SOLAR POWERED RADIO FREQUENCY TRANSMITTER

An assembly includes a solar cell to convert light into electric power, a radio frequency (RF) transmitter to convert electric power from the solar cell to RF energy and transmit the RF energy, and a mounting interface to mount the assembly to a window or transparent surface, wherein the solar cell is oriented to receive the light through the window or transparent surface. The transmitted RF energy may be adequate to power one or more RF self-powered devices and/or may include light level information. The light level information may include a measure of the light entering through the window and/or available light in a space of the building. The light level information may be implemented as an ON/OFF signal or a measure of the light level.