So, apparently we need a complicated system of grid feeding substations (electric cars, in this article) to help keep the grid working. Here's another idea - the utilities could do THEIR job a little better, and this vast infrastructure change will be irrelevant. How do they handle solar, wind and similar at the moment? Another issue is that overall power quality will degrade with too many cheap substations feeding energy with uncontrollable amounts of reactive power into the grid. Sure this can be handled, but only at considerable cost to the installation you need in your home. That is one the reasons utilities would rather keep your excess wind, solar, hydro or other such energy sources off their precious grid, and will settle for your consumption to be really low. Handling that situation would require substantial investments on the side of the utilities - not exactly what they are known to love.