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6 Maintenance and trouble shooting
6.1 Recommended maintenance and quality assurance
16131.5 can measure reliably at a low level of maintenance in most locations. Usually unreliable
measurements will be detected as unreasonably large or small measured values. As a general rule
this means that regular visual inspection combined with a critical review of the measured data,
preferably checking against other measurements, is the preferred way to obtain a reliable
measurement.
Table 6.1.1
Recommended maintenance of 16131.5. If possible the data analysis and cleaning (1 and
2) should be done on a daily basis.
MINIMUM RECOMMENDED PYRANOMETER MAINTENANCE
INTERVAL
SUBJECT
ACTION
1
1 week
data analysis
compare measured data to maximum possible / maximum expected
irradiance and to other measurements nearby (redundant instruments).
Also historical seasonal records can be used as a source for expected
values. Analyse night time signals. These signals may be negative
(down to - 5 W/m
2
on clear windless nights), due to zero offset a. In
case of use with PV systems, compare daytime measurements to PV
system output. Look for any patterns and events that deviate from what
is normal or expected.
2
2 weeks
cleaning
use a soft cloth to clean the dome of the instrument, persistent stains
can be treated with soapy water or alcohol
3
6 months
inspection
inspect cable quality, inspect connectors, inspect mounting position,
inspect cable, clean instrument, clean cable, inspect levelling, change
instrument tilt angle in case this is out of specification, inspect mounting
connection, inspect interior of dome for condensation
4
2 years
recalibration
recalibration by side-by-side comparison to a higher standard
instrument in the field according to ISO 9847
5
lifetime
assessment
judge if the instrument should be reliable for another 2 years, or if it
should be replaced
6
> 5 years
desiccant
replacement
desiccant replacement by manufacturer.
7
parts
replacement
if applicable / necessary, replace the parts that are most exposed to
ageing and weathering; cable, connector, sun screen, ventilator.
NOTE: use manufacturer approved parts only.
ventilator replacement by manufacturer.
