Tesla Virtual Power Plant in CA

[gsdubs]

Very interesting. Looks like VPP in CA will be moving to an average kW model more similar to Eversource (New England) Connected Solutions program, which compensates $225/kW for up to 60 events, up to 3 hrs ea, for a battery's "contribution" which is its total discharge during an event, vs the discharge above a "normal" baseline. See link. So customers who discharge 5kW average across all events in a season would have to be willing to discharge up to 900kWh, and would receive $1125, or $1.25/kWh.

For the new CA program, customers like me with one PW2 with max discharge of 5kW would have to be willing to discharge up to 350kWh (35 events, 2hrs ea) and would receive $322.75, or $0.92/kWh. No more fussing about "discharge above baseline" calculations. Overall earning potential is more compared to 2023 and prior years, but at the cost of more kWh contributed, most likely.

For reference, my 2023 total discharge (not the discharge above baseline) was 66kWh and my payout was $106, or $1.60/kWh

 

[Redhill_qik]

Can someone translate this into some likely payout examples?

If you plan on participating in all events and you expect to be able to discharge at the maximum 5kW rate for the entire event period (up to 2 hours) then your payment would be num_powerwalls * 5 kW * $64.55/kW or num_powerwalls * $322.75.

To get to the 5kW rate for the entire 2 hours requires at least 10 kWh in the Powerwall. Assuming a 13.5kWh starting level, that you would leave 3.5kWh and a VPP reserve setting of 25%. I would use 20% to be safe due to Powerwall guard banding as you approach 0%.

A lot of people won't be able to discharge at the full rate as the site export limit will be less than this (mine is 7.53kW and I have two Powerwalls). Then you have to consider how much solar generation is happening and your house load. So, if your export limit was 10.0 kW and solar was generating 3.3 kW and your house load was 2.2 kW then the maximum your Powerwalls could export would be 10.0 - 3.3 + 2.2 = 8.9kW or 4.45kW/Powerwall. There is also the possibility that Tesla will limit the export as well instead of going to the maximum which they did several times last year.

If you participated last year then I would suggest that you look at the Powerwall data from August 28, 29 & 30, 2023 (see @swedge prior post with some dates) to see what your system did during a VPP event. For my system I had

• 8/28 - 6.4-9.4kW = 3.2-4.7kW/Powerwall
• 8/29 - 4.4-6.0kW = 2.2-3.0kW/Powerwall
• 8/30 - 6.2-8.2kW = 3.1-4.1kW/Powerwall

The individual increments are averaged over the entire event hours.

Note: You can go to a specific day in the Powerwall graph by tapping the Day pulldown menu and then clicking the Choose Date at the bottom of the list.

 

[sorka]

If you plan on participating in all events and you expect to be able to discharge at the maximum 5kW rate for the entire event period (up to 2 hours) then your payment would be num_powerwalls * 5 kW * $64.55/kW or num_powerwalls * $322.75.

To get to the 5kW rate for the entire 2 hours requires at least 10 kWh in the Powerwall. Assuming a 13.5kWh starting level, that you would leave 3.5kWh and a VPP reserve setting of 25%. I would use 20% to be safe due to Powerwall guard banding as you approach 0%.

A lot of people won't be able to discharge at the full rate as the site export limit will be less than this (mine is 7.53kW and I have two Powerwalls). Then you have to consider how much solar generation is happening and your house load. So, if your export limit was 10.0 kW and solar was generating 3.3 kW and your house load was 2.2 kW then the maximum your Powerwalls could export would be 10.0 - 3.3 + 2.2 = 8.9kW or 4.45kW/Powerwall. There is also the possibility that Tesla will limit the export as well instead of going to the maximum which they did several times last year.

If you participated last year then I would suggest that you look at the Powerwall data from August 28, 29 & 30, 2023 (see @swedge prior post with some dates) to see what your system did during a VPP event. For my system I had

• 8/28 - 6.4-9.4kW = 3.2-4.7kW/Powerwall
• 8/29 - 4.4-6.0kW = 2.2-3.0kW/Powerwall
• 8/30 - 6.2-8.2kW = 3.1-4.1kW/Powerwall

The individual increments are averaged over the entire event hours.

Note: You can go to a specific day in the Powerwall graph by tapping the Day pulldown menu and then clicking the Choose Date at the bottom of the list.

I have 3 powerwalls. Seems like per kwh, this is a better deal than it was before. I'm used to charging to 100% and turning everything off so that I can discharge them entirely over the 3 or 4 hour events. The year before, the payout was $538. Last year was only $305 with fewer events for the entire season compared to the season before.

 

[Redhill_qik]

I have 3 powerwalls. Seems like per kwh, this is a better deal than it was before. I'm used to charging to 100% and turning everything off so that I can discharge them entirely over the 3 or 4 hour events. The year before, the payout was $538. Last year was only $305 with fewer events for the entire season compared to the season before.

I don't think we can say "per kwh, this is a better deal", but I do think that it will be a better deal than before as there is no longer the prior day baseline subtraction.

The Tesla VPP page says that there will be a maximum of 60 hours of event time. This is lower than the CEC page that says a maximum of 35 events and if they were all the 2 hours long that would be 70 hours. Using the 60 hours * 5 kW for a total of 300 kWh with a total payment of $322.75 is just $1.076/kWh versus the $2.00/kWh last year. On the other hand if there was only a single event per month that would be 5 events * 2 hours/event * 5kW = 50 kWh and the rate would be $6.455/kWh. So, this is quite a wide range in price per kWh, but the full season compensation is still the same based on the program rules.

There isn't any requirement that Tesla commands the Powerwalls to export their maximum, so we will need to wait and see what happens in each event. I expect that there will be a single test event in May which will be our first indicator.

 

[miimura]

I don't have anything to contribute regarding the new scheme, but I did finally get a paper check from Tesla for 2023 VPP. I have two Powerwalls and never observed them discharging anything more than my household consumption. ie. never discharged battery to grid. The check was for $199.75.

I would be happy to discharge extra energy from the battery into the grid, but for whatever reason the behavior of my system never deviated from normal Time-Based Control strategy. This is especially true now that I have increased my solar size and can recover the battery energy much earlier in the day.

 

[Redhill_qik]

If you plan on participating in all events and you expect to be able to discharge at the maximum 5kW rate for the entire event period (up to 2 hours) then your payment would be num_powerwalls * 5 kW * $64.55/kW or num_powerwalls * $322.75.

To get to the 5kW rate for the entire 2 hours requires at least 10 kWh in the Powerwall. Assuming a 13.5kWh starting level, that you would leave 3.5kWh and a VPP reserve setting of 25%. I would use 20% to be safe due to Powerwall guard banding as you approach 0%.

A lot of people won't be able to discharge at the full rate as the site export limit will be less than this (mine is 7.53kW and I have two Powerwalls). Then you have to consider how much solar generation is happening and your house load. So, if your export limit was 10.0 kW and solar was generating 3.3 kW and your house load was 2.2 kW then the maximum your Powerwalls could export would be 10.0 - 3.3 + 2.2 = 8.9kW or 4.45kW/Powerwall. There is also the possibility that Tesla will limit the export as well instead of going to the maximum which they did several times last year.

If you participated last year then I would suggest that you look at the Powerwall data from August 28, 29 & 30, 2023 (see @swedge prior post with some dates) to see what your system did during a VPP event. For my system I had

• 8/28 - 6.4-9.4kW = 3.2-4.7kW/Powerwall
• 8/29 - 4.4-6.0kW = 2.2-3.0kW/Powerwall
• 8/30 - 6.2-8.2kW = 3.1-4.1kW/Powerwall

The individual increments are averaged over the entire event hours.

Note: You can go to a specific day in the Powerwall graph by tapping the Day pulldown menu and then clicking the Choose Date at the bottom of the list.

When I originally wrote this, I had picked a couple of low/high points from the graph in the app. Downloading and analyzing the 5 min increment Powerwall data resulted in the following for my two Powerwalls:

Date​	Event Hours​	Min (5min)​	Max (5min)​	Avg​
8-28-2023​	3​	6.4​	9.1​	7.60​
8-29-2023​	5​	3.6​	6.0​	4.72​
8-30-2023​	3​	6.2​	8.6​	7.63​

The longer event of 5 hours curtailed the export from my two Powerwalls to ensure that it would deliver a consistency flow for the entire period, while the shorter events of 3 hours mostly maxed out the export while factoring in my solar generation, house load and maximum site export limit. This resulted in an average of 6.30kW for the 11 hours across the three events. My expectation for 2024 with only 2 hour event periods is that my Powerwalls will be able to deliver an average of 7.6 kW across all events which should result in a payment of ~$490. This would be a significant increase from my 2023 ($240.80) and 2022 ($322.97) payments.

 

[aesculus]

The longer event of 5 hours curtailed the export from my two Powerwalls to ensure that it would deliver a consistency flow for the entire period, while the shorter events of 3 hours mostly maxed out the export while factoring in my solar generation, house load and maximum site export limit.

During the event did your PWs try to guess what the entire output would be to get you to your reserve at the end of the period? On my events they seemed to just dump the max power until they ran out, often an hour before the event curtailed, which meant I was using grid power during the last hour.

 

[Redhill_qik]

During the event did your PWs try to guess what the entire output would be to get you to your reserve at the end of the period? On my events they seemed to just dump the max power until they ran out, often an hour before the event curtailed, which meant I was using grid power during the last hour.

My understanding is that there is Tesla VPP fleet wide controller that is instructs each Powerwall how much to discharge and when. Based on comments from past events there is variability from site to site.

In 2022 the control software appears to have been mostly brute force and it did dump everything that it could within the bounds of the maximum site export limit which lead to power delivery reductions over time as systems hit their reserve levels and dropped out. In 2023 it seems like there was experimentation during the events, especially the test events. My personal experience is that most 2023 events started off at a lower export rate and then ramped up over time. In some cases my Powerwall exports were maxed at 5kW/Powerwall, but in other events it was significantly lower and well below my site export limit as well. I don't think that I hit my reserve level before the end of any the events.

I would expect that there also grid balancing attempts happening, with congested parts of the grid getting higher Powerwall export commands and uncongested parts of the grid getting lower export commands.

 

[BGbreeder]

My understanding is that there is Tesla VPP fleet wide controller that is instructs each Powerwall how much to discharge and when. Based on comments from past events there is variability from site to site.

In 2022 the control software appears to have been mostly brute force and it did dump everything that it could within the bounds of the maximum site export limit which lead to power delivery reductions over time as systems hit their reserve levels and dropped out. In 2023 it seems like there was experimentation during the events, especially the test events. My personal experience is that most 2023 events started off at a lower export rate and then ramped up over time. In some cases my Powerwall exports were maxed at 5kW/Powerwall, but in other events it was significantly lower and well below my site export limit as well. I don't think that I hit my reserve level before the end of any the events.

I would expect that there also grid balancing attempts happening, with congested parts of the grid getting higher Powerwall export commands and uncongested parts of the grid getting lower export commands.

Our experience is similar.

FWIW: While we are in the same general area, the discharges here also seemed more nuanced in 2023, with varied rates. I remember one in particular that seemed as if it was designed to demonstrate some level of production, as the date and time of the event did not coincide with local or CAISO reported outages, or peak demand.

All the best,

BG

 

[aesculus]

In 2023 I only participated in 2 events after the terrible experience of 2022. So I will attempt to be more involved this season from the reports you have all given here on you experiences last year and the new rules around how compensation is determined.