In this paper, we present a SOI CMOS Ultra-Low-Power (ULP) three-stage charge pump designed to interface photovoltaic (PV) cells co-integrated in the SOI substrate and used as a DC power source. Under an irradiance of 100W/m2, 2 PV cells in series provide a 815mV open-circuit voltage and a 21µA short-circuit current. Indoor measurements have been realized connecting them to one charge pump and the obtained output voltages of both the solar cells and charge pump vs. load are discussed. Improvements and perspectives are provided for an irradiance of 500W/m2. Co-integration is realized on a 2µm multiple-threshold voltage SOI CMOS technology for ULP applications.