Saying that grid storage "only has a few hours of capacity" is like saying that a nuclear power reactor "only has 1GW of power." You solve both issues by deploying more. And if you want a longer lithium ion battery installation without the additional power capacity, you can save a bit on inverters.
Grid storage is cheap enough that Texas, a purely profit-driven grid is now overtaking California in the amount of battery storage deployed. 58GWh of new grid storage was added in 2025 alone, and the growth is still exponentialhttps://seia.org/news/united-states-installs-58-gwh-of-new-e...
All current grid storage will fully discharge in less than 4 hours at max watts. It is designed to level daily demand variability. To make a 4 hour battery last for a week at the same wattage would make it cost 42 times as much.
Yes, this is how the basic arithmetic works. What's your point?
I see now that your original post had a fantastical claim that we need weeks of battery storage, which is a fantastical claim. In reality we will need variable amounts of battery but a "week long" battery is not supported by a single detailed grid study I have ever seen.
When I have asked Pell to justify claims of "weeks long battery" the only justifications have been "I heard it from someone else", or napkin math that contains many errors, and in places where there are not errors choices are made to estimate an upper bound rather than a lower bound, indicating that the calculator doesn't understand how napkins math can be useful.
And for super cheap infrequently used storage, here's a recent purchase at $33/kWh of a 30GWh battery by Google:
I don't expect such batteries to be used much, despite being a fraction of the cost of current LFP batteries, because we really won't need much storage with such a low power:energy ratio.
Also, 5 was a typo, it should have been 4 of course! Form energy has been making a major splash for years, having first modeled out the grid case for this type of battery, and ensuring that all materials and battery chemistry allowed a potential route to success. It's iron-air.
Grid storage is cheap enough that Texas, a purely profit-driven grid is now overtaking California in the amount of battery storage deployed. 58GWh of new grid storage was added in 2025 alone, and the growth is still exponentialhttps://seia.org/news/united-states-installs-58-gwh-of-new-e...