The economics of batteries are a function of cycle limits (none in this case, probably) and how much energy you can store and discharge over time and the price

The economics of batteries are a function of cycle limits (none in this case, probably) and how much energy you can store and discharge over time and the price difference between charging and discharging. All that minus the upfront installation cost. The article says this thing should last at least fifty years. There's no good reason it couldn't last longer as it shouldn't really degrade over time. If you assume daily charge/discharge cycles, that would be about 18250K cycles over 50 years. Times 4GWh is about 73TWh of energy sold to the grid at, hopefully, some profit. Of course that all depends on demand, utilization, and whether there are any cheaper ways to store energy. It's probably going to end up some percentage of that. But best case that's energy you buy cheap and sell at a higher price. Even a few cents difference starts adding up to billions pretty quickly. And that's before you consider the alternatives (buying energy on the open market from another provider, investing in more energy generation, etc.). The prices you cite are just the purchase price. And of course lithium batteries don't last forever. So you'd be writing them off at some point. But in fairness, there are some battery chemistries that are getting quite good cycle times. So, the comparison might become a bit more fair over time.