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Optimal Site Selection for a Solar Power Plant
Primary energy sources are running out due to the increase in electrical energy consumption. Environmental problems caused by primary energy sources are also increasing.
This Solar Irradiance reaches the surface of the earth in two forms, beam radiation (Gb) and diffuse radiation (Gd). The beam component comes directly as irradiance from the sun, while the diffuse component reaches the earth indirectly and is scattered or reflected from the atmosphere or cloud cover.
The total irradiance received on a surface is sum of both the radiations i.e. G(total) = Gb + Gd (beam and diffuse)
Irradiance is a measurement of solar power density and is defined as the rate at which solar energy falls onto a surface. The unit of power is the Watt (abbreviated as W). In the case of solar irradiance we usually measure the power per unit area, so irradiance is typically quoted as W/m² - that is Watts per square meter. The Irradiance falling on a surface can be vary from moment to moment which is why it is important to remember that irradiance is a measure of power density - the rate that energy is falling on an area, not the total amount of energy per area.
Peak Sun Hours (PSH)
Peak Sun Hours (PSH) : the total number of hours per day in which solar irradiance averages 1000 w/m².
The amount of solar radiation, or insolation, delivered by the sun varies throughout the day, based on the sun’s position in the sky, clouds, and other atmospheric conditions.
1. Time of Day: Peak solar radiation occurs at solar noon, when the sun is highest in the sky. The low angle of the sun at sunrise and sunset means that the atmosphere filters the sunlight more and results in less energy being delivered to the earth’s surface.
2. Season: Sun-hours increase during the summer due to the sun’s higher position in the sky.
3. Geography: Solar energy increases near the equator, as it is closer to the sun.
Irradiance : the intensity of solar power measured in watts or kW on one square meter. Irradiance is measured with the instruments is called as Pyranometer.