Abstract: A sign board lighting assembly is provided and includes a pair of solar powered lighting modules positionally opposed at front and rear sides of a sign bar adapted by hardware to hang the sign board, each lighting module including a housing supporting a solar collection array, an energy storage medium, an illumination grid, connected together by electrical trace or wire, and an optical switching element connected to the tracing or wiring between the energy storage medium and the illumination grid, the optical switching element operable according to an optically detected threshold level of ambient natural light to open and to close a circuit in the tracing or wiring between the energy storage medium and the illumination grid.