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Factors Affecting Solar Power Generation
- Dec 22, 2018 -

(1) Solar height angle

For a certain point of the earth, the solar elevation angle refers to the angle of intersection between the incident direction of the sunlight and the ground plane, that is, the angle between the solar ray of a certain place and the surface tangent perpendicular to the center of the earth, referred to as the solar height.


Since the Earth's atmosphere absorbs, reflects, and scatters solar radiation, the proportion of infrared, visible, and ultraviolet light in the light is also a function of the solar height angle. When the height angle of the sun is 90°, In the solar spectrum, infrared light accounts for 50%, visible light accounts for 46%, and ultraviolet light accounts for 4%. When the solar height is 5%, infrared rays account for 72%, visible light accounts for 28%, and ultraviolet light is close to O.


The height of the sun is constantly changing throughout the day, and it is constantly changing throughout the year. For a ground plane, when the sun's elevation angle is low, the light travels through the atmosphere for a long distance, the radiant energy is attenuated more, and at the same time, because the light is projected onto the ground plane at a small angle, There is less energy reaching the ground plane. On the contrary, it is more.


(2) Air quality

The amount of solar radiation is affected by the magnitude of the reduction, which is related to the length of the solar radiation passing through the atmosphere. The longer the distance, the more energy is lost; the shorter the distance, the less energy loss. The air quality is the dimensionless path of radiation passing through the atmosphere. It is defined as the path of sunlight through the atmosphere and the sun in the zenith. The ratio of the path to the ground when directiond. Let the path of vertical sunlight on the sea level be 1, that is, the dimensionless distance is m=1


(3) Atmospheric transparency

The solar irradiance is a constant on the plane perpendicular to the upper boundary of the atmosphere, but on the surface of the earth, the solar irradiance is constantly changing. This is mainly caused by the difference in the degree of transparency of the mountain atmosphere. Atmospheric brightness is a parameter that characterizes the extent to which the atmosphere transmits sunlight. In clear, cloudless weather, the atmosphere is highly transparent, and there is more solar radiation to reach the surface. When the sky is foggy and the sand is very dusty, the atmospheric transparency is very low, and the solar radiation energy reaching the ground is less. It can be seen that the degree of atmospheric trace is related to the amount of cloud in the sky and the amount of impurities such as dust contained in the atmosphere. In order to consider the influence of atmospheric transparency on solar radiation, after deriving from the complicated formula, it can be made into the following table to find the direct solar irradiance under different solar elevation angles and atmospheric transparency.