The BIGGEST problem with clean energy

Australians can buy a zinc-bromine flow battery for their homes from RedFlow. It's called the ZCell. Unlike some other flow battery chemistries, zinc-bromine plates the zinc onto one of the electrodes during charging, then it's redissolved and put back into solution during discharge. The quirky thing about this is that all zinc _must_ be dissolved off the electrode, or it can form dendrites that will eventually short out the cell. And so every few cycles the battery must be full discharged. So after it's down to zero, it's shorted out for about half an hour just to make sure it's dead. Most practical systems will have two battery banks. When one is completely discharged and sitting there shorted out, the other has power. The ZCell is 48 volt, 220 Amp-Hour.

Curious, a few years ago I looked at the US price and it was about $15,000 (USD) delivered. Hopefully they've come down in price since then.