The point is to shift how much power you generated for several off-peak hours to the on-peak hours, not to be totally energy independent for some allotted time.

The point is to shift how much power you generated for several off-peak hours to the on-peak hours, not to be totally energy independent for some allotted time. For example, say you can store up 10 kWh of excess energy during the noon sun when it's worthless. If peak is from 5 to 9, you only need a 10 kWh pack that can discharge in 4 hours.