Plug-in hybrids, meanwhile, could charge at night, when demand is low, and even pump power back to the grid while parked during the day.

It provides a number of user configurable plug-ins for altering the behavior of the grid.

Hundreds of the Priuses have already been converted to plug-in hybrids, in which some of the electricity comes from plugging into the grid rather than using the gasoline engine to drive a generator.