Re: The Physics Behind the Spanish Blackout

On 6/11/25 6:06 PM, Don Y wrote:
 >> My solar PV system has battery storage and I subscribe to Tesla's
 >> Virtual Power Plant. When the grid is under stress I allow up to 50%
 >> of the storage to be used by the grid for which I get paid $2 per kWh.
 >
 > Not bad when you consider they charge $0.15/KWHr to sell that electricity
 > to you in the first place!  You're just letting someone take your car
 > (house)
My batteries only get charged from solar (My account with PG&E does not permit charging from the  grid as that as that would allow arbitrage).
 > for a drive -- without any mechanical wear-and-tear on a vehicle, any
 > risk of an "accident", theft, etc. -- and are being reimbursed for that
 > "generosity".  Much more generous than many "friends" would be in
 > reimbursing you for their convenience!
 >
I calculated the cost of the wear and tear on the battery is (very) approximately $0.25/kWh.
 > What sort of capacity do you have and how easily do you "top it off"
 > purely from solar?
I only have 27kWh of storage (2 Tesla Powerwall units). In the summer I average 20-35kWh per day of surplus generated by solar. So if the battery has discharged to 25% (own use plus any exported) in the evening it can be fully recharged the next day.
 >
 >> I usually get a few hours notice through the App on my phone and I can
 >> opt-out for any event. This is in California although Tesla operates
 >> similar programs throughout the country.
 >
 > So, they have good enough models to *predict* when there will be a need?
 > Or, is there *always* a need and they just "spread the wealth"?
The models are usually pretty accurate (https://www.caiso.com/todays-outlook/). Among other things the next day's predicted consumption is based on historical data and weather predictions (air conditioner use is a large component of the power demand).
A couple of times there have been emergencies where there has only been minutes of warning.
 >> Tesla vehicles do not (yet) support Vehicle to Grid (V2G) operation
 >> although the extra hardware required is minimal as the conversion from
 >> AC to DC in the car is already pretty much bidirectional to achieve
 >> high-efficiency. (Just using Diodes is too inefficient)
 >>
 >>> <...>
 >