System and method for cleaning rows of solar panels. Each solar row has an upper edge elevated above ground level and a lower edge to provide an inclination of the solar row. A cleaning assembly cleans the solar panel surfaces. A support frame supports the cleaning assembly and enables upward and downward motion in the width and length directions of the solar row. Operation and movement of the cleaning assembly is controlled so as to clean a surface of the solar panels during downward movement. The cleaning assembly is preferably not operative during upward movement. During downward movement, the cleaning assembly removes dirt, debris and dust from the surface of the solar panels and generates an air stream to blow off the dirt, debris, and dust. The system further includes a guide system for moving the cleaning assembly to align with successive solar panel rows.