LPPYRA-Lite
- 4 -
V1.2
2
WORKING PRINCIPLE
LPPYRA-Lite pyranometer is based on a thermopile sensor. The thermopile sensitive
surface is coated with a black matt paint, which allows the pyranometer not to be se-
lective at different wavelengths.
Radiant energy is absorbed by the thermopile black surface, thus creating a difference
of temperature between the center of the thermopile (hot junction) and the pyranom-
eter body (cold junction). Thanks to the Seebeck effect, the difference of temperature
between hot and cold junction is converted into a Difference of Potential.
In order to grant the thermopile a proper thermal insulation from the wind and reduce
the sensitivity to thermal irradiance, LPPYRA-Lite is equipped with a glass dome. The
dome protects the thermopile from the dust, which might change spectral sensitivity if
it lies on the black surface,
To prevent internal condensation forming on the internal side of the dome under cer-
tain climatic conditions, silica gel tablets are inserted inside the pyranometer to ab-
sorb humidity.
1
2
3
4
Fig. 2.1: scheme of principle LPPYRA-Lite (version with mV output)
Thermopile
Connector pins
Housing