37.8 MWh is consistent with the 10 year warranty. If you divide 37.8 MWh by 13.5 kWh (Powerwall capacity) you get EXACTLY 2800 cycles. That equates to an average daily discharge of 77% over 10 years. That is probably consistent with Powerwall usage by net consumers. But, if you believe the Powerwall will last longer than 10 years if used more sparingly, then that equates to about 20 years if only drawn down by an average of 38% daily.
Nope, this would still be a (multi-)year discussion with the cpuc. Local pilots would likely be needed.
I also wonder how this would work out for the grid in this "rare event". I would think this would be in the Fall when the weather was hot. Just the time you need your Powerwalls to power your home's AC. That is when you are most likely to need the power and when using that power could offload the grid at a critical time.
Every VPP and utility could handle this differently, but for the VPP I am part of with our utility National Grid here in the east, during an “event” the power reported as delivered to the VPP includes my home load.
I think the California VPP is different than the ones that Tesla has set up elsewhere. I did opt in and do not have the grid services entry. There is a possibility it will shop up after the first event, of course. If I look at what's returned from the API for my Powerwalls, there is a flag called grid_services_enabled that is false, but energy_service_self_scheduling_enabled is true.
More than total battery output. In a weird way, during an event the battery power goes solely to the grid. I imagine this is so they can predict the output and estimate the length of time for that output to stabilize their VPP.
It does look like the CA VPP is not the same as the grid services program in other places. For one example of a difference, with grid services we do not get to control the reserve level of a battery during the event. It is set to 20% during an event and will override a user set reserve. Once the event is over, the reserve goes back to the user set amount.
And will that 10x stay there at annual true up or revert back to wholesale price? And if you are in a CCA as in Monterey county, will it still be 10x from the CCA?
Have no idea about other VPPs, but Connected Solutions is for 5 years after sign-up in New England unless the owner requests out before that time is up. We are also part of a CCA and that is not affected or changed in any way by being part of the VPP.
The Powerwalls have a 10 year warranty that they will have at least 70% capacity. The degradation of batteries after that point seems to be steep from some battery charts that I have seen, so to keep the same amount of installed capacity they will need to be refreshed at a faster rate than the attached PV.
I signed up for VPP to see what it's all about. Until we have an event I'm not sure if we will have any more substantive conversations.
Normally stickies are not needed. If a topic is popular enough, it will remain on top. If it eventually gets buried, then it ran it's course. In this case this is a topic that will keep evolving over the next few months as more information becomes available, even after a possible few weeks of inactivity. People will look here to add more to the topic (such as NEM rate information which isn't currently known). If it is buried it may not be easy to find.
Hmm, it does not appear that I can back up my claim that the degradation rate increases after the 70%/10 year point. The Tesla automotive battery data is showing a relatively flat curve vs miles driven, but there is also a very wide range in the data set. I guess we will see what happens over time, but then that data will be out of data with new improved batteries in later generations.
At least we'll still have the solar operating, hopefully, and it will not be a great tragedy if the batter is partially charged until we can decide the next step, unlike the main inverter going belly up.
