The CS325DM-L, manufactured by Atonometrics as the RC18, is a silicon solar irradiation sensor commonly used as a “reference cell” in solar photovoltaic (PV) monitoring applications. This solar radiation sensor has a temperature operating range that allows it to work effectively in different environments. The sensor element was designed to correspond to PV modules, including spectral selectivity and incident angle modifier. The data signals are Modbus RTU RS-485 or analog.
Sensor | Silicon solar irradiation sensor |
Measurement Description | Solar irradiance measurements for outdoor monitoring of PV systems |
Irradiance Measurement Range | 0 to 1500 W/m2 |
Operating Temperature Range | -35° to +80°C |
Input Power | 8 to 28 Vdc (12 to 28 Vdc for 0 to 10 V analog output) |
Photovoltaic Cell | Crystalline Si, 20 mm x 20 mm, ~135 mA @ 1 sun |
Window | Low-iron solar glass, or CdTe-matching filter |
Cell Temperature Measurement | -40° to +100°C, Pt100 RTD |
Calibration Data | Internally calibrated; no calibration data to manage |
Enclosure Material | Powder-coated cast aluminum housing |
IP Rating | IP67 |
Cable Type | Shielded, weather-resistant, UV-rated, 24 AWG/0.2 mm2 |
Cable Connector | M12 circular connector, IP67 |
Response Time | 0.15 s |
Electronics Non-Linearity | ±0.03% of range |
Repeatability | ±0.02% of range |
Temperature Drift | ±0.4% at 1000 W/m2 (-35° to +80°C) |
Factory Calibration of Electronics | ±0.1% of reading ±0.2% of range |
Irradiance Calibration | ±1.8% (calibrated to NREL-traceable reference standard) |
Overall Measurement Uncertainty | ±2.0% of reading ±4 W/m2 |
Stability | 0.5% per year |
Mounting | 4 mounting holes with diameter 5.50 mm (0.217 in.) |
Dimensions | 115.1 x 65.0 x 30.0 mm (4.53 x 2.56 x 1.18 in.) |
Weight | 0.3 kg (0.6 lb) |
Digital |
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Communications Protocols | Modbus over RS-485, user-settable Modbus address |
Baud Rate | Up to 57.6 kbps |
Current Consumption | Typically 8 to 15 mA |
Analog |
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Analog Output Options |
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Analog Output Signals |
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Current Consumption |
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Output Impedance | 2 kohm (0 to 1.5 V or 0 to 10 V mode) |
Internal Voltage Drop | Allow 3.5 V minimum (4 to 20 mA mode) |
The CS325DM requires an RS-485 adapter if the data logger it is being used with does not support RS-485.
Two CR1000X data logger programs that read the CS325DM measurements. An example program is included for each output option (digital Modbus, analog). Program code for other data logger models will be similar.