Comment Re:Wouldnt NiFe be a better battery chemistry here (Score 1) 185
Cost is one reason, although NiFe is already more expensive than Li-Ion, and rapidly becoming more and more so. Particularly when EV batteries are available so cheap. They also ought to last more than a year or three. NiFe's cost also needs to take into account the fact that they require a massive increase in infrastructure compared to lithium ion. What you can do with a single building worth of lithium ion batteries would require twenty buildings of NiFe batteries. That's not an insubstantial difference!
It's also worth noting that nobody uses NiFe batteries for backups either: they use lead acid. That's not a coincidence. Lead acid is still at the point where the lower costs negate the lower efficiency, although that may eventually change.