That's the biggest problem with electrics - if everyone has one, then each of those need to be charged. Solar and Wind are not 100% of the time, and have relatively small outputs for their size. All of a sudden you're consuming a lot of power, all at once (most are going to charge while at home, maybe at work.) The already sagging grid would probably be unable to handle the power consumed, assuming renewables could even provide the necessary power - on top of power already consumed by the average household.