Apogee SP series silicon-cell pyranometers

The Apogee SP series are silicon-cell pyranometers. They measure global shortwave radiation on a flat surface, which does not have to be horizontal, and output an analog voltage proportional to that radiation. Each sensor has a cast acrylic diffuser, a photodiode and signal processing circuitry in an anodized aluminum housing. The sensor is potted solid with no internal air space, so it can be used outdoors continuously. The family includes the SP-100 and SP-200 series, for example the SP-230 all-season model. The datasheet states accuracy of about plus or minus 5 percent under clear sky and a four year warranty. The photodiode responds only to about 350 to 1100 nm. Expect spectral errors when conditions differ from the clear-sky calibration, for example under cloudy skies or at other zenith angles and air masses. Because of this limited spectral sensitivity, these sensors do not meet the spectral specification needed for WMO or ISO certification, even though their other specifications compare favorably. Directional error is about plus or minus 2 percent at a 45 degree solar zenith angle and plus or minus 5 percent at 75 degrees. Sensors are calibrated under metal halide lamps against SP-110 transfer standards. The calibration chain runs through ISO-classified reference pyranometers recalibrated at NREL, which in turn trace to the World Radiometric Reference. The sensors work with most dataloggers. In monitoring installs the SP-110 can be wired as a plane-of-array pyranometer input.

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• sentence 8: support check: partial - Compatibility with most dataloggers is stated, but the SP-110 being wired as a plane-of-array input is only hinted by a bare 'POA' label fragment, not stated. -->