> every (second) house would have a powerwall, wouldn't that make the grid stable?

At 131mm American households [1] and $11.5k per PoweWall [2] that’s over $750bn at 50% loading.

[1] https://www.statista.com/statistics/183635/number-of-househo...

[2] https://www.thisoldhouse.com/solar-alternative-energy/review...

China is starting to mass produce NaCl batteries. They will be cheaper.

And also only Powerwalls produced in this quantity would have way lower prices. My point was batteries are getting cheaper every day.

A powerwall is $12k installed.

That's about 5 years worth of power bills for most people.

It could be less stable, if each and every powerwall is slightly out of phase.

But this is something, one can avoid by only allowing well tuned batteries to the grid? Or is this a serious problem to get right?