A system for measuring a characteristic of a solar cell is disclosed and includes a light source irradiating an optical signal having a spectral range from about 100 nm to about 3000 nm, a wavelength selector configured to selectively narrow the spectral range of the optical signal, a beam splitter, a reference detector in optical communication with the beam splitter and configured to measure a characteristic of the optical signal, a specimen irradiated with the optical signal, a reflectance detector in optical communication with the specimen via the beam splitter and configured to measure an optical characteristic of the optical signal reflected by the specimen, a multiplexer in communication with at least one of the reference detector, specimen, and reflectance detector, and a processor in communication with at least one of the reference detector, specimen, and reflectance detector via the multiplexer and configured to calculate at least one characteristic of the specimen.