I think the evening (non peak) hours for charging would be the best bet. Plugging it in during the day in the summer during peak would be much more expensive for sure. They have a dealership near me in Washington D.C., I was sitting at a traffic light last night right in front of it. It was really cool - I think I'm going to go for a visit and check it out sometime soon.

I'm a big fan of electric (not hybrid) vehicles and would consider one in the future.