The STM 110 wireless sensor transmitter from EnOcean, Boston, MA, harvests and stores solar energy and measures incoming data with ultra-low-power electronics. The module requires neither line voltage nor batteries. Compatible with existing sensors and industry-standard networks, such as LON, Ethernet, group receivers, and central building controllers, the STM 110 can communicate with multiple receivers. A thin-layer solar cell requires 5 fc to generate electricity and an energy accumulator to store power for days. The radio has a 100 ft. indoor range through walls.