THE ASSESSMENT OF OPTIMAL TILTING ANGLE OF FLAT PLATE SOLAR COLLECTORS - CASE STUDY FOR RAFSANJAN, IRAN

One of the important parameters that affect the performance of a solar collector is its tilt angle with the horizon. This is because the variation of tilt angle changes the amount of solar radiation reaching the collector surface. In the present study, the monthly average daily diffuse solar radiation on a horizontal surface was initially computed and then a standard isotropic model was exploited for estimation of the global solar radiation on inclined surfaces. Finally, the monthly, seasonal, and yearly optimum slope angles were proposed for the maximum global solar radiation. It was found that the monthly optimum tilt angle varies from 0° (May and July) to 62.3° (December), besides, the seasonal optimum slope angle is between 5.1° (spring) to 54.8° (autumn) and the optimum yearly tilt angle is 29.9° which is close to the latitude of Rafsanjan, Iran.