I’d be thrilled if the first or second generation of the Volt just had smart charging! Step one is just to have the capacity to charge when power costs the least to produce (and it would help if utilities charged accordingly). Even a timer would be fine but a more ideal circumstance would have two way communication with the utility such that my vehicle was fully charged before I needed it but done at the most off-peak period as much as possible, rather than putting in much of the charge as soon as I plug it in when I get home (which is still peak hours).

To discuss V2G when we do not yet even have the capacity to have smart G2V is premature.

In some areas the cost of solar for DIY is already at only a little above $1 / watt.

My utility will rebate $3.50/w.
My state (NY) will tax credit 25% of remainder.
Fed will kick in another $2000 in tax credits (30% limited to $2K).

For a DIY (self install) system the cost is about $5.50/w.

Not all utilities will rebate for DIY.
When the material cost is down to $2/w, the utilities won’t give significant rebates, it would make more sense for them, where they have land available to install solar farms themselves, where their install cost is much much lower.

So for DIY solar CURRENTLY the end cost is between $1.50 and $1.00 /w plus time and effort. If you live in an area with generous rebates.

Professional residential installers charge a handsome $2 on top of this.

Now out of about 7,000,000 people serviced by my utility, there are only about 1100 solar installations. So maybe very generously 0.05% of potential buildings with a good exposure.

What does this tell you about human nature?

Another technical problem with placing solar paint or panels on a car is that photovoltaic systems work best when aligned in a single plane. This is because solar cells are constant current devices wired in series (to get enough voltage). The current through the cells is proportional to the amount of sunlight hitting the cells. A consequence of this is that the total current is limited by the cell with least light on it.

There are ways to reduce this effect, but the effect of the current being controlled by the single cell with the least light on it is important and can easily cause a 80% drop off in power.

Thus covering the roof and bonnet in cells / paint has some merit. But covering other areas could actually cause less output not more.

Solutions used in PV systems are strings (x cells in series, and y in parallel), and bypass diodes (actually to protect cells more than reduce this effect).

If the cells can be printed to be small, then there is more potential to using in different planes (e.g. sides of car). Using many more strings. For silicon smaller cells increases cost too much.

According to GM, for the Volt, “V2G won’t be possible, but future versions may very well have these capacities”. See here for details:
http://www.gm-volt.com/2007/11/27/your-questions-answered-by-top-chevy-volt-executives-part-6/

Note that adding V2G capability is not trivial. Electric current doesn’t just magically flow back and forth between a 300 volt DC battery and a 110v or 220v AC grid connection. There is electronic circuitry involved. Converting 110v or 220v AC to electrical pulses that will charge a DC battery is fairly simple and cheap.

Converting 300v DC battery voltage to an AC sine wave that synchronizes exactly with the grid is much more complicated an expensive. There are also safety issues. For example, what if an electric line goes down and you have a live wire on the street? The electric utility will turn off power to that line and then send in a repairman. But if V2G is connected to that line, the wire may still be live, so the DC to AC circuit needs to be smart about this as well.

For an example of whats involved to convert DC to grid compatible AC, here is a popular unit for home solar systems:
http://www.affordable-solar.com/xantrex-gt-28-inverter.grid.intertie.htm
This is the smallest unit in this particular series, supplies about 12 amps at 220v, and implements all necessary safety features. Cost is just under $2000.

And by the way, V2G will require 220v connections, which means paying an electrician to install a special outlet and buying a special 220v outdoor extension cable, neither of which is cheap. In addition, 110v charging over 6.5 hours at night is perfect for the grid. 3 hour 220v charging would probably shift that profile from the night more toward the evening, so this could actually do more to overload the grid than help it.

I’m not saying we should abandon research on V2G, but with the issues involved, I don’t think we should rush into it either.

I thought V2G was also a crap idea but there was a link here a few days ago to a story that said that there are occasional 30-60 spikes in grid usage and if EV batteries could be used to address these short spikes, power plants could be much more efficient. So if V2G just means occasionally selling the electric company 60 seconds worth of battery power, why not.