>When they talk about "sun rays", do they mean the UV portion of sunlight? I don't think so, because they say they use a standard monocrystalline siicon PV cel

>When they talk about "sun rays", do they mean the UV portion of sunlight? I don't think so, because they say they use a standard monocrystalline siicon PV cell -- which are (generally) crappy for UV scavenging. I would guess the material atop the solar cell is either slightly porous or made of a material that is mostly transparent to the right spectra of light, resulting in acceptable losses.