Method and apparatus for testing photovoltaic devices

The present invention generally relates to an apparatus used for simulating spectrum of solar radiation and testing a photovoltaic device using the simulated spectrum of solar radiation. In one embodiment, the apparatus includes a light-source device configured to reproducing spectrum of solar radiation, the light-source device comprising a radiation plate divided into a plurality of cells, and each of the cells comprises a plurality of light-emitting diodes emitting at least two different wavelengths, and a substrate support disposed opposite to the light-source device. In one example, the plurality of light-emitting diodes emit a wavelength that is selected from the group consisting of colors blue, green, yellow, red, a first and a second color in infrared having different wavelengths with respect to each other.