Solar Radiation Geometry – Different Parameters | New Topic [2024]

In this note, we are going to learn about the Solar Radiation Geometry and about its different parameters. Welcome to Poly Notes Hub, a leading destination for polytechnic notes for diploma engineering students.

Author Name: Arun Paul.

What is Solar Radiation Geometry?

Solar Radiation Geometry describes the spatial connections and angles involved in the interaction of solar radiation from the sun with the Earth’s surface. It takes into account a variety of parameters, including the sun’s position in the sky, the orientation and tilt of surfaces receiving sunlight, and the observer’s geographical location.

Some important key aspects of solar radiation geometry –

• Solar Position: The sun’s position in the sky changes during the day and season due to the Earth’s rotation and orbit.
• Solar Angles: Measures such as zenith, elevation, and azimuth angles define the sun’s location relative to an observer, influencing solar exposure.
• Surface Orientation and Tilt: The orientation and tilt of surfaces, such as solar panels, affects sunlight reception. The azimuth and slope angles describe this orientation.
• Geographical Location: Latitude and longitude define a location’s position relative to the equator and Prime Meridian, which influences solar radiation incidence and day length.

Parameters of Solar Radiation Geometry

Below we listed some solar radiation geometry parameters –

1. Latitude: Latitude is the angular distance between a position north and south of the Earth’s equator, measured in degrees. It specifies the location’s relative position to the equator and the angle at which solar radiation impacts the Earth’s surface. Higher latitudes receive less direct sunlight than lower latitudes.
2. Longitude: Longitude is a location’s angular distance east or west of the Prime Meridian, which passes through Greenwich, England. It is also measurable in degrees. Longitude helps to identify a location’s position relative to the Earth’s rotation and is used in conjunction with latitude to calculate local time.
3. Declination: Declination is the angle formed between the sun’s beams and the plane of the Earth’s equator. It varies throughout the year due to the tilt of the Earth’s axis and the planet’s orbit around the Sun. Declination is zero during the equinoxes, reaching its highest positive value at the summer solstice, and its maximum negative value at the winter solstice.
4. Surface Azimuth Angle: Surface azimuth angle, often called orientation angle or azimuth angle, is the angle between a surface’s orientation and true south (in the Northern Hemisphere) or true north (in the Southern Hemisphere). It indicates how a surface is inclined horizontally.
5. Solar Azimuth Angle: The solar azimuth angle is the angle, measured clockwise from the south, between the direction of the sun and true north (in the southern hemisphere) or true south (in the northern hemisphere). It shows how the sun appears in the sky with relation to the observer’s position.
6. Slope of Surface: The angle at which a surface is tilted with respect to the horizontal plane is called its slope. It controls the efficiency of solar energy capture and how directly solar radiation reaches the surface.
7. Hour Angle: The hour angle is the sun’s angular separation, expressed in degrees, from the local meridian, either eastward or westward. It shows the time of day in relation to solar noon; morning hours are shown by negative values, and afternoon hours are indicated by positive values.
8. Angle of Incidence: The angle formed by the direction of incoming solar radiation and the normal, or perpendicular, to the surface that is receiving it, is known as the angle of incidence. It is influenced by the surface’s orientation, the sun’s location in the sky, and the surface’s slope.