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This integrated solar irradiance is called solar irradiation, solar radiation, solar exposure, solar insolation, or insolation. Irradiance may be measured in space or at the Earth's surface after atmospheric absorption and scattering. Irradiance in space is a function of distance from the Sun, the solar cycle, and cross-cycle changes. [2]
The latter standard represents the spectral distribution of global irradiance incident on a 37° tilted surface facing the sun at an air mass of 1.5. The integrated irradiance amounts to 1000 W/m 2. This standard spectrum is mandated by IEC to evaluate the rating of photovoltaic (PV) solar cells in the absence of optical concentration.
The nonlinear I-V curve characteristic of a given cell in specific temperature and insolation conditions can be functionally characterized by a fill factor (FF). Fill factor is defined as the ratio of the maximum power from the cell to the product of open circuit voltage V oc and short-circuit current I sc .
The global irradiance on a horizontal surface on Earth consists of the direct irradiance E e,dir and diffuse irradiance E e,diff. On a tilted plane, there is another irradiance component, E e,refl, which is the component that is reflected from the ground. The average ground reflection is about 20% of the global irradiance.
Radiant intensity is used to characterize the emission of radiation by an antenna: [2], = (), where E e is the irradiance of the antenna;; r is the distance from the antenna.; Unlike power density, radiant intensity does not depend on distance: because radiant intensity is defined as the power through a solid angle, the decreasing power density over distance due to the inverse-square law is ...
Solar irradiance spectrum above atmosphere and at surface. The overall intensity of solar radiation is like that of a black body radiator of the same size at about 5,800 K. [1] As it passes through the atmosphere, sunlight is attenuated by scattering and absorption; the more atmosphere through which it passes, the greater the attenuation.
Its distance to the Sun varies annually between 147.1·10 6 km at perihelion and 152.1·10 6 km at aphelion. In addition, several long term (tens to hundreds of millennia) cycles of subtle variation in the Earth's orbit (Milankovich cycles) affect the solar irradiance and insolation (but not the solar constant).
In such applications, radiative transfer codes are often called radiation parameterization. In these applications, the radiative transfer codes are used in forward sense, i.e. on the basis of known properties of the atmosphere, one calculates heating rates, radiative fluxes, and radiances. There are efforts for intercomparison of radiation codes.