Hukseflux SR05 series - Appendix On ISO and WMO Classification Tables

SR05-D1A3-PV manual v1801 72/83
9.7 Appendix on ISO and WMO classification tables
Table 9.7.1 Classification table for pyranometers per ISO 9060 and WMO.
NOTE: WMO specification of spectral selectivity is different from that of ISO. Hukseflux
conforms to the ISO limits. WMO also specifies expected accuracies. ISO finds this not to
be a part of the classification system because it also involves calibration. Please note that
WMO achievable accuracies are for clear days at mid latitudes and that the uncertainty
estimate does not include uncertainty due to calibration*.
ISO CLASSIFICATION** TABLE
ISO CLASS
SECONDARY
STANDARD
FIRST CLASS
SECOND
CLASS
Specification limit
Response time (95 %) 15 s 30 s 60 s
Zero offset a (response to 200 W/m
2
net
thermal radiation)
+ 7 W/m
2
+ 15 W/m
2
+ 30 W/m
2
Zero offset b (response to 5 K/h in ambient
temperature)
± 2 W/m
2
± 4 W/m
2
± 8 W/m
2
Non-stability (change per year) ± 0.8 % ± 1.5 % ± 3 %
Non-linearity (100 to 1000 W/m
2
)
± 0.5 %
± 1 %
± 3 %
Directional response
± 10 W/m
2
± 20 W/m
2
± 30 W/m
2
Spectral selectivity (350 to 1 500 x 10
-9
m)
(WMO 300 to 3 000 x 10
-9
m)
± 3 % ± 5 % ± 10 %
Temperature response (interval of 50 K)** 2 % 4 % 8 %
Tilt response
(0 to 90 ° at 1000 W/m
2
)
± 0.5 %
± 2 %
± 5 %
ADDITIONAL WMO SPECIFICATIONS
WMO CLASS HIGH QUALITY GOOD QUALITY MODERATE
QUALITY
WMO: achievable accuracy for daily sums*
2 %
5 %
10 %
WMO: achievable accuracy for hourly sums* 3 % 8 % 20 %
WMO: achievable accuracy for minute sums* not specified not specified not specified
WMO: resolution
(smallest detectable change)
1 W/m
2
5 W/m
2
10 W/m
2
CONFORMITY TESTING***
ISO 9060 individual
instrument only:
all specs must
comply
group
compliance
group
compliance
* WMO 7.2.1: The estimated uncertainties are based on the following assumptions: (a)
instruments are well-maintained, correctly aligned and clean; (b) 1 min and 1 h figures
are for clear-sky irradiances at solar noon; (c) daily exposure values are for clear days at
mid-latitudes. WMO 7.3.2.5: Table 7.5 lists the expected maximum deviation from the
true value, excluding calibration errors.
** At Hukseflux the expression ± 1 % is used instead of a range of 2 %.
*** an instrument is subject to conformity testing of its specifications. Depending on the
classification, conformity compliance can be proven either by group- or individual
compliance. A specification is fulfilled if the mean value of the respective test result does
not exceed the corresponding limiting value of the specification for the specific category
of instrument.