> A few local small-scale demonstration projects don't tell us much about the difficulties of scaling up by orders of magnitude.

The UK is forging ahead with large scale battery storage projects. I have not done the math, but I assume there is a sound economic case in order for these projects to receive this level of investment.

Edit: Here's some more data on revenue for battery storage in the UK [3]

[1] https://www.solarpowerportal.co.uk/battery-storage/statera-u...

[2] https://www.solarpowerportal.co.uk/battery-storage/fidra-ene...

[3] https://modoenergy.com/research/gb-research-roundup-january-...