SR05-D1A3-PV manual v1801 63/83
high or low Check the location of the pyranometer; are there any obstructions that could
explain the measurement result.
Check the orientation / levelling of the pyranometer.
Check the cable condition looking for cable breaks. Check the condition of the
connectors (on chassis as well as the cable).
The sensor
signal shows
unexpected
variations
Check the presence of strong sources of electromagnetic radiation (radar, radio).
Check the condition and connection of the shield.
Check the condition of the sensor cable.
Check if the cable is not moving during the measurement.
Check the condition of the connectors (on chassis as well as the cable)
8.3 Calibration and checks in the field
Recalibration of field pyranometers is typically done by comparison in the field to a
reference pyranometer. The applicable standard is ISO 9847 “International Standard-
Solar Energy- calibration of field pyranometers by comparison to a reference
pyranometer”. At Hukseflux an indoor calibration according to the same standard is used.
Hukseflux recommendation for re-calibration:
if possible, perform calibration indoor by comparison to an identical reference instrument,
under normal incidence conditions.
The recommended calibration interval of pyranometers is 2 years. The registers
containing the applied sensitivity and the calibration history of SR05 are accessible for
users. This allows the user to choose his own local calibration service. The same feature
may be used for remotely controlled re-calibration of pyranometers in the field. Ask
Hukseflux for information on ISO and ASTM standardised procedures for field calibration.
Request “power user” status and a password at the factory permitting to write to
registers holding the sensitivity and the calibration history data via the Sensor Manager.
In case of field comparison; ISO recommends field calibration to a higher class
pyranometer. Hukseflux suggests also allowing use of sensors of the same model and
class, because intercomparisons of similar instruments have the advantage that they
suffer from the same offsets. It is therefore just as good to compare to pyranometers of
the same brand and type as to compare to an instrument of a higher class. ISO
recommends to perform field calibration during several days; 2 to 3 days under cloudless
conditions, 10 days under cloudy conditions. In general this is not achievable. In order to
shorten the calibration process Hukseflux suggests to allow calibration at normal
incidence, using hourly totals near solar noon.
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