Storage has always been the problem with renewables. Seems great strides are being made with salt based batteries though.
One thing I don't understand with EV's is why they don't chuck alternators on the wheels, or have an extra jockey type wheel with an alternator attached so batteries get charged as soon as you start moving? You would think there would be an optimum speed where no power is being drained from the batteries ie power being used equates power being generated. Could also use air scoops so power is generated by use of "wind" as you are moving. I suspect if they are made too efficient, some twat won't make enough money from recharging stations which gain their power from fossil fuels anyway (unless in your area there is nuclear power available).
They are the future though but as you say, haven't got it worked out yet.