Global Radiation

We will look at solar radiation and its use in the field of alternative energies. When you choose a solar hot water system, it is important to understand the difference between direct and global radiation.This is important because the solar concentrators, as the SolarBeam depend on direct solar radiation for energy, while the flat panels are based on global radiation, which is a more diffuse energy. To see if the direct radiation is much higher in your area, visit this link: direct, diffuse and global radiation radiation that falls on a surface directly from the Sun, without suffering changes of direction, is known as direct radiation, but all that solar radiation that arrives after being reflected or even infrared radiation emitted by molecules after suffering overheating by effect of absorption of solar radiation, is known as diffuse radiation. So that solar radiation at ground level will consist of a direct component, because it reaches us without suffering deviations, and other diffuse, disseminated via the celestial hemisphere, might seem apparently that this is who radiates it. The sum of these two components in a horizontal plane is called global radiation clouds spread or scattering solar radiation more better than air, so on a cloudy day all the radiation that we obtain will be diffuse radiation.

On a clear day the direct radiation is several times higher than the diffuse. The solar radiation that reaches a plane located at the Earth’s surface varies from one day, variation that is due mainly to the change in cloud cover. To give an indicative figure, on cloudy days when the solar radiation received by the surface is, for the most part, diffuse, the value of this radiation is usually much smaller in Kwh/m, While on a day sunny radiation value is much higher in Kwh/m. This will vary depending on the time of day, geographic area and season of the year. Why direct radiation is that more thermal solar energy transmitted and which can best be exploited. We also need to take into account the time variation of solar radiation received by a horizontal plane located above the Earth’s surface is due, primarily, to the movement of the Earth’s rotation.

To represent the movement of rotation we employ the hour angle. The hour angle measures the distance, expressed in degrees, between the flat meridian of Earth containing the Sun, which has an observer whose time we want to determine. The thickness of the atmospheric layer which must pass through the radiation to reach the surface varies throughout the day by the movement of rotation, so that, while this layer is thick to first thing in the morning, at noon (solar angle equal to 0 ) the thickness is minimal and, consequently, the solar radiation received is maximum. This is why all solar thermal systems can produce energy thanks to direct radiation, since radiation diffuse or global does not provide enough power to operate the equipment properly, or generate the energy needed, thanks to the direct radiation and high technology can be leveraged this solar thermal energy. As an example we have a technology based company that has designed a team called solarbeam, its features are first that it is a team of thermal solar concentration that directs all the direct radiation in a single focal point by concentrating all power at that point. This team also has a solar tracking system of dual-axis, which allows you to track the Sun throughout the day being able to harvest more energy. ESi wants to have more information about the use of thermal solar energy visit