Photoelectric Cell See also: Photovoltaic Cell Also called photocell, a device whose electrical characteristics (e.g., Current, Voltage, or Resistance) vary when Light is incident upon it. Common photoelectric cells consist of two Electrodes separated by a light-sensitive Semiconductor material. A Battery or other voltage source connected to the two electrodes sets up a current even in the absence of light; when light strikes the semiconductor section of the photocell, the current increases in proportion to the light intensity. Photocells can be used to operate Switch, Relays, door openers, and intrusion alarms.