This event is a bit different than others and there was no charging period set, so Powerwall charging is using your standard behavior. I want to prioritize my Powerwall charging, so I raised the reserve limit up to 90% and all of my solar is going to the Powerwall.
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Tesla Virtual Power Plant in CA
- Thread starter power.saver
- Start date
My understanding is that you can't opt back into an event after opting out.
You will remained enrolled in the program and be involved in future events.
Gone in my app also, might have been cancelled or maybe someone realized that they forgot to set the Charging time and need to restart the event.
Also gone from mine.
It may be due to lower demand forecast. Peak demand is forecast to be 46,219 Mw @ 16:45. Current capacity is 55,846 Mw
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Update: 10:42. The event is back and Powerwalls charging. All solar going to Powerwalls. Home running off grid.
It may be due to lower demand forecast. Peak demand is forecast to be 46,219 Mw @ 16:45. Current capacity is 55,846 Mw
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Update: 10:42. The event is back and Powerwalls charging. All solar going to Powerwalls. Home running off grid.
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Now from 5 - 8 pm (first notification was 5 - 6 pm)
OK, so they need to update their algorithm for the case that the above behavior would leave someone above the reserve level at the end of Peak. As then they shouldn't hesitate to also discharge during Peak before the VPP as normal. As the maximum discharge during the VPP is entirely known ahead of time.
Bascially, VPP should set a "VPP reserve" equal to the normal reserve plus the VPP maximum discharge amount. And then prioritize charging the PWs to that VPP reserve level. Then if there's any capacity left above VPP reserve, behave as normal before the VPP event, with VPP reserve instead of normal reserve.
Cheers, Wayne
I like the idea of a VPP reserve level as it would eliminate needing to remember to lower it before the event and then raising it back to normal after the event. This would allow for set-and-forget behavior for the VPP that should result in a more consistent discharges.
Reverting to normal discharge behavior before a short event would be a tricky thing to implement. Not impossible, but there would be complications. For instance the Export Everything people might end up discharging enough that they couldn't get through a 1 or 2 hour event without hitting their reserve. There might also be some VPP rules about guaranteed supply levels that might prevent it. Reverting to normal behavior afterwards is easy and already implemented. Since your reserve level is already lower than normal that should cover it in most cases.
charlesj
Active Member
Thanks. Now I know why I only transported 4kWh total from 2 batteries. Tesla software predictions, I suppose.
You're proposing a user selectable VPP reserve level with some defined meaning? I was suggesting a software defined VPP reserve level = regular reserve level + promised VPP discharge
I don't follow this comment at all. The VPP is a promise to discharge (in my case) 4 kW for say 3 hours (or until I run out). So the PWs know that the first 12 kWh above reserve (35% at the moment for me) need to saved for VPP. But anything above that can be used normally. Hence I'm suggesting it just use its normal algorithms before the VPP discharge, temporarily treating the reserve level as 35% + the 12 kWh promised.
Of course, this is all moot for me, as my PV system is small enough I'm not generating 12 kWh/day these days. But the design seems obvious to me. Although I haven't considered how it should respond if you mess with parameters during the day of the VPP event.
Cheers, Wayne
FWIW: Our system exports at 2.5kW/unit (7.5 total), and happily provides home power on top of that (e.g. 5kW to the AC).
During a VPP event, not just during "Export Everything"? And during Peak before the VPP event (if there would still be 7.5 kW * length of VPP event of energy left above reserve), not just after?
Cheers, Wayne
Right, one regular reserve level for daily Peak discharges to meet house loads and Export Everything if that is used. and a second VPP reserve level for events. I think making the VPP an adder to the regular reserve level would be confusing. For instance say you set the reserve to 80% and with a VPP adder of 60% which gets you to 20%. Then you adjust the regular reserve to 50% and now your VPP is -10%? Doesn't make sense for a user interface.
The VPP discharge doesn't work the way that you are describing it. The VPP will discharge at a rate that doesn't exceed its specification (5.0kW) and doesn't cause the grid export to exceed the PTO maximum. In my case I have two Powerwalls so that is a max of 10kW, but my PTO max is 7.86kW. If my house load is only 0.5kW then my Powerwalls discharge at 8.36kW, but if my A/C kicks on then the go up to 10kW. In your case that may be 4kW.
Using your 4kW for 3 hours that is 12 kWh from a 13.5 kWh battery leaving you with 1.5kWh or 11% with the 5% safety buffer that would show up as 6% in the app. If the event was only 2 hours then would be 8 kWh leaving you with 5.5 kWh or 40% with the 5% safety buffer that would show up as 35% in the app. There would be more left in a 1 hour event, but even then most if not all that is left should be able to be discharged before the end of Peak.
Right, so if the goal is to net export as much as possible up to the specified limit, I overlooked that the PWs also need to discharge to cover the house loads. So I overlooked that rather than reserve 12 kWh for my example, it would need to be 12 kWh plus an estimate of the house load during the VPP discharge period. Which estimate I think the system has, but it might be appropriate to use a more conservative estimate to reduce the chance of hitting the reserve level during the VPP discharge period.
So it's not as simple as I first thought, but with that update, if there's still more energy stored than reserve plus forecast VPP discharge required (max net export plus house load), there's no reason the algorithm shouldn't discharge during pre-VPP peak. On the other hand, that's only useful for the scenarios when the PWs would otherwise end up above reserve at the end of Peak.
Your description of my case was based on one PW, but I have two PWs.
Cheers, Wayne
There is one piece you are missing that I have posted about previously.
The TEG has a setting called Site Limit Export. This is not always set to the PTO maximum.
In my case the Site Limit Export is 10.8 kW (My PTO allows ~27 kW)
My experience in VPP events has been that the PWs will discharge what is needed to achieve 10.8 kW site limit; home load and PV generation are taken into consideration. If home load causes the PW to hit the max discharge (seems to be 14.8 / 14.9 kW for 3 PW2s) then the grid export will be limited accordingly.
Effectively this means my 3 PWs are pegged at 14.9 kW until they hit the reserve %.
IMHO, the goal is to have the Powerwalls discharge as much as possible during the event period and to the extent possible to minimize the discharge during high likelihood event hours in the baseline days before. That might mean that if your normal Peak usage is say 12kWh and you have two Powerwalls that you use Export Everything with a reserve limit of 51% (56% - 5% buffer, but might be different due weird app sliding scale) so that most of your baseline exports are from 4:00-6:00pm with a small amount from 6:00-6:30pm. Then on event days you discharge down to your comfort level from 6:00-9:00pm with a near zero baseline and get the maximum compensation value. This is basically how I have mine set up now.
If you meant 4kW per Powerwall then the percentages are still the same, but the kWh left would be doubled. If you meant 2kW/Powerwall and 4kW total that seems unusual and must mean that your solar invertor/PTO is only rated for 4kW. Have you looked at any of your baseline numbers to see if this is even worth it to you?
I do not do "export everything". The current (couldn't resist
) export limit is set by the Gateway. I haven't dug into why the number is 7.5kW, but given the day length, and the size of our solar array, it seems to me to be a reasonable setting. So far we have been able to sustain the export for three to four hours, and just hit the reserve setting most days.All the east,
BG
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