Estimating Solar Radiation and Developing Iran’s Atlas Map of Optimum Monthly Tilt Angle (TECHNICAL NOTE)

Iran has great potential in utilizing solar energy. In order to maximize the amount of absorbed solar radiation to absorber surfaces, the surfaces should be installed at a suitable angle slope to the horizon that is discussed in this article. The calculations performed in this study was done using MATLAB software. In this study, radiation received on the ground in 31 provincial capitals of the country for 12 months of the year has been modeled. Then, the optimum tilt angle of absorbent surfaces with the maximum amount of radiation received on the surfaces of the absorber is estimated. Finally, after validating the results, using available software in the field of GIS, atlas map of optimum tilt angle with respect to the horizon for the installation of solar absorber surfaces and amount of absorbed solar radiation on surface mounted in the optimum tilt angle for Iran was presented for 12 months. It is observed that optimum tilt angle varies throughout the year between -10 to 62 degrees. The minimum value of optimum tilt angle in different months is related to North West provinces. The lowest amount of solar radiation is received on Caspian littoral, and its value varies between 9 and 19 MJ per square meter per day for different months. The highest amount of radiation in region of the provinces Yazd and Isfahan is received and its value varies between 19 to 31 MJ per square meter per day for different months. The figures presented in this paper eliminate the need for estimating clearness index, optimum tilt angle, and corresponding solar radiation in cities and regions on which no information is available. It provides researchers with the aforementioned values based on the mean of values of adjacent regions.