A light emitting apparatus comprises a light source array, a diffuser, and a control module. The diffuser is located below the light source for providing the simulated solar light to a test plane. The control module is configured for controlling driving voltages of the light source array. The emission spectrum of the light emitting apparatus complies with a predetermined standard, and the light source array is divided into a plurality of light groups with different wavelength bands according to the predetermined standard. The light groups in the light source array are composed of a plurality of light rows connected in parallel, and each light row of the light group is composed of a plurality of light emitting diodes (LEDs) and a resistor connected in series.