> All the energy storage products I've heard about cost more or about the same per kWh just to store the energy. So even if the energy to charge the energy storage was free, it still would not make economic sense to store energy if you have grid power.

1) They are re-usable. Power generation [e.g. Solar Panels] to refill them is frequently inconsistent enough that you will need to go 12+ hours without power. Cycle through enough time and paying a multiple of grid power for energy storage that lasts years is worth it.

2) If I lose grid power [happens a couple times a year] I need backup power.

EDIT:

Iirc, I'm pretty sure Powerwall and such is ~$.30/kwh with generation included and I know I eat ~$.30/kwh for a certain level of usage.

https://www.sce.com/wps/portal/home/residential/rates/Standa...

http://www.forbes.com/sites/christopherhelman/2015/05/01/why...

$.15/kwh during the day and $.30/kwh at night is actually comparable depending on usage.

If you don't want to do generation, you can arbitage rates at $.15/kwh storage + $.14/kwh charge from grid:

https://www.sce.com/wps/portal/home/residential/rates/Time-O...