The meteo stations developed by Solar Millennium are an important component in the evaluation of potential locations for solar thermal power plants.
Our meteostations are using a rotating shadowband pyranometer (RSP) to very precisely determine direct normal irradiation (DNI). The first step is to measure the global irradiation, which includes both diffuse radiation and direct radiation. By turning the shadowband, a shadow is temporarily cast over the sensor, allowing the diffuse irradiation to be determined. Finally, the DNI can be determined from the difference between global irradiation and diffuse radiation (see graph, can be enlarged by clicking the magnifying glass).
Because the rotating shadowband pyranometer works without complicated sun tracking devices, it does not require a great deal of electricity or maintenance. This makes it ideal for self-sustaining use with power supplied from only a solar panel.