We propose a very simple system to be adapted to a Fourier Transform Infra-Red (FTIR) spectrometer with which three different types of characterizations can be done: the Fourier transform photocurrent spectroscopy, the recording of reflection-transmission spectra of thin film semiconductors, and the acquisition of spectral responses of solar cells. In addition to gather three techniques into a single apparatus, this FTIR-based system also significantly reduces the recording time and largely improves the resolution of the measured spectra compared to standard equipments.