A light source assembly employed in a projector includes a light source, a power device, a light energy storage device, and a selection switch. The light source is configured for providing light beams for the projector. The selection switch is electrically connected to the light source, the light energy storage device and the power device and is configured for selecting one of the light energy storage device and the power device to provide power for the light source. The light energy storage device can absorb heat from the light source and convert the heat into electricity. Therefore, energy is saved and heat produced by the light source is reduced via the light energy storage device compared to the conventional light source assembly.