Glossary of Solar Radiation Resource Terms

Other relevant glossaries


The following links allow you to move to the words beginning with that letter.

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Gigawatt - 1,000,000,000 (or 109) Watts. This unit rose to public prominence in the 1985 motion picture Back to the Future in which 1.21 gigawatts of power were required for the time-travelling vehicle.


Global Horizontal Radiation - also called Global Horizontal Irradiance; total solar radiation; the sum of Direct Normal Irradiance (DNI), Diffuse Horizontal Irradiance (DHI), and ground-reflected radiation; however, because ground reflected radiation is usually insignificant compared to direct and diffuse, for all practical purposes global radiation is said to be the sum of direct and diffuse radiation only:

      GHI = DHI + DNI * cos (Z)

  where

      Z is the solar zenith angle.

Click Shining On (Figure 3) to see solar components


Greenhouse Effect - the warming of the Earth by the atmosphere because of water vapor and gases such as carbon dioxide, which absorb and emit infrared radiation, or heat. Thus, the high-energy photons such as light and ultraviolet radiation are passed through the atmosphere to the Earth, which tends to absorb them and emit lower-energy photons which are then captured in the atmosphere and partially sent back to Earth. As the presence of infrared absorbers rises in the atmosphere, the more solar energy is retained at heat in the atmosphere and on the surface of the Earth. Because glass also passes light and tends to absorb and reflect heat, this effect is compared to that of a greenhouse.


Ground-Reflected Radiation - the radiation from the sun which is reflected back into the atmosphere after striking the Earth.

Click Shining On (Figure 3) to see solar components


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