The big story here is, this is yet another example of a company realizing that putting up Solar PVs in parking lots makes a ton of sense. The observant will recall the recent deal with the Redskins/FedEx in which premium spots at the FedEx field will be shaded by PVs.
You have electrical infrastructure at hand that you can readily tie into, and as a big bonus the PVs create shade for the cars beneath them. This may not be a big deal for gas powered cars but for EVs it is a very big deal.
Your car is cooler so it requires less power to cool when you get in, and also don't forget that cars with liquid cooling for the battery will actually run the cooling loop while the car is parked, if battery is in a high state of charge, and the temperature is very high, say over 110f. This it does to preserve the life of the battery.
In the Volt it will do this until the battery drops to a 50% state of charge.
Also, I imagine the thinking at GM is "nothing dispels the you are only moving pollution from the tailpipe to the smokestack myth like have a solar powered canopy charge the car at the dealer. Ha! In your face Rush Limbaugh Zombies!"
http://www.freep.com/article/20110729/B ... lar-panel-