any plans? sounds extremely interesting especially when combining with solar to be able to store the energy in the car and use later... :-)
I suspect the problem is that Tesla wants to maintain very precise control over the battery usage, in order to maximize the life of the battery. Once you start using external systems to draw power from the car, that level of control is impossible.
It's also a profoundly silly idea. I would buy a car that can barley get to work and back, and then plug it into an office building which will drain it during the DAYTIME? That's going to be great when it's time to go home.... And I'm going to use my charge/discharge cycles for this? Not.
Vehicle to building will be the future for peak shaving especially when combined with PV and such. Distributed grid is a real possibility short term. Tesla won't do it in the S (it's explicitly outlawed in the warranty) but by GenIII watch out.
Aren't there also significant losses due to inefficiencies on both the charging and discharging sides?
A good rule of thumb for charging efficiency is about 85% (15% loss). In other words, you have to draw 11.5 kWh off the grid in order to add 10 kWh to your battery charge. I don't have an estimate for inverting power back onto the grid. But when it's inverted to drive an EV motor, the efficiency is really good, in the range of 97-98%.
Tesla is making battery packs for First Solar for home energy storage off the grid. They are in pilot phase now. I was thinking the same thing about the car. It would be nice in emergency situations at home to be able to power your house with the huge battery pack in the car during an electrical outage.
I asked JB Straubel about his and he claims there are no plans except for the Solar City battery backup.
Much to my disappointment.
This is an emergency only solution, so Leaf owner certainly gets free ride to home and back.
Car could still maintain control of battery usage. If overused it could simply cut power.
V2G is an important part of our energy saving future. Local energy storage plays a key roll in leveling the load on the grid, which will become even more important when there are more BEVs and PHEVs around combined with increasing local energy production (solar, wind, ...).