This product is no longer available and has been replaced by: SR30-D1. Some accessories, replacement parts, or services may still be available.
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Overview
The SR20-T2, manufactured by Hukseflux Thermal Sensors, is an ISO 9060:2018 spectrally flat Class A (secondary standard) pyranometer that measures solar short-wave radiation in a full hemisphere of the sky. It has a built-in case temperature sensor and embedded heater for removing dew and light rain. It connects directly to a Campbell Scientific data logger and is designed for applications that require high measurement accuracy in demanding applications such as scientific meteorological observation networks and utility scale solar-energy-power production sites.
Benefits and Features
- Low temperature dependence
- Embedded 1.5 W heater to reduce effects of dew deposition
- Embedded 10K temperature sensor
- Ultra robust connector, desiccant holder, and sun screen
- Temperature dependence characterized and supplied for each instrument
- Directional response tested on each instrument
Images
Detailed Description
The SR20-T2 pyranometer measures the hemispherical solar radiation received by a plane surface, in W/m2, from a 180° field of view. The SR20 can be deployed indoors with lamp-based solar simulators or more commonly outdoors under the sun. Its orientation depends on the application and may be installed horizontally, tilted for plane or array irradiance, positioned on a sun tracker with shadow-ring for diffuse measurements, or inverted for reflected radiation.
The SR20-T2’s low temperature dependence makes it an ideal candidate for use under very cold and very hot conditions. The temperature dependence of each instrument is tested and supplied as a second-degree polynomial. This information can be used for further reduction of temperature dependence during post-processing.
The SR20 is equipped with an internal temperature sensor. Campbell Scientific supplies the T2 version, which has a 10 kohm thermistor. The T1 version, in contrast, has a PT100 and is available upon request.
The embedded heater reduces measurement errors caused by early-morning dew deposition. Campbell Scientific recommends using the instrument in accordance with the recommended practices of ISO, WMO and ASTM.
The output of the SR20-T2 is analog. The SR20-D2-L model, in contrast, offers two other types of commonly used irradiance outputs: digital via Modbus RTU over 2-wire RS-485, and analog 4 to 20 mA output (current loop).
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Specifications
| Sensor | High-quality blackened thermopile protected by two glass domes |
| Measurement Description | Measures hemispherical solar radiation |
| ISO Classification | Spectrally flat Class A (secondary standard) pyranometer (ISO 9060:2018 ) |
| WMO Performance Level | High-quality pyranometer |
| Response Time | 3 s (95%) |
| Zero Offset A | 5 W/m2 (unventilated), 2.5 W/m2 (ventilated) (response to 200 W/m2 net thermal radiation) |
| Zero Offset B | ≤ -2 W/m2 (response to 5 K/h change in ambient temperature) |
| Non-Stability | ≤ -0.5% change per year |
| Non-Linearity | ≤ -0.2% (100 to 1000 W/m2) |
| Directional Response | < ±10 W/m2 |
| Spectral Selectivity | < ±3% (0.35 to 1.5 x 10-6 m) |
| Temperature Response | < ±1% (-10° to +40°C), < 0.4% (-30° to +50°C) with correction in data processing |
| Tilt Response | < ±0.2% (0 to 90° at 1000 W/m2) |
| Heater | 1.5 W (at 12 Vdc) |
| Steady-state Zero Offset | 0 to -8 W/m2 (caused by heating) |
| Calibration Uncertainty | < 1.2% (k=2) |
| Level Accuracy | < 0.1° (bubble entirely in ring) |
| Sensor Resistance Range | 100 to 200 ohm |
| Operating Temperature Range | -40° to +80°C |
| Field of View (FOV) | 180° |
| Measurement Range | 0 to 4000 W/m2 |
| Sensitivity | 7 to 25 x 10-6 V/(W/m2) |
| Spectral Range | 285 to 3000 x 10-9 m (20% transmission points) |
Compatibility
Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.
Data Loggers
| Compatible | Note | |
|---|---|---|
| CR1000 (retired) | ||
| CR1000X | ||
| CR300 | ||
| CR3000 (retired) | ||
| CR310 | ||
| CR6 | ||
| CR800 (retired) | ||
| CR850 (retired) |
Additional Compatibility Information
Power Considerations
The SR20-T2 heater is a 1.5 W heater at 12 Vdc. The SW12 power out port on the CR800/850, CR1000, and other data loggers can supply the needed 0.125 A for the heater, as that port can supply 0.9 A at 20°C. More typically, relays controlled by the data logger digital I/O ports are used to control the power supply.