[pydry]

Storing became cost effective last year: https://ieefa.org/ieefa-grid-scale-battery-costs-have-reache...

>If storing energy were cost effective you could make a killing buying low and selling high on the national grid.

Maybe not a killing but you could make $$$ yes. This is starting to happen.

[tpmx]

You're not understanding that correctly. They are talking about things like https://en.wikipedia.org/wiki/Hornsdale_Power_Reserve

This giant (world's largest!) and very expensive thing provides short term-relief against grid outages. The batteries last for ~1 hour and it can still only provide electricity for something like 50k homes.

(It's used for more economically useful things, like stabilizing the grid in emergencies.)

The periods between high and low/zero wind are in the order of 200-300 hours (at least where I live).

[pydry]

And it was built in 2017. And battery prices have plunged since then. And it's not the only project mentioned.