Solar Irradiance

The results that are presented in the following were calculated with METSUN, a program developed by METCON. It includes internationally approved methods for the calculation of the solar irradiance taking into account the actual position of the sun, cloud cover, orientation of the receiving surface, reflection and shading.

Example 1: Optimisation of the orientation of receiving surfaces
An accurate estimation of the usable energy amount is a pre-requisite for a reliable planning and profitability analysis of photovoltaic and solar thermal systems. Simulation of the irradiance taking into account the general conditions at the designated location allows an optimisation of the orientation of receiving surfaces and therewith results in a maximum energy gain.

A receiving surface that is not shaded is optimally adjusted if it is orientated in a southward direction and inclined by about 35°.
Global radiation [W/m2] against orientation of the receiving surface.
If, for example, part of the sky south-eastern of the receiving surface is masked by a building, the surface should be orientated more to the west and be more gently inclined.

Example 2: Irradiance at the regional scale
Plant growth - agricultural production, for example - depends on the solar irradiance. Therefore, agronomical and ecological calculations require highly resolved information about the irradiance at the regional scale in which local exposition and shading by the topography are taken into account.

Mean global radiation in the surroundings of the Saidenbach reservoir in Saxony/Germany, May 2002.


Example 3: Irradiation of buildings
Irriadiation in residential areas is an important criterion for the quality of life. With information about the exposition of buildings to the solar radiation lighting conditions in internal spaces can be studied, usage of energy be optimised and the risk of stress and destruction of materials by irradiance and thermal fluctuations be assessed.

Example for the mean annual irradiance in an urban area.
Irradiance on the facade that lies northerly vis-à-vis of the high-rise building (W/m2). One sees the shading by the high-rise building and how the brightness increases towards the crossing.