The solar arrays  are one of the most promising renewable energy technologies for providing energy needs . in buildings. For installed solar panels on building roofs, knowing the optimal inclination angle is important in order to obtain the maximum annual or seasonal energy. In fact, the changes in slope angle affect the amount of solar radiation that reaches the surface of the panel. In this study,  various models were used to obtain optimal tilt angle and azimuth angle in solar panels installed angle in Mashhad. Using ayzrvtrvpyk isotropic model, the optimal angles for various months, seasons of the year were deterimend. Also,  panels’ optimal slope and azimuth angles in Mashhad were calculated and determined using non-isotropic model. In general, the total annual energy achieved by panels equipped with a single axis  and dual axis sun tracking system  could increase by 16%  and 30%, respectively, compared to what achieved by fixed angle solar panels.