Batteries will hit break-even with the split on peak vs off-peak electricity starting in a year or two.
Current retail consumer batteries (installation consisting of screw it to a wall and plug in three wires if you have a compatible inverter) are at around $280/kWh or 75c per kWh if you use it daily to load shift for one year. About 15c over 5 years. Halve that and anyone buying on peak electricity in a high-price area is going to be very interested in a battery rather than paying the next two quarters’ electricity bills. Quarter it (which is conceivable once sodium ion scales enough to meet utility demand) and average-price areas are looking at it real hard
EVs are hitting $1000/kWh pre-subsidy in the west or $300/kWh in china for the entire car. V2L or V2G becomes very appealing for anyone not using their car during the day.