In this paper, EnOcean presents their radio sensor module STM 110 in more detail. The module obtains its operating energy from a small solar cell. Like its predecessor, the STM 100, the STM 110 sensor module was designed as a maintenance-free radio module to transmit various sensor information. It can be powered by the solar cell that comes with it and which measures just 13mm x 35mm. An integrated energy store enables the module to function fully, even after several days of total darkness.