to match my utility's billing and I found that it was already adjusted. This was a pleasant surprise. Anyone want to wager whether it will adjust back in April?

The normal schedule is Peak 2-9pm Weekdays and 3-7pm Weekends.

 

[MorrisonHiker]

Hmm. I just checked mine and it's not a pleasant surprise to see it added an hour to my time periods when it shouldn't have. It's possible it would correct itself tonight but I'll just manually change it back myself...and hope it doesn't reset them again tomorrow.

Actually, I just tried setting one of the periods to 2 am and found that it doesn't allow that. I guess this might be the Daylight Saving bug I've heard about. Guess I'll just reset things tomorrow!

 

[zanary]

I am on PG&E in Northern California. PG&E's rate schedules still follow the Daylight Saving Time schedule that was abandoned in 2007. That means that from the second Sunday in March to the first Sunday in April, the rates schedule is shifted 1 hour later. Now that the vast majority of metering in PG&E territory is done by Smart Meters, the fact that the Utilities Commission allows this to continue is a little ridiculous.

Anyway, on to my point. I went into the Tesla app to shift the schedule later to match my utility's billing and I found that it was already adjusted. This was a pleasant surprise. Anyone want to wager whether it will adjust back in April?

The normal schedule is Peak 2-9pm Weekdays and 3-7pm Weekends.

View attachment 384972 View attachment 384973

Mine also shifted based on the dates as outlined in the EV-A tariff so I’m happy it did change. I’m sure it will change the times as per the same tariff when it needs to.

 

[LaMort66]

I'm on PG&E also, and I thought it was a glitch when I saw this change in the app. I forgot about the old daylight savings dates in the ToU tariff. I searched for and found this post because even with the corrected price schedule, the PWs stopped discharging at 7pm instead of 8pm. They normally discharge through the end of peak, depending on SoC. I'm well above that at 89% at the end of peak since it was quite sunny today. The time on the app appears current. Did anyone else have the same result?

 

[cwied]

As a software engineer I'm somewhat familiar with conventions on how time is dealt with in applications like this. Typically times are stored in a time format that is absolute (either Coordinated Universal Time or a count of milliseconds or seconds since an arbitrary time called an epoch). and then translated to local timezones. Shifting by an hour is exactly what would happen if times are stored this way and not adjusted. If I had to wager money, I would bet there will be no shift in April when PG&E catches up to DST. I also suspect that if you go traveling to a different timezone, the schedule would be shown in that timezone as opposed to the timezone at home.

 

[miimura]

As a software engineer I'm somewhat familiar with conventions on how time is dealt with in applications like this. Typically times are stored in a time format that is absolute (either Coordinated Universal Time or a count of milliseconds or seconds since an arbitrary time called an epoch). and then translated to local timezones. Shifting by an hour is exactly what would happen if times are stored this way and not adjusted. If I had to wager money, I would bet there will be no shift in April when PG&E catches up to DST. I also suspect that if you go traveling to a different timezone, the schedule would be shown in that timezone as opposed to the timezone at home.

Actually, when I was overseas, the app gave the times and listed them as PST, seemingly knowing that I was not in the same time zone as the installation.

 

[cwied]

Nice. I guess I gave them too little credit.

 

[zanary]

As a software engineer I'm somewhat familiar with conventions on how time is dealt with in applications like this. Typically times are stored in a time format that is absolute (either Coordinated Universal Time or a count of milliseconds or seconds since an arbitrary time called an epoch). and then translated to local timezones. Shifting by an hour is exactly what would happen if times are stored this way and not adjusted. If I had to wager money, I would bet there will be no shift in April when PG&E catches up to DST. I also suspect that if you go traveling to a different timezone, the schedule would be shown in that timezone as opposed to the timezone at home.

Also remember, what're re describing here is an edge case because PG&E has this really weird rule and doesn't follow the DST standards in terms of actual date of flipping to DST. What we're seeing here is not any special calculation with the date time format as you indicate above, but one where Tesla had to code an edge case to allow compliance with the EV-A Tariff from PG&E.

I call it an edge case as I have not seen such weird rules from other electric companies who offer a similar tariff (however I could be completely wrong here as well).

Source for latest EV-A Tariff = https://www.pge.com/tariffs/assets/pdf/tariffbook/ELEC_SCHEDS_EV (Sch).pdf

Specific time requirement from PG&E

 

[cwied]

What we're seeing here is not any special calculation with the date time format as you indicate above, but one where Tesla had to code an edge case to allow compliance with the EV-A Tariff from PG&E.

Actually I was trying to say that while it is possible that Tesla does store the schedule in local time and did code the edge case, I think the more likely explanation is that they simply didn't code in any changes for the daylight-saving switchover and the apparent shift is just a side-effect of storing the timestamp in UTC. I'm especially suspicious given the report above that @MorrisonHiker who isn't in the PG&E service area had the same shift.

We will be able to tell for sure which way it is in April. I'm expecting that there will be no shift then. If there is, I'll be happily surprised and concede that Tesla engineers are putting in more effort to this area than I thought.

 

[LaMort66]

I think cwied might be correct here about it being UTC-related. I was just revisiting this to see if there was any other insight. I noticed that while the Price Schedule in my app shows the peak time to be from 4pm-8pm, the light gray peak deliniation in the timeline still shows it's from 3pm-7pm. If I switch it to 5pm-9pm, it will move to 4pm-8pm in the timeline. It might just be because the app can't handle the hour that we skipped today too. I guess I'll see tomorrow.

 

[miimura]

Ok, I just noticed some more weirdness. Even though the schedule in the app was set for 4-8pm, the Powerwall actually discharged from 3-7pm. On top of that, the shading in the intraday chart for the Peak period was shifted about 20-30 minutes to the right. The tiny solar peak at the left edge of the gray stripe is at 15:20.

 

[power.saver]

All my settings returned to normal just after midnight.

 

[Frankman60]

For San Diego SDG&E customers, has the utility fixed the daylight savings time issue where it is off by one hour as the OP stated for PG&E?

 

[Shygar]

FYI I checked this today and found that none of my pricing schedules showed up. I switched it from balanced to cost savings, then immediately back to balanced. Edited the schedule again and it came back to what I had it set to before (2pm to 9pm EV-A rate peak, etc). I'm just going to leave it as is so I don't miss the switch back in April.

 

[miimura]

Mine also reverted back to the original schedule. I manually adjusted it for the 1 hour PG&E offset because it will be 4 weeks. If it was only one week I would just leave it alone. In order to move the Off-Peak from 11pm to Midnight, you have to slide the control to the far left. It will only let you drag to the right as far as 11:30pm.

 

[cwied]

All my settings returned to normal just after midnight.

Ah, so it seems like they do shift the schedule for DST, just a little late. My schedule also looks like it was shifted by an hour from what I set yesterday.

 

[Ulmo]

a little ridiculous.

A lot ridiculous.

Ok, I just noticed some more weirdness. Even though the schedule in the app was set for 4-8pm, the Powerwall actually discharged from 3-7pm

Mine also reverted back to the original schedule.

Sigh. All of this is so easy to fix. YET THEY DON'T. Centralized places never do.