[Robotbeat]

A little annoying they don’t mention cost per kWh, just “1/10th of lithium ion” which could mean almost anything. If you say lithium ion costs $1000/kWh (not far from short-lived grid lithium ion or residential), then maybe they’re $100/kWh. Or perhaps they’re using $125/kWh and they’re really $12.50/kWh.

Also, working for 150 hours is no great feat. Just means they undersized the inverter and power electronics. If you did that with lithium ion, you’d also have much lower cost per kWh (for small systems with only an hour or two, the inverter could be half the cost or more), so going to 150 hours would also reduce costs by a lot as you’d be closer to the raw cell price.

I suspect that unless there’s a chemical reason why they have to discharge over many days, any real system is likely to be more like 12-24 hours as you’d be wasting the usefulness of the battery by picking an impractically small inverter.

Here’s hoping it’s actually a huge cell cost reduction while keeping decent round trip efficiency and cycle life.

[DeRock]

There’s more details in the WSJ article: https://archive.is/2I7aq

$6/kWh raw materials, or $20/kWh for full system