The performance of the system of the solar radiation conversion is influenced via the angle of tilt with a horizontal plane; therefore, the photovoltaic array requires to be tilted at the right angle for maximizing the system conversion efficiency. The present paper has been carried out monthly at the optimum tilt angle numerically with an experimental system set up for home supply in Baghdad city (latitude 33°20'). Mathematical models were programmed by MATLAB to predict the solar energy incident on the surface all day of the year at angles from (0-90°). Experimental results manifested the performance of photovoltaic panel (PV) to provide a home with a light energy use in the shortcut electricity. The solar power system output is a function of the solar radiation. The high output of power was between (11.00 am) and (1.00 pm), which matches the high-power output time. The monthly optimum tilt angle can vary significantly during the year between 18° in summer to 65° in winter season.