Batteries for the supply slack, hot water heater elements to dump excess power into. Concerned about enough supply? Oversize your systems.
Oversizing doesn't help when it's cloudy or the wind stops. You need diversification, which isn't always possible over small (neighborhood-sized) areas.
Oversizing is expensive unless you have a large enough group to distribute the burden. Neighborhoods might not be big enough; they would have to expand to city or county size.... but we already have a system for spreading out the demand and supply balance to larger groups.. it is called the power company.
Depending on how much diversity you need, your neighborhood could add an on-site natural gas or propane generator to the mix.
TL;DR You need to do the cost benefit on a case by case basis.
There's only so much they can do about demand correlation. Electric stoves, for instance, are likely to be used at the same time by most households. That's one reason why really good batteries would be such a benefit.