At the heart of HaoHan is BYD’s self-developed 2,710 Ah Blade Battery cell, which the company claims is the largest energy storage cell in the world. This next-generation cell delivers three times the capacity of conventional storage batteries, boasts a cycle life of over 10,000 cycles, and reduces the total lifecycle cost per kilowatt-hour to below CNY 0.1 ($0.014) – a milestone that could reshape the economics of large-scale storage.

At 1.4 cents per kilowatt hour to store, that actually puts storage cost below generation cost for solar power. In sunny regions solar without storage has been cheaper than fossil generation for a few years now, but with batteries like these it's going to be cheaper than fossils for overnight usage too.

The other exciting thing is that while this is a Chinese product, we can expect similar cost drops outside of China over time. Today's non-Chinese solar cells are about where Chinese solar cell prices were 5-9 years ago. China gets the low prices first, but global manufacturing costs keep dropping too because the lower costs are driven more by technological improvements than by China-specific factors like inexpensive labor or lax environmental standards.

I wonder what active inertia response is and why it is limited to 25 seconds.

The normal rotating machines have inertia, stored rotational kinetic energy, so when electrical load is added and mechanical power in does not immediately change they new load is fed by the generator very slightly Slowing down and measured by a decreasing frequency.

How would active inertia be different from the inverter simply putting out more power when frequency drops?

Since these are so small, we could augment the last neighborhood level transformers with these and upgrade the local grid. Home solar could charge into these, we really could do peak shaving at the local level.

The other use would be for data centers to buy when power is cheap and shave their peaks as well.

I am very bullish on utility scale batteries.