Determination of optimum location and tilt angle of solar collector on the roof of buildings with regard to shadow of adjacent neighbors

Solar systems have been widely used in recent years to supply some portion of buildings energy demands. Solar cells and flat collectors usually installed on the roof of buildings to keep away from the shade effects. Moreover, those must be installed incline at optimum angle to maximize the receiving energy. Determination of the optimum tilt angle of solar collectors is the subject of many investigations. These studies had supposed that, there is no barrier between the sun and collectors from sunrise since to sunset. In fact, any building may be surrounded by taller neighboring buildings. In these conditions, previous studies could not estimate the optimum tilt angle, truly. In addition, there are locations on the roofs which have more sunny time. These areas are more suitable for installation of collectors. Determination of optimum location and optimum tilt angle of solar collectors on the roof, with respect to the shadow of adjacent buildings is the main aim of this paper. Obtained results revealed that for earth's northern hemisphere, solar collectors should be installed on the southern edge of the roof as far as possible away from the taller neighboring building. If the roof is surrounded by two taller buildings, solar collector should be installed approximately on the center of the southern edge. Accordingly, received energy form the direct solar radiation on the optimum location could be increases more over the 15%. In addition, it was found that shade has minor effects on the optimum tilt angle for the parts of the roof near to the taller neighbor. In contrast, there is a considerable change of optimum tilt angle (up to 10°) for the farther regions form the taller neighbor.