There was a project to try this: https://www.greentechmedia.com/articles/read/german-utility-plans-a-flow-battery-big-enough-to-power-berlin https://www.greente

There was a project to try this: https://www.greentechmedia.com/articles/read/german-utility-plans-a-flow-battery-big-enough-to-power-berlin https://www.greentechmedia.com/articles/read/german-utility-... Unfortunatly this project was cancelled since Germany taxes electricity from batteries two times: Once when charging the battery and once when discharging it (since it is then seen as "producing" electricity).