Path: news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: Don Y <blockedofcourse@foo.invalid>
Newsgroups: sci.electronics.design
Subject: Re: The Physics Behind the Spanish Blackout
Date: Fri, 13 Jun 2025 01:03:01 -0700
Organization: A noiseless patient Spider
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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)