Re: The Physics Behind the Spanish Blackout

On 6/12/2025 6:36 PM, KevinJ93 wrote:

 >> I calculated the cost of the wear and tear on the battery is (very)
 >> approximately $0.25/kWh.
 >
 > So, if you have a surplus, it makes sense to make it available (even though
 > whether or not you have a buyer may be uncertain on any given day)
 >
 >>  > 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.
 >
 > We use about 25KWHr/day (it's not "hot" yet).  So, would need to generate
 > about 50KWHr daily to meet that sort of storage ability.  Without
 > resorting to
 > a tracking collector, I think we're limited to about 6.5 usable solar hours
 > daily.  So, would need ~8KW from an array to "bank" that much.
 Our usage is very similar (somewhat higher in peak summer - last July 4th we consumed ~70kWH).

Our daily *average* will approach that (about 65KWHr) once it gets hot.
Or humid.  (Or both).  So, 50KWHr won't even meet our daily needs
(assuming we could bank it without having to take a loss using
the grid as that bank)

The peak AC output of my solar array is 8.1kW - you made a very good estimate.

 >> A couple of times there have been emergencies where there has only
 >> been minutes of warning.
 >
 > So, you could have a "standing offer" that they could avail themselves of?
 > The rate of compensation doesn't vary with the severity of their *need*?
 Currently the pricing is static for these residential energy storage systems but commercial ones do use dynamic pricing.

Abusing (?) residential contributors because they can get away with it?
(I'm assuming commercial users are bigger loads and more attractive to
engage)