Effect of Solar Angles on Incident Energy of the Flat Collectors

In this paper the daily, monthly, seasonally, and yearly optimum slope angles of solar collectors are determined for areas in Iran and new models are developed to calculate the monthly, seasonally, and yearly optimum slope angles for latitudes of to north. To achieve this purpose, the slope and surface azimuth angles of solar collectors for receiving maximum solar radiation were determined in some Iranian cities in different days, months, seasons, and the whole year employing different models. According to the optimum slope angles predicted in this paper and using the optimum slope angles achieved by other researchers at locations out of Iran but in the same range of latitudes, the models are obtained. The outcome of this research is that the optimum slope angle of flat solar collectors has a linear relationship with the latitude of the site.