Pyrheliometers
A Pyrheliometer is a device that measures the solar irradiance coming directly from the sun itself. This type of irradiance is also called ‘direct normal irradiance’ (DNI).
A pyrheliometer needs to be mounted on a solar tracker which is a device that points the instrument at the sun throughout the day. At the same time, to limit the measurement to the radiation coming only directly from the sun, it is necessary to limit the field of view of the instrument.
From outside the Earth’s atmosphere, the sun is seen as a disk with an angular distance of about 0.27°. At ground level, the sun looks a lot bigger. Its visual size depends on the atmosphere: the hazier the sky, the bigger the sun in the sky. As per WMO (World Meteorological Organisation) convention, all modern pyrheliometers use the same field of view, characterised by an opening half-angle of 2.5°. This means the measurement of direct solar radiation includes some amount of ‘circumsolar’ radiation – the diffuse radiation coming from the vicinity of the sun.
Traditionally pyrheliometers were mainly used for climatological research and weather monitoring purposes, however recent worldwide interest in solar energy has also led to an increased interest in pyrheliometers.
Solar radiation is one of the driving forces behind the earth’s weather patterns and thus an important factor in weather and climate studies. In such studies pyrheliometers are often combined with pyranometers to measure all components of the solar radiation; direct, global and diffuse.
Product Line
DR15 - A1
Manufacturer: Hukseflux
DR15 is a high-accuracy direct (normal incidence) solar radiation sensor, or pyrheliometers that complies with the Class B specifications of the ISO 9060:2018 standard. It is used in tracker-mounted operation, and offers analogue millivolt outputs. It has superior window heating that leads to high data availability.
Specifications:
- Measurand: direct solar radiation
- ISO classification: spectrally flat Class B
- Calibration uncertainty: < 1.2 % (k = 2)
- Heater: 1 W at 12 VDC
- Response time (95 %): 4 s
- Full field of view angle: 5°
- Slope angle: 1°
- Zero offset a (5K/hr): < ± 1 W/m²
- Spectral range:200 to 4000 x 10⁻⁹ m
- Rated operating temperature range: -40 to +80 °C
- Temperature response: < ± 1 % (-10 to +40 °C)
DR20 - A1
Manufacturer: Hukseflux
DR20-A1 is a high-accuracy direct (normal incidence) solar radiation sensor, or pyrheliometer. DR20 pyrheliometer complies with the Class A specifications of the ISO 9060 standard. It has a better temperature response than DR15-A1, which is a spectrally flat Class B pyrheliometer. These instruments are used in tracker-mounted operation, and offer analogue millivolt outputs.
Specifications:
- Measurand: direct solar radiation
- ISO classification: spectrally flat Class A
- Calibration uncertainty: < 1.2 % (k = 2)
- Heater: 1 W at 12 VDC
- Response time (95 %): 4 s
- Full field of view angle: 5°
- Slope angle: 1°
- Zero offset a (5K/hr): < ± 1 W/m²
- Spectral range: 200 to 4000 x 10⁻⁹ m
- Rated operating temperature range: -40 to +80 °C
- Temperature response: < ± 0.5 % (-10 to +40 °C)
DR30-D1
Manufacturer: Hukseflux
DR30 is a high-accuracy digital direct (normal incidence) solar radiation sensor. It complies with the Class A specifications of the ISO 9060 standard and the WMO Guide. This next level pyrheliometer has superior window heating that leads to high data availability, and an internal tilt sensor to check tracker performance..
Specifications:
- Measurand: direct solar radiation, sensor tilt angle
- ISO classification: spectrally flat Class A pyrheliometer
- Calibration uncertainty: < 1.2 % (k = 2)
- Tilt measurement uncertainty: ± 1 ° (0 to 180 °)
- Response time (95 %): 4 s
- Full field of view angle: 5°
- Slope angle: 1°
- Power consumption: standard operating mode – 2 W, low power operating mode – 0.1 W
- Zero offset a (5K/hr): < ± 1 W/m²
- Spectral range: 200 to 4000 x 10⁻⁹ m
- Rated operating temperature range: -40 to +80 °C
- Temperature response: < ± 0.4 % (-30 to +50 °C)