The principle of the pyranometer LP PYRA02 is based on a thermopile sensor. The surface sensibility of the thermopile is covered with an opaque black varnish, which allows the pyranometer not to be selective at different wavelengths. The spectral range
The pyranometer is determined by the transmission of the two model K5 glass cupolas.
The radiant energy is absorbed by the blackened surface of the thermopile, thus creating a difference in temperature between the center of the thermopile (hot seal) and the body of the pyranometer (cold seal). The temperature difference between the hot seal and the cold seal is transformed into a Difference of Potential, by the Seebeck effect.
The pyranometer LP PYRA 02 is provided with two concentric cupolas respectively 50 mm and 30 mm outside diameter to ensure thermal insulation the wind thermopile and to reduce the sensitivity to radiation
thermal. The cupolas protect the thermopile from the powder, which settles on the blackened part, could change the spectral sensitivity.
The pyranometer LP PYRA 02 must be installed in a place easily accessible for perform periodic cleaning of the outer dome and for maintenance. Of the more it is desirable to avoid constructions, trees or any other
other obstacle, go beyond the horizontal plane, where is the pyranometer. In the case where this would not be possible, we recommend choosing a position where the elements troublesome present on the course of the sun from dawn to sunset, are less than 5 °.
Important note: the presence of obstacles in the line of the horizon influence in a sensitive way the measurement of the direct radiation.
• The pyranometer should be placed away from any kind of obstruction, which can project the reflection of the sun (or its shadow) on the same pyranometer.
• When the pyranometer is used without the white screen, it must be positioned in such a way so that the electric cable goes out to the North Pole side, if it is used in the NORTHERN hemisphere, on the South Pole side, if it is used in the southern hemisphere, in accordance with ISO TR9901 and WMO recommendations. In all case it is better to follow this recommendation when using the screen too.