A solar powered smart window includes a light diffuser configured to convert an incident direct solar radiation to a diffusive light toward interior direction, a light diffuser positioner, a driving mechanism, a solar panel, and a control unit. The control unit moved the light diffuser from a predetermined opened position to a closed position and to hold the light diffuser at the closed position with latch mechanism, when the output power of the solar panel exceeds a threshold for over a duration time. The controller releases the latch mechanism and to cause the light diffuser to return to the predetermined opened position when the output power lowers below threshold for over the duration time. A method includes storing a predetermined condition, monitoring the output power, comparing the output power with the predetermined conditions, making decision whether a positional transition is necessary, and causing the transitional transition or maintaining current position.