6
SPECIFICATIONS
Calibration Traceability
Apogee Instruments SP series pyranometers are calibrated through side-by-side comparison to the mean of four Apogee
model SP-110 transfer standard pyranometers (shortwave radiation reference) under high intensity discharge metal halide
lamps. The transfer standard pyranometers are calibrated through side-by-side comparison to the mean of at least two ISO-
classified reference pyranometers under sunlight (clear sky conditions) in Logan, Utah. Each of four ISO-classified reference
pyranometers are recalibrated on an alternating year schedule (two instruments each year) at the National Renewable
Energy Laboratory (NREL) in Golden, Colorado. NREL reference standards are calibrated to the World Radiometric Reference
(WRR) in Davos, Switzerland.
SP-422
Resolution
0.1 W m
-2
Calibration Factor
Custom for each sensor and stored in firmware
Calibration Uncertainty
± 5 % (see Calibration Traceability below)
Measurement Repeatability
Less than 1 %
Long-term Drift
(Non-stability)
Less than 2 % per year
Non-linearity
Less than 1 % (up to 1750 W m
-2
)
Response Time
Software updates every second
Field of View
180º
Spectral Range
360 to 1120 nm (wavelengths where response is 10 % of maximum;
see Spectral Response below)
Directional (Cosine) Response
± 5 % at 75º zenith angle (see Cosine Response below)
Temperature Response
0.04 ± 0.04 % per C (see Temperature Response below)
Operating Environment
-40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths
of 30 m
Dimensions
24 mm diameter, 28 mm height
Mass
Sensor head weighs 90 g
USB Cable
4.6 m (15 ft)
Current Draw (when Logging)
2.1 mA
