This article addresses a design and implementation of sun sensor for the attitude determination system of a nanosatellite. The purpose of the sun sensor is a determination of the coordonnees of the satellite-sun vector in the reference frame attached to the satellite. This is done by processing the photovoltaic signals issued from the solar sensors placed on the 6 sides of the satellite. The article presents a mathematical model of the sensor, the characteristics of the chosen solar panels, the methodology of calibration and details of the hardware and software implementation. The operability of the system is validated by a laboratory experiment, whose methodology is presented in details. The proposed algorithm of the sun sensor addresses the processing of the Earth albedo and the self-calibration aspects.