Very light, pun intended. The clear part of the panel itself is plastic rather than glass, which is good for security when hanging from a suction cup hook on a window, and safety if it should be knocked down by a cat playing with a USB cord or something. >.> _____ >^.,.^<
It works most of the time, according to the weather and availability of sun.
It's real mission in life is the charging of cellphones (I recommend one panel per cellphone you need to keep charged), but I have plugged in a USB-compatible AA/AAA battery charger, and given time it works for that too.
I ordered two more panels before they sold out, and gave them to friends.