[IanDrake]

>This leads to what seems to be a paradoxical situation. A battery that is more expensive than the average price of grid electricity can nonetheless arbitrage the grid and save one money. That’s math.

Missing in the math is logic. If enough people do this, the price will even out and the arbitrage opportunity will vanish.

It's like an arbitrage trading a model that makes money when paper trading but loses money when live because the effects of live trades on the market wasn't considered.

[Guvante]

The fact that an arbitrage opportunity will not always be available does not mean that arbitrage opportunity does not exist.

Also electricity companies would be very slow to adjust to reduced demand by lowering prices, making this work for longer than a naive analysis would predict.

[hueving]

>The fact that an arbitrage opportunity will not always be available does not mean that arbitrage opportunity does not exist.

Spotting a leftover cookie on the table means you will probably be able to get a free cookie. It doesn't mean that you have found a way to solve world hunger.

[Guvante]

Everything you have said can be said about literally every possible opportunity to make money outside of those that leverage sweat equity.

If you want to say something about his idea that is specific you could add value.

For instance attempting this arbitrage is a risk transference since you are betting that the technology of batteries won't catch up before you have made back your capital investment.

[mikeash]

The arbitrage opportunity won't vanish, but rather it will diminish until the cost of performing the arbitrage roughly equals the money you can make from it. When the peak/off-peak price differential drops such that buying more storage isn't profitable, people will stop doing it, and the price will stabilize. It's just like any other normal market: prices stabilize at something near the costs.

[7952]

Also, it will usually be more profitable to build more generating capacity, reduce demand or improve the grid. You can build massive arrays of expensive batteries but you probably don't want to.