Ultra Violet rays from the sun.
Electromagnetic...meaning light rays, primarily in the visible spectrum. Ultraviolet and infrared light rays actually degrade most types of solar panels, limiting their useful lifetime. That said, your question is not stated well...so I'm not sure if that's the information you were looking for. Rays are not used in solar panels...rather solar panels are used to collect sunlight and convert it to energy--either directly into heat in the case of passive solar, or into electricity by the use of photovoltaic cells.
