Thin film is very light, but low power and very expensive.
Powerfilm makes some of the best folding or rollable thin film solar panels.
Powerfilm R28 rollable panel is
$285, 15V up to 1.8A. Unrolled size is 2.0m x 0.37m or 6.6' x 1.2'. Weight is 1.8 lbs.
A series configuration of 5 panels would probably be appropriate to charge a 65V battery like the 2012 Zero bikes. Cost is $1425, unrolled size 6.6' x 6.0', weight 9.0 lbs. Under direct sunlight you should expect to charge around 120W, which would give you about 1-1.5 miles of additional range per hour charging.
Here's an example monocrystalline (rigid) configuration.
Power Up BSP40-12 is
$132, 17V up to 2.4A. Size is 2.3' x 1.75', weight is 11.8 lbs.
A series configuration of 4 panels would be appropriate to charge a 65V battery like the 2012 Zero bikes. Panel cost is $528, rack size is 3.5' x 4.6', panel weight is 47 lbs. Under direct sunlight you should expect to charge around 156W, which gives you around 1.3 - 2.0 miles of additional range per hour charging.
A multi-point power tracking controller could boost charging power by 10-20% .. but good luck finding one designed for the lithium batteries in our bikes.