CS320 Digital Thermopile Pyranometer

The CS320 combines a blackbody thermopile detector with an acrylic diffuser. This design is a significant improvement when compared with the spectral response of silicon photocell pyranometers, while offering a comparable price. Thermopile pyranometers use a series of thermoelectric junctions (multiple junctions of two dissimilar metals following the thermocouple principle) to provide a signal of several µV/W/m2 proportional to the temperature difference between a black absorbing surface and a reference. The thermopile pyranometer’s black surface uniformly absorbs solar radiation across the solar spectrum. 

The 0.2 W heater keeps water (liquid and frozen) off the sensor to minimize errors caused by dew, frost, rain, and snow blocking the radiation path. Dew and rain runoff is faciliated by the dome-shaped sensor head (diffuser and body). This keeps the sensor clean and minimizes errors caused by dust blocking the radiation path. The sensor is housed in a rugged anodize aluminum body, and the electronics are fully potted. 

The CS320 pyranometer has sensor-specific calibration coefficients determined during the custom calibration process. Coefficients are programmed into the microcontrollers at the factory. The CS320 has an SDI-12 output (SDI-12 version 1.4), where short-wave radiation (W/m2) is returned in digital format. Measurement of the CS320 pyranometer requires a measurement device with SDI-12 functionality that includes the M or C command. 

Benefits and Features 

• • Thermopile sensor eliminates spectral errors associated with silicon-cell pyranometers 
  • Much lower price point than other thermopile sensors 
  • On-board sensor automatically detects if the CS320 is level for installation, diagnostics, and remote troubleshooting 
  • Designed for long-term stability and deployment 
  • Dome-shape sensor head allows dew and rain runoff 
  • Internal heater to reduce errors from dew, frost, rain, and snow 
  • SDI-12 digital output 
  • Detachable waterproof connector from sensor head for fast, easy servicing 
  • Calibration data stored on sensor