Two-photon excitation spectra of photo-voltaic effects and relevant excitonic emissions of a naturally grown single crystal of Cu2O have been studied at 77 K and 2 K. The photo-voltaic effects have been detected under local excitation at a macroscopical distance apart from the electrodes. The participation of the yellow series excitons in the generation of the photo-voltaic signal has been discussed. © 1998 American Institute of Physics.