Solar radiation will be involved in the application of solar panel # solar energy #. Let’s briefly explain today. Solar radiation, commonly referred to as solar energy resources or simply sunlight, is the general term for electromagnetic radiation emitted by the sun. Various technologies can be used to capture solar radiation and convert it into useful forms of energy, such as thermal and electrical energy. However, the technical feasibility and economic operation of these technologies in a particular location depends on the available solar energy resources.
basic principle
Every place on Earth receives sunlight at least for part of the year. The amount of solar radiation reaching any point on the Earth’s surface varies depending on the following factors:
geographical position
Time of day
season
Local landscape
Local weather
Because the Earth is round, the sun shines on the Earth’s surface at different angles, ranging from 0 ° (just above the horizon) to 90 ° (directly above the head). When the sun’s rays are perpendicular, the earth’s surface receives all possible energy. The more tilted the sun’s rays, the longer they travel through the atmosphere, becoming more diffuse and diffuse. “Because the Earth is round, cold polar regions never experience high sunlight, and because the axis of rotation is tilted, these regions do not see sunlight at all for some time of the year.”.
The Earth rotates around the sun in an elliptical orbit, and is closer to the sun during part of the year. The closer the sun is to the earth, the more solar energy is received on the earth’s surface. The Earth is closest to the sun in summer in the southern hemisphere and winter in the northern hemisphere. However, due to this difference, the presence of vast oceans mitigates the hotter summers and colder winters that people expect to see in the southern hemisphere.
The 23.5 ° inclination of the Earth’s rotational axis is a more important factor in determining the amount of sunlight that illuminates the Earth at a particular location. The tilt causes the northern hemisphere to have longer days from the vernal equinox to the autumnal equinox, while the southern hemisphere has longer days for the other six months. Before and after March 23 and September 22 each year, the day and night at the equinox are exactly 12 hours.
Midlatitude countries such as the United States receive more solar energy in summer, not only because the days are longer, but also because the sun is almost overhead. In the shorter days of winter, the sun’s rays are more inclined. Cities such as Denver, Colorado (with a latitude close to 40 degrees), receive almost three times as much solar energy in June as in December.
The rotation of the earth is also responsible for the hourly changes in sunlight. In the morning and evening, the sun is low in the sky. When the sun is at its highest point, its light travels farther through the atmosphere than at noon. On sunny days, the maximum amount of solar energy reaches the solar collector around noon.
Diffuse and direct solar radiation
As sunlight passes through the atmosphere, some of it is absorbed, scattered, and reflected:
Air molecules
steam
cloud
dust
Contaminants
forest fire
volcano.
This is called diffuse solar radiation. The solar radiation that reaches the surface of the Earth without diffusion is called direct beam solar radiation. The sum of diffuse and direct solar radiation is called global solar radiation. Atmospheric conditions can reduce direct beam radiation by 10% on sunny, dry days, and by 100% on dense, cloudy days.
measure
Scientists measure the amount of sunlight that falls at specific locations at different times of the year. Then, they estimate the amount of sunlight falling in areas of the same latitude and similar climate. The measurement of solar energy is usually expressed as total radiation on a horizontal surface, or tracking the total radiation on the surface of the sun.
The radiation data for solar power generation (photovoltaic) systems is typically expressed in kilowatt hours per square meter (kWh/m2). A direct estimate of solar energy can also be expressed in watts per square meter (W/m2). Radiation data for solar hot water and space heating systems are typically expressed in British thermal units per square foot (Btu/ft ²) express.
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