For households, people are commonly using 1-1.5 KW system. A typical household would need a 4KW system to be fully self-sufficient for electricity - feeding into the grid during the day, drawing electricity at night, when demand is low, so not much storage needed. Also peak and off-peak pricing will change to match patterns of both use and production, which will further drive consumer patterns to use the existing power efficiently. They basically pay people right now to use more power at night: with solar the incentives will turn around, so it's wrong to look at existing usage patterns to decide how much battery backup we'd need in a 100% solar set-up. We'd have to take into account that power costs in the day would be when prices are cheapest, and they'd become more expensive overnight, which is the opposite of what happens now. Households, but especially heavy commercial users would change their behavior in those circumstances. Higher night prices would cover the needed battery storage, while disincentivizing night-time consumption, so it's a no-brainer that things would compensate pretty quickly for an all-solar world.
So it's not really a big stretch that entire communities are completely self-sufficient from home solar, especially if future systems are more efficient than current. The main thing would be to arrange financing to get the capacity, in a similar way to how we do other types of social insurance.
Additionally, rather than just molten salts or the like to store energy, why not just pump towers full of water? We need to do that anyway, and the water can turn turbines when people get some water. We could couple that with off peak water pricing e.g. at times when power is worth more, you make water a bit cheaper. Companies that need a lot of water are then going to choose to use more at night, which in turn released stored electricity when it's needed.