Not a massive "if" at all. Here is how it works. You buy an electric car and keep it plugged in. You charge it when energy costs are low, and SELL electricity back to the grid when rates are high. This is assuming you want to make some spare cash while your car is parked. Most cars will be out driving during at least part of the daylight hours when solar power is being generated. As the sun goes down the car can sell some of its leftover power while demand is still high but solar power is unavailable. The battery will be recharged later in the night when demand for power is down but power is still being generated by fixed output sources like coal, nuclear, and geothermal plants.
No one is forced to participate. If you want to make some cash you sign up for this. If you imagine even half of the electric cars participating in this program, you have a massive power storage grid. And there are more electric cars being built every day.
Second, the political barriers in the power grid involve power companies cooperating to maintain power availability. This isn't an insurmountable problem. This is really different from the political issues that surround the construction of nuclear plants.