Comparison of Solar Radiation Sensors

 Various solar radiation sensors are available with the modular Capricorn FLX Weather Station and/or with the Weather MicroServer for all weather station models. Additionally, the Magellan MX and Pulsar Weather Stations offer all-in-one sensor modules with integrated solar radiation measurement.

ISO classifications “secondary standard,” “first class,” and “second class” correspond to the World Meteorological Organization categories “High quality,” “Good quality,” and “Moderate quality.”

Silicone-based Pyranometer This sensor is calibrated to measure the shortwave radiation reaching the Earth’s surface, measured in Watts per square meter. Silicon pyranometers are generally less expensive than thermopile sensors, yet often sufficient for many requirements.

Advantages:

– Low cost – Sensor head is potted solid to prevent internal condensation in humid environments – Self-cleaning dome-shaped head prevents water accumulation Applications: General purpose solar monitoring.

Specifications:

ISO classification: None Cosine Response: 45° zenith angle ± 1%, 75° zenith angle ± 5% Absolute Accuracy: ± 5% Uniformity: ± 3% Repeatability: ± 1% Output Responsivity: 0.200 mV per W/m² Linear Range: 0 - 350 mV (0 - 1,750 W/m²) Sensitivity: Custom calibrated to exactly 0.5 W/m² per mV Input Power: 5 volts DC Operating Environment: - 40 to 55 °C; 0 to 100% relative humidity. Designed for continuous outdoor use Materials: Anodized aluminum with acrylic lens Dimensions: 2.4 cm diameter, 2.75 cm high

Second Class Pyranometer

Thermopile-based Pyranometer: Second Class This thermopile sensor meets ISO 9060 Second Class requirements. It measures solar radiation received by a plane surface, in W/m², from a 180° field of view angle.

Advantages:

Easy mounting and installation Applications: Ideal for general solar radiation measurements in meteorological networks and photovoltaic monitoring.

Specifications:

ISO classification: ISO 9060 Second Class Spectral range: 280 to 3000 nm Calibration Uncertainty: < 1.8% (k=2) Operating Temperature Range: -40 to +80°C Output: 0 to 1VDC

First Class Pyranometer

Thermopile-based Pyranometer: First Class This thermopile sensor meets ISO 9060:1990 First Class requirements and features a sixty-four thermocouple junction (series connected) sensing element. The sensing element is coated with a highly stable carbon based non-organic coating, which delivers excellent spectral absorption and long term stability characteristics. It has improved performance due to the increased thermal mass and the double glass dome construction.

Advantages:

Accurate solar radiation measurements Durable Applications: Operations that require accurate data for photovoltaic power.

Specifications:

ISO classification: ISO 9060:1990 First Class Spectral range (20% point): 280 to 3000 nm Spectral range (50% point): 285 to 2800 nm Response time (63%): <1.5 s Response time (95%): <12 s Zero offset A: <10 W/m² Zero offset B: <4 W/m² Directional response (up to 80° with 1000 W/m² beam): <15 W/m² Temperature dependence of sensitivity (-40°C to +70°C): <3% Output: 0 to 1VDC

Secondary Standard Pyranometer

Thermopile-based Pyranometer: Secondary Standard This thermopile sensor meets ISO 9060:1990 Secondary Standard requirements (highest possible ISO pyranometer performance category). It extends this quality to applications where maintenance is difficult and/or forms a major part of the cost of ownership.

The sensor uses a temperature compensated detector and has better linearity and long-term stability, lower thermal offset and faster response than a first class pyranometer.

The faster response time meets the requirements for solar energy monitoring.

Advantages:

Accurate solar radiation measurements Internal drying cartridge that will last for at least 10 years if the housing is not opened Applications: Operations that require accurate data for photovoltaic power.

Specifications:

ISO classification: ISO 9060 Secondary Standard Spectral range (50% point): 285 to 2800 nm Response time (63%): <0.7 s Response time (95%): <2 s Zero offset A: <7 W/m² Zero offset B: <2 W/m² Directional response (up to 80° with 1000 W/m² beam): <10 W/m² Temperature dependence of sensitivity (-40°C to +70°C): <1% Output: 0 to 1VDC

Magellan MX 501 with solar radiation sensor

Magellan MX Weather Station model 501 incorporates a silicon photodiode radiation sensor in the all-in-one sensor configuration including wind speed/direction, air pressure, temperature, relative humidity, compass and GPS.

Wavelength Sensitivity: 300 to 3000 nm Output Range: 0 to 1600 W/m² Resolution: 1 W/m² DIN Standard: IS0 9060 Second Class Sampling Rate: 1 Hz Units: W/m²

Pulsar Weather Station model 501 integrates a second class thermopile solar radiation sensor in an all-in-one sensor housing with ultrasonic wind speed and direction, temperature, relative humidity, air pressure, and electronic compass.

Model 501 ISO classification: Second Class Response time (95%): <18s Non-stability (change/year): <1% Non-linearity (0 to 1,000 W/m²): <1% Directional error (at 80° with 1,000 W/m²): <20 W/m² Temperature dependence of sensitivity: ±5% (-10 to +40°C) Tilt error at 1,000 W/m²: <1% Spectral range (50% points): 300 to 2800 nm Maximum irradiance: 1400 W/m²

Pulsar Weather Station models 800, 700, and 502 incorporate a silicon photodiode radiation sensor in the all-in-one multi-parameter sensor configuration. Model 502 offers ultrasonic wind speed and direction, temperature, relative humidity, air pressure, electronic compass. Model 700 and 800 add Doppler Radar precipitation measurement. Model 800 also adds lightning detection.

Models 800, 700, 502 Response time (95%): <1 s Unit: W/m² Accuracy: 5% Spectral range (50%points): 300 to 1100 nm Measuring range: 1400 W/m²