SR20-T2-L
SR20-T2-L
RetiredISO Class A Pyranometer with 10K Thermistor
No longer available to order
This product is retained for service, documentation, and compatibility information.
Replaced by
- SR30
Class A Pyranometer with RS-485 Modbus Communications with Integrated Heating and Ventilation
- Model:
- SR20-T2-L
- Item Number:
- 32308
- Warranty:
- 5 years
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.
Key Advantages
Ideal for PV system performance monitoring
Technical 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).
Benefits
- 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
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)
Common Accessories
(4)CM255
Solar Adjustable-Angle Mounting Stand
One stand is needed per pyranometer. The CM255 is one of two options. The CM255 is used to mount the SR20-T2-L at an angle.
OrderableCM256
Adjustable Plane and Angle Solar Mounting Stand
The CM256 adjustable-angle, adjustable-plane mounting stand further simplifies the accurate and precise mounting of a pyranometer, ventilation unit, shadowband radiometer, or reference cell. Several pyranometer mounting stands have been combined and simplified to make ordering easier and usability friendlier. The CM256 is a combination of the CM255LS pyranometer mount, CM245 reference cell and shadowband mount, 31394 VU01 mount, and 31153 CVF4 mount. In addition, several new sensors are now fully supported such as the SPN1, MS-80(M), SR30, SR05, and IMT reference cell CM325.
OrderableCM261
Single-Axis Tracker Mounting Stand
One CM261 is needed per VU01-L. The CM261 single-axis tracker pyranometer mount with adjustable plane simplifies the mounting of any pyranometer, ventilation unit, reference cell, or SPN1 to octagonal, round, and square single-axis torque tubes. The CM261 is a combination and simplification of the CM260 and CM265 to make ordering easier and usability friendlier. The bracket includes provisions for mounting the sensors and ventilation units at different heights, allowing the sensing element to be mounted at the same height as the solar modules.
OrderableCMB200
Crossarm Brace Kit
The CMB200 Crossarm Brace Kit is designed to provide additional stability when using a crossarm mounted on Campbell Scientific tripods and towers. This kit provides support for crossarms with heavier or sensitive sensor loads, as well as added stability in higher winds. Each kit includes one brace arm and three sets of mounting brackets.
Orderable
Replacement Parts
(4)SR20-T2CBL
Replacement Cable for the SR20-T2
This replacement cable includes a mating connector for the SR20-T2-L and uses raw cable part number 8865. This cable is a 24 AWG, one twisted-pair with seven conductors in a shield with a drain and Santoprene jacket.
Orderable32309
Desiccant Drying Packets for SR20-T2-L (quantity of 5)
The 32309 is a five-pack of desiccant drying packets for the SR20-T2-L. The humidity indicator for the pyranometer should be inspected periodically. The color blue indicates dryness. A pink color, however, indicates it is humid and the desiccant packet should be replaced.
Orderable34512
M6 x 25 mm Stainless-Steel Screw with 1 mm Thread Pitch and Hex Socket Head
The 34512 is used to secure the SR20-T2-L to the CM255LS Adjustable-Angle Solar Sensor Mounting Stand.
Orderable31373
M6 18-8 Stainless-Steel External Tooth Lock Washer
The 31373 is commonly used with the 34512 screw to secure the SR20-T2-L to the CM255LS Adjustable-Angle Solar Sensor Mounting Stand.
Orderable
Services
(2)33475
Pyranometer ISO 17025 Accredited Calibration to ASTM G167 and ISO 9846 with Data
The 33475 calibration service is performed using an intermittent shade method with a World Radiometric Reference (WRR) traceable AHF cavity radiometer. The 33475 calibration is ISO 17025 accredited to the following standards: ASTM G167 and ISO 9846.
Orderable33476
Solar Sensor ISO 17025 Accredited Calibration to ASTM E824 with Data
The 33476 calibration service is performed using a reference group of pyranometers traceable to World Radiometric Reference (WRR). This calibration is ISO 17025 accredited to ASTM E824 standard.
Orderable
Compatibility
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.
