As I understand, vehicle-to-grid technology is about using the battery of your electric car to give electricity for the microgrid. How would this be useful as we are just moving electricity from place to another, and the battery of the car will need to be recharged?
Moving electricity from one place to another sounds pointless if you omit the purpose, which is to provide power where it is needed from a location where it is not.
Consider for example these points on the Wikipedia page about vehicle-to-grid:
- A hybrid or Fuel cell vehicle, which generates power from storable fuel, uses its generator to produce power for a utility at peak electricity usage times. Here the vehicles serve as a distributed generation system, producing power from conventional fossil fuels, biofuels or hydrogen.
- A battery-powered or plug-in hybrid vehicle which uses its excess rechargeable battery capacity to provide power to the electric grid in response to peak load demands. These vehicles can then be recharged during off-peak hours at cheaper rates while helping to absorb excess night time generation. Here the vehicles serve as a distributed battery storage system to buffer power.
- A solar vehicle which uses its excess charging capacity to provide power to the electric grid when the battery is fully charged. Here the vehicle effectively becomes a small renewable energy power station. Such systems have been in use since the 1990s and are routinely used in the case of large vehicles, especially solar-powered boats.
The whole purpose is to put power back into the grid where it can be used, instead of just wasted (or not realized).
Consider a simple example: A solar panel on a vehicle that is not in use and fully charged, is being underutilized. If your neighbor has just returned from a drive, power that your panel produces can be sold back to the utility and delivered to the neighbor.