ILLUMRA Wireless Battery-Free Light Sensors save time, energy, and money by avoiding costly and time-consuming installation of hardwired daylighting controls. The light sensor saves energy by lowering the output of artificial light when daylight is present in a room, saving up to 60 percent of the energy. The wireless sensor works in conjuction with wireless relays, dimmers, room and task on/off controllers and can integrate into systems using BACnet, RS-232, and Ethernet gateways. The sensor can be used in open-loop and closed-loop daylight-harvesting applications, is RoHS compliant, and may help buildings qualify for LEED credits and comply with International Green Construction Code Standard 189.1. When fully charged the sensor can work in total darkness for up to three days.