Audi is gearing up for the advent of electric cars with a "virtual power plant" that connect homes with renewable energy sources, such as solar panels. A software system made by Swiss startup Ampard distributes energy based on needs and appliances being charged. "The network accounts for the fluctuations between the amount of energy generated and the amount actually used. And because there's less reliance on energy from outside the network, the households' energy costs are reduced," the author writes. There is not much discussion in the article about the amount of power produced cumulatively by the households as well as how the software will achieve balance during peak demand.
More details about Audi's venture are available in this post. The project also uses power from the grid. "The connected home storage devices can provide balancing power; in other words, they balance out the fluctuations between power generation and consumption, and stabilize the grid frequency by temporarily storing smaller amounts of energy in stationary units at short notice. This optimizes internal consumption."
So far, virtual power plants have been used at the grid level by utilities. According to a 2011 note by Peter Asmus, Navigant Research analyst, virtual power plants tap "existing grid networks" and "maximize value for both the end user and the distribution utility using a sophisticated set of software-based systems." It will be interesting to see the results of Audi's experiments with VPP at the level of consumers.