This paper describes the design process and implementation of a two-axis sun tracker prototype for solar modules positioning by sensing the point of maximum brightness of the sky with the building of a sensor based on a geodesic dome and using a structure motion on horizontal celestial coordinates. The developed prototype system performs a continuous sampling of the entire sky; allowing it to identify the brightest point of the firmament, even with a partly cloudy sky, and guiding the solar module to that point by using a two-axis drive system, and running a new sampling of the sky every five minutes to reposition the solar module if the brightest point has changed its location. This sun tracker system uses as sensor element a Light Dependent Resistor (LDR) or a photoresistor to find the brightest point in the sky. The data and signal processing of the lightning sensor (using LDR matrix) and solar modules are performed by a microcontroller-based system. The energy obtained from the solar module is bigger and remains stable when the two-axis sun tracker prototype is used.