[Obi_Juan_Kenobi]

The mythical $100/kWh figure for car batteries is for the pack cost, not the cells. Much of that cost is focused on a compact, lightweight solution for cell cooling, voltage balancing for ~100 batteries in series, etc.

Utility installations have much cheaper solutions for cooling, the balancing is much easier with lots of parallel cells, and even the chemistry benefits from smaller charge/discharge currents.

We're not down to $30/kWh yet, but we're not that far off. Certainly well below $300.