Have you ever been out somewhere at sunset and seen all of the outdoor lighting come one all at once? Most likely, the light fixtures were automated with photocells. Also called light sensors or photo controls, these sensors automatically turn your lights on at sunset and off at sunrise with no programing required.
Photo sensors can be used in practically any lighting application, whether residential or commercial. But how do you find the right one to pair with your fixtures? In this guide, we will cover everything you need to know about light sensors.
How do Light Sensors Work?
A light sensor is a device that operates by utilizing the working principle of the photoelectric effect. First fully explained by Albert Einstein in 1905, the photoelectric effect essentially boils down to this: light can be converted into energy.
Photocells use a light-dependent resistor (LDR) to work. If you’ve ever looked at one close up, it’s the part with the squiggly lines on it (see the image below). The resistor contains a semiconductor material, usually cadmium sulfide, that allows electrons to flow when the material is exposed to light. When light hits the photocell, the energy produced by the light excites the electrons into moving. This creates an electric current that shuts the light off.