WOW, what a load of baloney!
The device shown had a diameter of about 4 inches. For the sake of argument, let's pretend that that 4 inches are ALL solar cell. The area of a 4 inch circle is 12.5664 sq ins., which is 8.75% of one square foot.
The estimated maximum energy delivered to the surface of the earth by the sun is 600 watts per square meter. One square meter equals 10.764 square feet, so one square foot would receive 55.741 watts, and therefore this device would receive a maximum of 4.87 watts of energy per day. The best commercially available photovoltaic panels can achieve an effiiency of 21%. So under THE BEST conditions with THE BEST materials, this little window sticker could output 1.0227 watts per day.
Such a device would be nearly useless and is probably a scam aimed at the innumerate.