Class A pyranometer SR20

analogISO 9060

Overview
SR20 is a solar radiation sensor of the highest category in the ISO 9060 classification system: spectrally
flat Class A. SR20 pyranometer should be used where the highest measurement accuracy is required. It
is often used with data loggers that can directly accept its analog voltage output.

Key features

• Class A performance: Fully compliant with ISO 9060:2018 spectrally flat Class A classification, WMO high quality pyranometer level, and IEC 61724-1:2021 Class A PV monitoring system requirements.
• Unsurpassed measurement accuracy: Initial calibration uncertainty is reduced to less than 1.2 % (k = 2) with an ultra-low “zero offset a” of < 5 W/m² unventilated (2.5 W/m² ventilated with VU01).
• Individual testing and reporting: Test certificates for temperature response and directional response (reported to 95°) of every individual instrument are included in delivery as required by ISO 9060:2018.
• Low temperature response: Features temperature response < ± 1 % (-10 to +40 °C), supplied with an individual second-degree polynomial to reach < ± 0.4 % (-30 to +50 °C) with correction in data processing.
• Integrated dew and frost mitigation: Incorporates an on-board heater (1.5 W at 12 VDC) to reduce measurement errors caused by early-morning dew and frost deposition.
• State-of-the-art construction: Built with a black-coated thermopile sensor, two glass domes, an anodised aluminium body, a sealed sun screen, and an ultra-robust IP67 connector with interchangeable cables.
• User-serviceable desiccant cartridge: Features a rugged aluminium desiccant holder with visible humidity indicator, wrench-operated O-ring seal, and a service interval of > 2 years.
• Lowest total cost of ownership: Supported by a worldwide calibration organisation to simplify recalibration every 2 years and reduce ownership costs.

Applications

• PV system performance monitoring (compliant with IEC 61724-1 Class A).
• Scientific meteorological observations and high-accuracy weather networks.
• Demanding solar measurement applications under very cold and very hot conditions.
• Horizontal and Plane of Array (POA) solar monitoring installations.

Specifications

• Measurand: Hemispherical solar radiation [W/m²]
• ISO 9060:2018 classification: Spectrally flat Class A pyranometer
• WMO performance level: High quality pyranometer
• IEC 61724-1 compliance: Meets Class A PV monitoring system requirements for all locations and climatic conditions
• Calibration uncertainty: < 1.2 % (k = 2)
• Calibration traceability: To WRR (World Radiometric Reference)
• Spectral range: 285 to 3000 x 10⁻⁹ m
• Sensitivity (nominal): 15 x 10⁻⁶ V/(W/m²)
• Analogue output: Millivolt / analog voltage output
• Zero offset a: < 5 W/m² unventilated; 2.5 W/m² ventilated (with VU01)
• Rated operating temperature range: -40 to +80 °C
• Temperature response: < ± 1 % (-10 to +40 °C); < ± 0.4 % (-30 to +50 °C) with correction in data processing
• Temperature sensor: Pt100 or 10 kΩ thermistor
• Heater: 1.5 W at 12 VDC (activate when the sun is below the horizon)
• Standard cable length: 5 m
• Connector rating: IP67 grade

Optional accessories and mounting options

• Longer cable (available in multiples of 5 metres)
• VU01 ventilation unit
• PMF01 and PMF02 pyranometer mounting fixtures (for horizontal and Plane of Array installations)