Here's an idea for making the Nissan Leaf (or other EV) a solar vehicle.
A 8' x 20' solar panel placed above the Leaf could produce up to 2kW off of electricity, provided the panel could be tilted into the Sun. Now if that array also had two more 8' x 20' panels that slid out to the sides, making one large 24' x 20' solar array, it could produce up to 6kW using average PV cells.
It would have to be make as thin as possible, and have a curve that matches the airflow over the Leaf, without loosing structural integrity in high winds. It would also have to tilt, further adding mechanical stress to the whole thing.
Also the system would have to be integrated into the Leaf's electrical system somehow. One idea would be to make the top panel 400V and just hook it directly to the Leaf's main bus while driving. Then divide the voltages into 48V on all the panels and use an inverter to provide 240V power to the onboard charger when stopped. The system would have to be able to adjust the current of the charger to match the output of the solar array.