The Solar Man folding electric bike with a solar charged battery weighs only about 26 lbs.
The battery, which can be charged through built in photovoltaic cells or line power, is the blue strip down near the crank. I can't figure out where the motor is -- maybe it's in the bulk around the crank and apparently drives the crank instead of the wheel, unlike most eBike designs.
More about this design from International Council of Societies of Industrial Design. Hat tip to "William" who directed me to this design blog.