The invention relates to an obstacle shadow shielding calculation method on different roof conditions. On the basis of information including a
slope angle an
azimuth angle of a roof, an obstacle height, a sun
azimuth, and a sun elevating angle of a roof, projection of an obstacle on the roof is determined and components of the projection in a north-south direction and an east-west direction of theroof; and according to information of the
slope angle and the orientation of the roof, components of the obstacle in all directions of the roof are calculated precisely at any time, thereby providingthe important in parameters for the refined design of the
photovoltaic power station. Compared with the traditional industrial way of determining the shielding range only based on the experience, theobstacle shadow shielding calculation method has the following advantages: the shadow shielding range of an obstacle on a horizontal plane in any
time range can be calculated and the shadow shieldingrange of the roof obstacle any an azimuthal angle and a gradient angle in any
time range can be calculated, so that the refined design of the
photovoltaic system is guided well.